茨城大学重点研究「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」

茨城大学工学部附属
防災セキュリティ技術教育研究センター
２０１４年度報告書

茨城大学重点研究「知的で持続可能な社会基盤および防災セキュリティ技術創出事業」
平成 26 年度報告書刊行にあたって
プロジェクト代表

呉 智深

本研究課題は，平成 23 年 4 月に課題募集プロポーザルとその審査により茨城大学重点研究課
題として認定され，工学部，教育学部および茨城大学センター教員から構成される異分野研究者の集う場として活動が始まりました．本年度は活動 4 年目を迎えることとなりました．
この報告書では，学術誌論文をはじめとする研究成果に加えて，参加メンバーの学術企画の開催や参加，受賞例についても整理しましたが，「防災セキュリティ技術」という学際領域に類するテーマが示すように，昨年度に引き続き，多種多様な研究活動とその成果を収めてきたことが分かりました．
この重点研究課題で芽生えた研究成果は，平成 24 年 1 月に開所式が行われた工学部付属教育研究センター「防災セキュリティ教育研究センター」に引き継がれ，平成 25 年 4 月には，日本・中国・韓国各国の関係分野の先進的研究者が集う国際シンポジウムを土木学会茨城会と共催，
平成 25 年 12 月には日本リモートセンシング学会国土防災リモートセンシング研究会主催 WS「次の大災害時に備えて、衛星画像の可能性」を後援(工学部)し，センターメンバーが主催側に参画しました．「教育と研究」双方の分野を対象として着実に成果を重ねつつあり，今後大型連携プ
ロジェクトの獲得を含め、ますますの発展に向けて鋭意努力してゆく所存であります．
末筆とはなりますが，茨城大学重点研究課題として採択頂き，茨城大学を代表する研究課題の一つとして諸方面の応援と援助を頂きました茨城大学に心から感謝申し上げますとともに，必ずしも十分でなかった研究交流にも関わらず，本誌に示す多大なる研究成果を上げている参加メンバーに心から敬意と謝意を表します．
今後の研究活動への努力をお約束し，関連する皆様に感謝を申し上げますとともに，ここに平成 26 年度の研究成果を報告させて頂きます．

平成 27 年 3 月吉日
プロジェクト代表

呉 智深

－目次－
Ⅰ. 研究報告
1. A. M. A. Ibrahim, Zhishen Wu, M. F. M. Fahmy, and Doaa Kamal,
Experimental Study on the Structural Performance of Concrete
Bridge Columns Reinforced by Hybrid Steel and FRP
Reinforcements (submitted)－1－
2. Yusuke Takamaru, Sachin Rai and Hiromasa Habuchi,
Theoretical Analysis of New PN Code on Optical WirelessCode-Shift-Keying,
IEICE Transaction on Fundamentals, Vol.E97-A, No.12,
pp.2572-2578, (2014-12)－57－

Ⅱ.プロジェクト業績
1. 活動内容－64－
2. 実績一覧－67－

Ⅰ.研究報告（H26 年度参加教員発表の代表的な学術論文集）

Manuscript
Click here to download Manuscript: manuscript.docx
茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Experimental Study on the Structural Performance of Concrete Bridge Columns

1

Reinforced by Hybrid Steel and FRP Reinforcements

2

Arafa M. A. Ibrahim1, Zhishen Wu 2*, Mohamed F. M. Fahmy3, and Doaa Kamal4

3

Abstract: This paper presents the seismic performance of concrete bridge columns reinforced4with hybrid steel and fiber reinforced polymer (FRP) reinforcements. A mechanical model

5

describing the required damage-control performance of the proposed FRP-steel reinforced

6

concrete (FSRC) structure is first discussed. A bond-based parametric experimental study was

7conducted on five FSRC bridge columns (using basalt FRP (BFRP) bars) and two reference

8steel-reinforced concrete bridge (SRC) columns to investigate the fundamental characteristics of9

the proposed reinforcement. All columns were tested under the combined effect of constant axial

10

load and reversed cyclic loading. The investigated bond parameters included the texture of the11

FRP bars (smooth and ribbed); diameter of the FRP bars; location of the FRP bars with respect to12

the steel bars; and application of external FRP confinement. Different ductility and post-

13

earthquake recoverability indices were applied to explore the effect of each design parameter on

14

the performance of the proposed FSRC system. The experimental results show that RC bridge

15

columns with both steel and FRP bars as longitudinal reinforcements could realize the existence

16

of a stable hardening behavior (i.e., post-yield stiffness) as well as a reasonable displacement

17

ductility of up to 10 before encountering strength degradation. Moreover, the number of FRP

18

bars added for column longitudinal reinforcement did not have a substantial impact on the19column elastic stiffness. The bond condition of the FRP bars to the surrounding concrete could20

be adopted as a design parameter because it had pronounced effects on the column failure mode,

21

post-yield stiffness, residual displacement, and ductility. In addition, wrapping the plastic hinge

22

region with an FRP jacket had a substantial effect on column ductility and energy dissipation.

23

-1-

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

CE Database subject headings: FRP bar; Basalt; Bridge; Column; Ductility; Recoverability;

24

Damage control; Bond; Post-yield stiffness.

25
26

1

Ph.D. Candidate, Dept. of Urban and Civil Engineering, Ibaraki University, 4-12-1

27

Nakanarusawa-cho, Hitachi 316-8511, Japan, E-mail: arafa_dem@yahoo.co.uk

28

2*

29

Corresponding author, Professor, Dept. of Urban and Civil Engineering, Ibaraki University, 4-12-1 Nakanarusawa-cho, Hitachi 316-8511, Japan, E-mail: zswu@mx.ibaraki.ac.jp30

3

Assistant Professor, Dept. of Civil Engineering, Assiut University, Assiut, 71516, Egypt, E-

31

mail: mfmf1976@yahoo.com

32

4

MSc Candidate, Dept. of Urban and Civil Engineering, Ibaraki University, 4-12-1

33

Nakanarusawa-cho, Hitachi 316-8511, Japan, E-mail: 14nm826a@vc.ibaraki.ac.jp

34
35
36

-2-

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Introduction

37

In recent seismic design philosophies of important bridges located in active seismic regions,38

quick post-earthquake recoverability of structural function has been considered in addition to39

ductility demand and energy dissipation (Kawashima 2000; Kawashima et al. 1998). Studies

40

conducted by Kawashima et al. 1998; Christopoulos et al. 2003; Pettinga et al. 2007 showed that41

the post-yield stiffness ratio (i.e., the ratio of the post-yield stiffness to the initial elastic stiffness)42

of a bridge column is the main parameter controlling column residual displacement; for instance,

43

at a given lateral displacement, a higher post-yield stiffness results in a smaller residual

44

displacement. Priestley et al. 1996; Christopoulos et al. 2003; Wu et al. 2009 emphasized that the45

uncontrollable damage of conventional steel-reinforced concrete (RC) structures is due to the46

elasto-plastic characteristics of ordinary steel bars. Other studies (e.g., Dhakal and Maekawa

472002) reported that the main reasons for the non-ductile behavior of RC structures are the48

spalling of the cover concrete and buckling of the longitudinal reinforcement as a result of

49

insufficient transverse reinforcement in the plastic hinge regions.

50

The damage level and residual displacement of bridge columns after an earthquake could be

51

reduced by incorporating an unbonded-prestressed strand at the center of the column cross52

section (Ikeda et al. 2002; Zatar and Mutsuyoshi 2002; Sakai et al. 2006). Wu et al. 200953

proposed a steel- fiber reinforced polymer (FRP) composite bar (SFCB) as another technique54

that can be applied in the field of civil engineering to combine the advantageous mechanical and55

physical properties of both steel and FRP composites, the high elastic modulus and good56

ductility of a common steel bar and the good anti-corrosion ability and elasticity of FRP

57

composites. This bar consisted of an inner steel core and outer longitudinal continuous fiber

58

layer. Reinforcing RC bridge columns with steel-fiber composite bars enabled the mitigation of

59

-3-

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

their residual displacement and the control of their post-yield stiffness (Fahmy et al. 2010).

60

Moreover, analytical and experimental studies on this reinforcing material showed that the post-

61

yield stiffness depends on the properties of the fibers used, whereby columns reinforced with62

steel-basalt fiber composite bars exhibited a larger drift capacity before the rupture of the basalt

63

fibers than those reinforced with steel-carbon fiber composite bars (Fahmy et al. 2010). Although64

scale model columns reinforced with this type of composite bars exhibit a favorable seismic

65

performance with damage-controllable states after yielding, the production of comparable

66

composite bars for practical application with larger inner steel cores may require an excessive

67

amount of outer longitudinal fiber material, which would complicate the production process; thus,

68

using many composite bars with a smaller inner steel core would be necessary. In addition, the69bond performance between composite bars and concrete must be further improved .

70

The objective of this study is to investigate the application of both steel and FRP bars as a

71

longitudinal reinforcement in earthquake-resisting structural elements. To achieve this objective,72

a design guideline in light of both current code provisions and a proposed damage control

73

performance was followed to define the design details of steel-FRP reinforced columns. The

74

bond between the FRP bar and surrounding concrete, as a key parameter that could affect column

75

performance, was examined by using FRP bars with different textures and diameters. In addition,76

the effect of replacing some of the transverse steel reinforcement with external FRP confinement

77

was examined. The efficiency of the proposed reinforcement design and the role of different

78

parameters were investigated in a detailed experimental program considering the effect of both79

constant axial load and horizontal cyclic loading tests on RC bridge square columns.

80

FRP-Steel RC Structure

81

-4-

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Because post-yield stiffness is the main factor that influences the strength demand, seismic82

stability, and residual displacement of RC structures (Iemura et al 2006; Christopoulos and83

Pampanin 2004), it is important to develop a tool to control the structural post-yield stiffness.

84

General guidelines and design equations for longitudinal and transverse steel reinforcement of85

concrete bridges to achieve high ductility and dissipate sufficient energy before failure have been

86

well defined in current design codes. The specifications of the current design codes can produce

87

RC structures that can withstand severe earthquakes; however, the elasto-plastic characteristics

88of steel reinforcement would cause difficulty in quickly recovering structural functions after an

89earthquake. In this study, FRP composites are proposed to be added to the longitudinal90

reinforcement in RC bridge columns because merging the elastic characteristics of FRP

91

composites with conventional steel reinforcement could provide the structure with the desired

92

post-yield stiffness.

93

In this regard, two conventional steel-reinforced concrete (SRC) bridge structures, SRC1 and94

SRC2, were first tested. SRC1 was designed to withstand moderate earthquakes, whereas SRC295

was designed to resist a massive earthquake. Compared with SRC1, an additional increase in the96

concrete dimensions and/or steel reinforcement is necessary in SRC2. However, with the elastic

97

characteristics of FRP composites, it would be possible to increase the lateral resistance of SRC1

98

to the required level without an increase in the column steel reinforcement or concrete99

dimensions by adding longitudinal and transverse FRP composites to the original SCR1. Fig. 1

100compares the schematic reinforcement model for the proposed FSRC structure and that of the101

conventional SRC structures. The proposed FSRC structure is the conventional steel RC

102

structure with the addition of longitudinal FRP reinforcement (FRP bars) and transverse FRP

103reinforcement (FRP sheets applied as a continuous jacket or separated strips).

104

-5-

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

A detailed mechanical model of the proposed FSRC structure, Fig. 2, is addressed here in

105
106

comparison with the two SRC structures. This model is a modified form of the proposed damage

107

control model for existing RC structures retrofitted with FRP composites (Fahmy et al. 2009),

108

where further developments meeting the requirements of modern codes for new structures are

109

considered. As shown in Fig. 2, the idealized lateral load-deformation response of the proposed

110system (FSRC) goes along the path represented by O-C-Y-M-S-F, whereas the performances of111

the two conventionally reinforced concrete bridges (SRC1 and SRC2) are represented by O-C1-

112

Y1-M1-F1 and O-C2-Y2-M2-F2, respectively. The proposed system using FRP-steel reinforcement

113

is designed for the life safety performance objective to withstand moderate earthquakes with its

114

elastic performance and exhibit the demand strength of a strong earthquake to ensure the115

existence of a stable post-yield stiffness. Prior to the yielding of the steel reinforcement,

116

structures SRC1 and FSRC share similar initial elastic stiffnesses, K1, whereas SRC2 exhibits a117

higher elastic stiffness. The higher yield stiffness of the structure would lead to a shorter

118

vibration period and increase the earthquake forces received (Saiidi et al. 2009). Beyond the119yielding of the SRC structures, the deformations of both SRC1 and SRC2 increase dramatically,120

whereas the increase in the lateral load is insignificant. In other words, SRC demonstrates a121small post-yield stiffness along lines Y1-M1 and Y2-M2 (see Fig. 2). In contrast, the proposed

122

FRP-steel system ensures the gradual increase in lateral resistance up to the demand strength of a123

strong earthquake along line Y-M such that the system could realize the existence of a124

considerable post-yield stiffness, K2. Beyond the yielding point, SRC systems experience

125

extensive straining of the steel reinforcement to achieve the required ductility; thus, after peak126

loading (and a stability zone in some cases), the earthquake-resisting structural elements are

127

subject to significant damage, e.g., major spalling of the concrete cover and buckling of the main

128

-6-

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

steel reinforcement. The failure point of the SRC system corresponds to a 20% reduction in the

129

maximum achieved lateral strength, points F1 and F2 for SRC1 and SRC2, respectively.

130

Compared with the SRC system, the proposed system is characterized by a clear stability zone of131

the peak strength (zero stiffness (K3)) along line M-S, whereby the structure demonstrates the132

desirable ductile performance before the strength degradation. Furthermore, the FRP elements

133

used are employed as a fuse-resisting element to be replaced after a strong earthquake to restore

134

the original structural function. Therefore, the failure point of this system is defined when the135contribution of the FRP elements to the lateral resistance is completely lost along path S-F136(negative stiffness (K4)).

137

The performance of the proposed FRP-steel system can be divided into four distinctive zones

138

according to the earthquake level and damage level. Zone 1, from points O to Y: through this139zone, the structure may be attacked by small-to-moderate earthquakes without experiencing any

140

pronounced damage, and after an earthquake, the original function of the structure can be

141

restored without any repair or replacement of elements. Zone 2, from points Y to M: through this142zone, under a strong earthquake, the damage can be effectively controlled by the secondary143

stiffness (Fahmy et al. 2009). The original function of the structure can be quickly recovered

144

through minor repair work on damaged structural elements while the structure is open to all

145

traffic. Zone 3, from points M to S, is where a desired ductility after hardening under a large

146

earthquake should be achieved. In this zone, damage to the substructural elements, such as major

147

spalling of the concrete cover, may occur, but the proposed system can be maintained without

148

collapse. The original function of the structure may also be recovered by repairing damaged parts

149of the concrete and replacing FRP reinforcement elements. In this zone, the structure can be used

150

by emergency vehicles for life-saving purposes. Ultimately, through Zone 4 from points S to F,

151

-7-

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

only the FRP reinforcement (earthquake-resistant elements) of the substructural elements

152(columns) would be damaged until its contribution to the lateral strength fully vanishes. In this153

stage, limited access to service shall be permitted until structural function is completely

154

recovered via the replacement of damaged elements.

155

To this end, the proposed structural system using steel and FRP reinforcement has several

156

advantages with respect to the counterpart steel-reinforced structural system. The initial stiffness157

is smaller than that of steel-reinforced bridges (SRC2), and therefore, a considerable reduction in158

the seismic force input into the structure can be achieved. Second, the existence of the stable159

post-yield stiffness controls the lateral deformation after yielding and reduces the residual

160

displacement (permanent deformation) after an earthquake.

161

Experimental Program162

An experimental investigation on concrete bridge columns reinforced with both FRP and steel

163

reinforcement was conducted. One column (CS-2%) was designed as a reference for a RC bridge

164

column that can safely resist moderate earthquakes, while another column (CS-4%) was

165

considered to resist nearly twice the lateral force of the first column. A complete design was also

166

provided for a concrete column with the same concrete parameters and steel reinforcement of

167

CS-2% in addition to FRP reinforcement. The following section describes the design parameters

168

of both the steel and FRP reinforcements.

169

Design of the Proposed Steel and FRP Columns

170

Design of Steel RC Columns

171

A cantilever bridge column with an overall height of 1.0 m, a cross section of 200x200 mm, and172

a distance from the column base to the point of the lateral load application of 850 mm, yielding173

an aspect ratio of 4.25, was proposed for this experimental study. A target compressive strength

174

-8-

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター(′

of 30 MPa was applied to all examined columns. The yield strength (fy) and ultimate

175

strength of the 13-mm-diameter deformed steel bars used as longitudinal reinforcements were176

375 and 560 MPa, respectively, and the corresponding values for the 6-mm-diameter steel

177

transverse reinforcements were 400 and 625 MPa, respectively (see Table 1). Before applying178

the proposed cyclic loading that will be explained later, an axial load of approximately 40 kN,

179

inducing an axial compression stress of 1 MPa (Zatar and Mutsuyoshi 2002), was applied on all

180

column specimens. Using the aforementioned data, details of the conventional reinforced steel

181

columns were defined as follows:

182

Longitudinal Steel Reinforcement

183

AASHTO 2012 specifies that the area of the longitudinal reinforcement (Al) of columns located184

in a high-seismic-hazard area is to be no less than 0.01 or more than 0.04 times the gross cross-185

sectional area Ag (i.e., 0.01 ≤ ρl ≤ 0.04, where ρl is the steel reinforcement ratio and equal to Al

186/ Ag). In this study, the first steel-reinforced column (CS-2%) used six longitudinal steel bars of

187

13-mm-diameter (i.e., ρl=2%), whereas the second column (CS-4%) was reinforced with twelve

188

steel bars of 13-mm-diameter (i.e., ρl=ρl max=4%, where ρl max is the maximum steel

189

reinforcement ratio). The theoretical strengths of these two samples were 36.0 and 67 kN,

190

respectively, and both values were defined using the AASHTO 2012 rectangular stress block for

191

concrete in compression, which has a mean stress of 0.85f΄c and an ultimate concrete

192

compression strain of 0.003, and a steel stress of fy for the longitudinal steel bars.

193

Transverse Reinforcement

194

To ensure a ductile reinforced concrete column, it is critical to provide the plastic hinging

195

regions with transverse reinforcement to confine the concrete core, prevent early buckling of the196

longitudinal reinforcement, and ensure a dominant flexural failure mode. To achieve the

197

-9-

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

specified demand displacement ductility, Wehbe et al. 1999 proposed Eq. 1 to define the198

required transverse reinforcement as follows:

199

′

√ ′

[

(

)

(

)]

(1)

200

is the201

dimension of the concrete core of the section measured perpendicular to the direction of the hoop

202

bars to the outside of the perimeter hoop, Sh is the center-to-center vertical spacing of the hoops

203

not exceeding 4.0 in, Ag is the gross area of the column cross section, fcn=27.6 MPa, fsn=414 MPa,

204′

where Ash is the area of transverse reinforcement in each of the transverse directions,

fyl is the yield stress of longitudinal steel reinforcement,′is the concrete compressive strength,

205

P is the axial load, and μ is the demand displacement ductility factor.

206

Using Eq. (1) and assuming a displacement ductility demand before failure of μ <10 (Wehbe et207

al. 1999), the transverse reinforcement required was 6-mm-diameter stirrups with a spacing of 50

208

mm. With reference to the design provisions of AASHTO 2012, it would be reasonable to use 6-

209

mm-diameter stirrups with a spacing of 25-mm- or 8-mm-diameter stirrups with a spacing of 50

210

mm. The transverse reinforcement defined by AASHTO 2012 is independent of the column

211

reinforcement ratio. From a practical perspective, because the amount of transverse

212

reinforcement defined by Eq. (1) could achieve this level of ductility, replacement of some of the213

inner transverse steel reinforcement (based on AASHTO 2012) with external FRP jacket would214

increase the concrete cover’s compressive strength. Therefore, for all columns, the transverse

215

steel reinforcement was determined based on Eq. 1, which is nearly 60% of the stirrups required216

by AASHTO 2012. Moreover, an external BFRP jacket was provided in some experimental

217

cases to develop the same shear strength with the reduced amount of transverse steel

218

reinforcement. By using an FRP sheet with the mechanical properties shown in Table 1, it was

219- 10 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

found that wrapping the plastic hinge region of the columns with a 0.666-mm-thick FRP jacket

220

would compensate for the decrease in shear strength and provide a good confinement to the221

concrete cover.

222

Design of FRP-Steel RC Columns

223

The FRP-steel RC (CSF) column had the same steel reinforcement as column CS-2% (6 steel

224

longitudinal bars of 13-mm diameter and steel stirrups of 6-mm diameter spaced at 50 mm),

225

which would result in a flexural strength of 36.0 kN, as stated previously. Therefore, additional

226

FRP bars were added to reach a strength comparable to that of column CS-4% (67.0 kN). Among227

all available types of FRP materials, basalt fiber (BFRP) shows advantageous mechanical and228

chemical characteristics and a high performance-to-cost ratio. For instance, BFRP has a higher

229

strength and modulus, a similar cost, and a greater chemical stability than E-glass FRP; a wider

230

range of working temperatures and lower cost than carbon FRP (CFRP); and a five-fold higher

231

strength and approximately one-third the density of commonly used low-carbon steel bars (Wu et232

al. 2010; Sim et al. 2005; Palmieri et al. 2009). Due to the above advantages, BFRP bars were233

used to investigate the proposed FRP-steel RC design. Using BFRP bars with a tensile strength234

and elastic modulus of 1,120 MPa and 48 GPa, respectively, as shown in Table 1, four BFRP

235

bars of 10-mm diameter or six BFRP bars of 8-mm diameter would increase the column strength236

to the desired value. To prevent problems of plastic hinge relocation, anchorage failure, or other237

failure modes, the BFRP bars in this study were extended to a height of 700 mm from the238

column base and embedded in the column footing to a depth of 300 mm.

239

Test Specimens and Experimental Parameters

240

Seven different column units were prepared to investigate the efficiency of the proposed241

reinforcements. All column units had a deep concrete base of 1.0 x 0.5 x 0.5 m (length x width x

242- 11 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

depth), which simulated a rigid foundation for the tested column. Due to its roles in acting as a243

foundation and resisting the action induced by applied loads, the concrete base was provided

244

with heavy reinforcement to ensure its elastic performance during the tests of all columns.

245

Similar to the steel RC column, its cross-section was 200 x 200 mm, and its height was 1,000

246

mm. The distance from the column base to the point of the application of the lateral load was 850

247

mm, with an aspect ratio of 4.25. To avoid any unexpected local failure at the loading region, the248transverse steel reinforcements were spaced at 30 mm in the highest 300 mm portion of the249

column units. All columns were attached to a strong steel floor using four vertical high-strength250

steel rods. The geometry and instrumentation of a typical column unit are shown in Fig. 3.

251

The test specimens were designed such that the effect of a series of parameters on the seismic252

response of the proposed concrete bridge columns could be investigated. These parameters

253

include the type of reinforcement (ordinary steel bars only or both steel and FRP bars); diameter254of the FRP bars (10 mm or 8 mm); texture of the FRP bars (smooth or rough texture); location of255

the FRP bars in the tension and compression cross-section sides (internally in the same fibers as

256

the longitudinal steel bars, or externally in the concrete covers); and use of FRP jacketing (with257

or without). A detailed description of the test specimens follows and is supported by Figs. 3, 4

258

and 5 and Table 2:259

Specimen CS-2% (Fig. 4.a) served as a reference specimen for the steel RC columns. In this260

column, the longitudinal steel reinforcement consisted of six 13-mm-diameter bars (i.e.,261

ρl=0.02), and the transverse reinforcement consisted of 6-mm-diameter internal closed

262

stirrups spaced every 50 mm;

263

Specimen CS-2%-J (Fig. 4.b) was reinforced with the same steel reinforcement as specimen264

CS-2%. In addition, BFRP jacketing was provided to the plastic hinge region of this column,265- 12 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター











where a jacket of 0.333-mm thickness was applied to the lowest 300 mm of the column (i.e.,266

Lj1=300 mm) and then another jacket of 0.333-mm thickness was added to only the lowest

267

200 mm of the column portion (i.e., Lj2=200 mm);

268

In addition to the steel reinforcement details of column CS-2%, specimen CSF-2.8%-IS-D10

269(Fig. 4.c) was reinforced with two 10-mm-diameter BFRP bars placed on each of two

270

opposite sides of the column (those with the highest tension/compression) at the same place271

as the longitudinal steel bars. The surface texture of the BFRP bars contained small272

prefabricated indentations (factory product), as shown in Fig. 5.b. By adding the FRP bars to273

the steel bars, the resulted reinforcement ratio was nearly 2.8% (i.e., ρl=0.028);

274

Specimen CSF-2.8%-IS-D10-J (Fig. 4.d) was similar to specimen CSF-2.8%-IS-D10 but

275

wrapped at the plastic hinge region with the same BFRP jacketing as in column CS-2%-J;

276

Specimen CSF-2.8%-IR-D10-J (Fig. 4.d) was the same as specimen CSF-2.8%-IS-D10-J, but

277

the surface texture of the BFRP bars was spirally roughened with BFRP strips in two

278

perpendicular directions, as shown in Fig. 5.c;279

Specimen CSF-2.8%-ES-D10-J (Fig. 4.e) was the same as specimen CSF-2.8%-IS-D10-J,

280

but the BFRP bars were placed outside of the steel stirrups, i.e., in the concrete cover. In

281

addition, BFRP jacketing was provided to the plastic hinge region of this column, where a282

jacket of 0.333-mm thickness was applied first to the lowest 600 mm of the column portion

283(i.e., Lj1=600 mm) and then another jacket of 0.333-mm thickness was added to only the284

lowest 200 mm of the column portion (i.e., Lj2=200 mm); and285

Specimen CSF-2.8%-ES-D8-J (Fig. 4.f) was reinforced with both steel and FRP

286

reinforcement and wrapped with the BFRP jacketing as in specimen CSF-2.8%-ES-D10-J,

287

but the FRP reinforcement consisted of three 8-mm-diameter BFRP bars placed external to288- 13 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

the steel stirrups on each of two opposite sides of the column (those with the highest

289

tension/compression) in the concrete cover. The surface texture of the BFRP bars contained

290

small indentations, as shown in Fig. 5.a. The total reinforcement ratio in this column was291

approximately 2.8% (i.e., ρl=0.028).

292

Loading and Instrumentation

293

All columns were subjected to a constant axial load of 40 kN and several excursions of lateral294

cyclic loading applied at 850 mm above the column base using a dynamic actuator with a295

capacity of 700 kN. The reversed cyclic loading sequence was determined based on the column

296

displacement at the yielding load (Δy), which was numerically defined for the reference column

297

and kept the same for all specimens. The lateral loading sequence started with two cycles of298

0.5Δy followed by two cycles of Δy and then three cycles each of 2Δy, 3Δy, 4Δy, 6Δy, 8Δy, and299

10Δy until failure. A linear variable differential transformer (LVDT) was used during testing to300

record the horizontal displacement of the tested columns. The axial strain histories for both the301

steel and FRP reinforcements were recorded during the test by using a set of 5-mm-long strain

302

gauges, arranged as shown in Fig. 6. Although efforts were made to keep the axial load constant303

during the experimental tests, laterally displacing the columns resulted in some variations in the304

axial load, particularly at high levels of lateral displacement. The actual applied axial load was in305

the range of 40 to 100 kN during the tests. All installed instrumentation are shown in Fig. 3.

306

Experimental Results and Discussion

307

General Observations and Hysteretic Curves

308

In this section, the results of each column specimen are individually discussed with reference to309

its hysteretic response (V-δ curve) and failure mode. Fig. 7 shows the lateral load versus the310

column drift ratio for all tested columns, and Fig. 8 shows the final failure mode of these311- 14 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

columns. The deformation capacity of the columns is expressed as the member lateral drift,

312

which is defined as the ratio of the lateral displacement at the point of the load application of313

each column to the effective height of the column (850 mm). The longitudinal strains of the FRP

314

bars are also examined, where the lateral load-FRP bar strain hysteresis loops were recorded by

315

the FRP bar’s strain gauge in each column, as shown in Fig. 9. Table 3 summarizes the316characteristic values and experimental findings in both the positive and negative loading317

directions together with the observed failure mode of each specimen, and Table 4 contains the318

average characteristic values of both directions. The terms Vcr and Vy represent the cracking load319

and steel yielding load, respectively, and the terms δcr and δy represent the corresponding lateral320

displacements. The cracking load and corresponding displacement were approximately defined321

from the first turning points of the load-displacement curves when the plastic hinge zone was

322

covered with an FRP jacket. The yielding loads and displacements were obtained from the323

results of the strain gauges attached to the longitudinal steel bars. The term VP represents the324

peak load, and it is characterized by two displacement values δP1 and δP2, where δP1 corresponds

325

to the peak load and δP2 corresponds to the end of the plateau zone, if any. The terms Vu and δu326

represent the ultimate load and its corresponding displacement, respectively, and they were327

defined for SRC specimens at the drift level at which the load capacity decreased to 80% of the328

peak load. For the other columns (FSRC columns), the ultimate loads and displacements were329

defined at the degradation of the peak load to the peak load of the SRC column, column CS-2%.

330

Values of the displacement ductility factor, µ, at different characteristic points were331

superimposed on the hysteretic responses, as shown in Figs. 7 and 9, where µ=δ/δy and δ=lateral332

displacement at the load application point. Moreover, a complete description of the failures noted333- 15 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

during the loading of all columns was included in the hysteretic curves using marked footnotes.

334

The following sections provide a detailed discussion of the behavior of all tested columns.

335

Columns Reinforced with Steel Bars (SRC Columns)

336

For the control specimen CS-2%, flexural cracks first occurred near the column base in the first337

loading cycle at a drift level of approximately 0.1%, corresponding to a lateral load of 9.2 kN.

338

While displacing the specimen in both loading directions, new horizontal and slightly inclined339

cracks formed and propagated with further loading and distributed in the lowest 300 mm of the340

column in both loading directions. The first yielding of the steel bars was observed at a drift level341

of 0.65%, corresponding to a lateral load of 26.0 kN, as shown in Fig. 7.a. Afterward, a stable342

hardening cyclic response appeared and continued up to a drift level of 3.5% (µ =5.3),

343

corresponding to an average peak load of 37.5 kN in both the push and pull directions. Following

344

this drift level, a peak-loading horizontal plateau was formed with the appearance of significant

345

wide cracks in the plastic hinge regions up to a drift level of 5.9% (µ=8.8). A bulking of the346

concrete covers accompanied with a smooth degradation of the cyclic response after this level347

took place up to a drift level of 7% (µ=10.3). Beyond this level, a complete spalling and crushing348

of the concrete cover within a height of approximately 200 mm above the column footing

349

occurred. After the spalling of the concrete cover, a serious buckling of the longitudinal350

reinforcement, Fig. 8.a, was observed, causing a sudden drop in the lateral load and terminating351

the test.

352

For specimen CS-2%-J, the behavior was significantly affected by wrapping the plastic hinge353

region with the FRP jacket (see Figs. 7.b and 8.b). The use of the BFRP jacket prevented the354

crack propagation from being observed, but the load-displacement curve demonstrated that the355

first turning point, indicating the first cracking, was at a drift level and corresponding lateral load356

- 16 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

nearly the same as those of the control specimen. The first yielding of the steel reinforcement357

took place at a drift level of 0.64%, corresponding to a lateral load of 27.2 kN (i.e., Vy=1.05 Vyc,

358

where Vyc is the yielding load of column CS-2%). After the yielding of the steel bars, the column359

was able to continue carrying a load in a stable manner up to a drift level of 5.9% (µ=8.9),360

corresponding to a peak lateral load of 43.4 kN (i.e., VP=1.15VPC, where VPC is the average peak361

load of column CS-2%). Beyond this drift, a gradual bulging of the FRP jacket accompanied by a362

smooth gradual loss of strength took place up to an average lateral drift of 9.4% (µ=14.3),

363

corresponding to a lateral load of 40.8 kN. Upon increasing the lateral displacement beyond this364

drift level, the bulging of the FRP jacket was accompanied by a local buckling of the steel bars

365

within a height of approximately 100 mm above the column footing, followed by the rupture of366

some steel bars, as shown in Fig. 8.b.

367

Columns Reinforced with Hybrid Steel and FRP Reinforcements (FSRC Columns)

368

Prior the yielding of the steel bars, the observed behavior of all FSRC columns was slightly

369

affected by the contribution of the FRP reinforcement. This could be due to the small

370

contribution of the FRP bars to both the column strength and deformation, and this was identified

371

from the average longitudinal strain records of BFRP bars located at both loading sides, which372

ranged from 8.5% to 11% of the uniaxial rupture strain of the BFRP bars (i.e., εfy=0.085 to 0.11373

εr, where εfy is the average strain recorded in the FRP bars at the yielding of the steel bars and εr374

is the rupture strain of the BFRP bar). This small contribution is due to the small elastic stiffness375

ratio between FRP and steel (i.e., Af Ef/AS ES=0.095, where A and E are the gross cross-sectional376

area and elastic modulus, respectively, and subscripts S and f denote the steel and FRP bars,

377

respectively). Beyond the yielding of the steel bars, the contribution of the FRP reinforcement378

became significant and controllable, where a hardening zone with a clear positive post-yield379- 17 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

stiffness was realized. Compared to the control specimen, all specimens reinforced with both

380

steel and FRP bars achieved considerably higher lateral strength (i.e., 30-85% higher than that of381

column CS-2%). In contrast to the control column, the failure modes of all FRP-reinforced

382

specimens were never attributed to the buckling of the internal reinforcement, as a significant

383

portion of the total force in the compression zone was carried by the FRP bars. However,384

buckling of the longitudinal internal bars occurred abruptly after bond or rupture failure of the385

FRP bars. The main observations of the behavior of such columns are described in detail in the386

following paragraphs.

387

Columns Reinforced with 10-mm-diameter BFRP Bars

388

For column CSF-2.8%-IS-D10, small cracks were first observed during the first loading cycle

389

near the column base. With further loadings, these cracks increased and distributed within the390

lowest 300 mm of the column height. The applied strain gauges recorded a first yielding strain of391

the steel bars at a drift level of 0.74%, corresponding to a lateral load of 27.6 kN. As shown in

392

Fig. 7.c, beyond the yielding of the steel bars, the column continued carrying loads with a stable393

post-yield stiffness up to a lateral drift of 3.5% (µ=4.2), corresponding to a peak load of 48 kN

394(VP=1.28VPC) in one loading direction. In the other loading direction, a peak lateral load of 50.5

395

kN (VP=1.35VPC) was reached at a drift of 4.7% (µ=5.6). During this hardening zone, a396

considerable propagation of cracks appeared and further widened. After reaching the peak load,397

the concrete cover at the column footing interface and above it started to bulk out, causing a

398

plateau at the peak load level. Along this plateau, concrete crushing and spalling became399

significant, particularly within the first 200 mm near the column footing. A “popping” sound was400

heard during the loading of the column to a lateral drift of 7% (µ=8.5), at which the measured

401

strain εf of the BFRP bars was 0.47εr, indicating the first local bond failure between the FRP bars402

- 18 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

and surrounding concrete at the column-footing interface. At this drift level, a 20% decrease in403

the load capacity occurred, confirming the effect of slippage between the FRP bars and404

surrounding concrete. An additional degradation in the column strength of 5% up to the405completion of the first loading cycle to a lateral drift of 8.2% (µ=9.9) was also observed. A

406“popping” sound was heard again when loading to the second and third cycles of the same lateral407

drift, together with separation of the concrete from the footing, which clearly indicated another408

local bond failure of the FRP bars. The strain of the FRP bars at this drift level was409

approximately 54% of the rupture uniaxial strain (i.e., εfy=0.54 εr), as shown in Fig. 9.c.

410

However, as a result of the applied cyclic loading, the partial rupture of the BFRP bars was

411

observed within the first 100 mm above the column base. Consequently, another 40% decrease in412

the carried load occurred. Hence, all of the stresses in the longitudinal direction were carried by413

the steel bars, resulting in a sudden local buckling of some of them and subsequently their414

rupture. Fig. 8.c shows the state of column CSF-2.8%-IS-D10 just before the rupture of the steel

415

bars.

416

Figs. 7.d, 8.d, and 9.d show that the observed trim of the behavior of specimen CSF-2.8%-IS-

417

D10-J was similar to that of specimen CSF-2.8%-IS-D10 up to a high loading level. The first418

yielding of the steel bars was recorded at a lateral load of 28.1 kN, corresponding to a drift of

419

0.6%. The column achieved a peak load of 56.75 kN (VP=1.51VPC) at a drift level of 5.9%420(µ=6.8) in one loading direction and a peak load of 59 kN (VP=1.57VPC) at a drift of 4.7%421(µ=5.4) in the opposite loading direction. Beyond the peak load, a stability in this load was422

observed up to a drift level of 7% (µ=8.1), at which point the first bond failure of the FRP bars

423

occurred, causing an average decrease of 15% in the lateral load. Beyond this deformation level,424

the column maintained the remaining lateral load up to a drift level of 8.2% (µ=9.5), at which425- 19 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

point a complete debonding of the FRP bars occurred, accompanied by another drop in the lateral426

load by approximately 20%. As a consequence, the steel bars became vulnerable to high stresses,

427

resulting in local buckling and subsequent rupture of some of them, causing a termination of the428

column test, as shown in Fig. 8.d. The maximum achieved strain in the FRP bars before the429bonding failure was approximately 56% of the rupture strain, as shown in Fig. 9.d.

430

The response of column CSF-2.8%-ES-D10-J shows the effect of placing FRP bars out of the431

transverse reinforcement in the concrete cover (see Fig. 7.f). Compared to CSF-2.8%-IS-D10-J

432

that was internally reinforced with FRP bars, a slight increase in the carried lateral load could be

433

achieved. This increase was attributed to the increase in the effective depth of the FRP bars (i.e.,434

the distance from the fibers of the maximum compression strain to the center of the FRP bars

435

located on the tensile side). As shown in Fig. 7.f and summarized in Table 3, the first yielding of436

steel bars was recorded at a drift level of 0.67%, corresponding to a lateral load of 33.2 kN.

437

Beyond the yielding of the steel bars, the column showed a gradual increase in the carried lateral438

load in both loading directions up to drift levels of +4.7% (µ=6.7) and -5.9% (µ=8.6),

439

corresponding to lateral loads of +63 kN (VP=1.68VPC) and -60 kN (VP=1.6VPC), respectively.

440

Afterward, local bond failure of the FRP bars occurred as the bond stress between the FRP bars

441

and surrounding concrete reached the bond strength. Two successive drops of the lateral load442

were observed in both loading directions, where the lateral load in the two loading directions at a443

drift level of 9.4% (µ=10.3) reached values of +37.5 and -38.3 kN. Before the debonding of the444

FRP bars, the recorded strain was approximately 61% of the rupture strain, as shown in Fig. 9.f.

445

The presence of the FRP bars outside the closed stirrups resulted in a pronounced rupture of the446

external fibers of the BFRP bars, particularly after the bulging of the BFRP jacket, as shown in

447

Fig. 8.f.

448- 20 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Specimen CSF-2.8%-IR-D10 examined the effect of roughening the texture of the BFRP bars on449

the bond between the FRP bars and concrete. Fig. 7.e and Table 3 show that the first yielding of450

steel bars was at a lateral drift of 0.69%, corresponding to a lateral load of 28.1 kN. Beyond the451yielding of the steel bars, a hardening zone of this column was realized in a manner quite similar452

to that in column CSF-2.8%-IS-D10, with smooth FRP bars, up to a drift level of 3.5%. After

453

this lateral drift ratio, the hysteretic loops showed a continuous increase in column strength but

454with a smaller positive stiffness in both loading directions up to the completion of the first455

loading cycle of the lateral drift of 8.2% (µ=11.3), corresponding to lateral loads in the positive456

and negative directions of 60 kN (VP=1.6VPC) and 69 kN (VP=1.84VPC), respectively. Displacing457

the column in the two directions with the additional two loading cycles to the same lateral drift

458

resulted in an approximately 25% loss in the achieved peak lateral strength. This drop was459

mainly due to a complete rupture of the FRP bars at 50 mm above the column base, as shown in

460

Fig. 8.e. At this loading stage, a loud sound was heard, and a bulge formed in the BFRP jacket.

461

During the loading process, the strain gauges located at the section of maximum moment failed

462

early, and only the strain gauge located at 150 mm height continued until the rupture of the463

BFRP bars. The maximum attained axial strain of the FRP bars recorded by this strain gauge was464

approximately 71% of the uniaxial rupture strain, as shown in Fig. 9.e. Following the rupture of465

the FRP bars, a sudden increase in the stresses were experienced by the steel bars, causing some466

of them to rupture.

467

Columns Reinforced with 8-mm-diameter BFRP Bars

468

The observed behavior of specimen CSF-2.8%-ES-D8-J was highly similar to that of the column

469

reinforced with rough BFRP bars; this could be attributed to good bond conditions between the470

FRP bars and surrounding concrete in both cases. As shown in Fig. 7.g and Table 3, the first471- 21 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

yielding of the steel bars was recorded at a drift level of 0.65%, corresponding to a lateral load of472

31.9 kN. Beyond the yielding of the steel bars, this column achieved the largest lateral resistance473

among all tested columns, where at a drift of 7% (µ=10.3), the maximum attained lateral474

strengths in the positive and negative directions were 68 kN (VP=1.81VPC) and 71 kN

475(VP=1.89VPC), respectively. At this drift level, a loud sound was heard, indicating the probability476

of rupture of one or more FRP bars, followed by an approximately 15% decrease in the peak load.

477

The column was then able to maintain its achieved strength up to a lateral drift of 8.2%, at which478

point a second loud sound was heard, indicating the probability of rupture of the additional FRP

479

bars, accompanied with another 25% decrease in the lateral load, after the completion of the480

second loading cycle at this drift level. Unfortunately, the results of the third loading cycle at this481

drift level were lost during the transfer of the data from the logger. The continued displacement482

of the column led to a rupture of some steel bars. The results of this column indicated that the483

FRP bars fulfilled nearly 94% of its rupture strain before failure, as shown in Fig. 9.g. Moreover,484

after removing the FRP jacket at the lowest part of the column, the decreases in the lateral load

485

were confirmed to be due to the rupture of the FRP bars, as shown in Fig. 8.g.

486

Envelope Responses

487

The average skeleton curves of push and pull loading directions of all tested specimens are488

presented in this section. To investigate the effect of each tested parameter individually, the489

skeleton curves of all specimens are shown in five separate figures, where the effect of each490

parameter can be investigated in one figure, as shown in Fig. 10. Referring to sec. 2, the491

effectiveness of the proposed column reinforcement should be evaluated in light of the targeted492

mechanical load-displacement model. To this end, the evaluation process is presented in this493

section in terms of initial stiffness, post-yield stiffness, and ductility measurements, as shown in494- 22 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Table 5. To draw firm conclusions, the response of the steel RC column (CS-4%), discussed

495

earlier, was numerically simulated using the OpenSees software (Mazzoni et al.). The

496

experimentally applied cyclic loading regime was adopted in the numerical simulation to predict497

the behavior of column CS-2% for comparison with the experimental results (see Fig. 10.a) and498

then to predict the performance of column CS-4%. Only the envelope response of the hysteretic

499

curve is presented here for comparison with the FSRC columns.

500

Initial Stiffness

501

The initial stiffness or elastic stiffness (K1) is an important seismic performance measure (index)

502

that can be evaluated as K1=Vy/δy. In comparison cases, higher values of this index would lead to503

a shorter vibration period of the structure and would generally increase the earthquake forces504

received (Saiidi et al. 2009). K1 was determined for all tested specimens to investigate the effect505

of adding FRP reinforcement to the steel reinforcement, as shown in Table 5.

506

As shown in Fig. 10 and summarized in Table 5, adding FRP composites to the steel

507

reinforcement resulted in an insignificant change in the initial stiffness values. Although508

wrapping the plastic hinge region with an FRP jacket resulted in a significant enhancement in the509

column confinement, the increase in the initial stiffness was extremely small; K1 of column CS-

510

2%-J=1.06 K1 of column CS-2%, and K1 of column CSF-2.8%-IS-D10-J=1.07 K1 of column

511

CSF-2.8%-IS-D10. Placing additional FRP bars for further transverse reinforcement had no clear

512

effect on the initial stiffness compared with the reference column CS-2%, whereas adding FRP

513

bars of 8- or 10-mm diameter in the concrete cover (outside the transverse reinforcement)

514

resulted in an approximately 20% increase in the initial stiffness. Moreover, the bond condition

515

between the FRP bars and concrete showed no considerable effect on the initial stiffness; K1 of516

column CSF-2.8%-IR-D10-J

517

K1 of column CSF-2.8%-IS-D10-J, and K1 of column CSF-2.8%-- 23 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

ES-D8-J

K1 of column CSF-2.8%-ES-D10-J. In contrast, Fig. 10.b and Table 5 show that the518

initial elastic stiffness of the numerically investigated column CS-4% was over twice that of the519

control specimen. That is, increasing the column strength to withstand a strong earthquake using

520

additional steel reinforcement would greatly affect the elastic stiffness and in turn its vibration

521

period, whereas adding FRP bars to an RC structure would be a reasonable solution to avoid any

522

increase in the imposed seismic force on the structure.

523

Post-Yield Stiffness524

In previous studies on damage-controlled structures, e.g., Kawashima et al. 1998; Christopoulos

525

et al. 2003; Pettinga et al. 2007, the residual deformations are dependent on the post-yield526

stiffness ratio. For instance, when two structures attained a comparable lateral displacement, a527

smaller residual displacement would be obtained for the structure with the higher post-yield528

stiffness ratio. Therefore, the post-yielding stage of the tested columns up to the column peak529

strength was evaluated using two post-yield stiffness indices. The first index was the ratio

530

between the column post-yield stiffness and elastic stiffness (k=k1/k2 %), where the starting point531

of the post-yield stiffness of all tested columns was defined as the theoretical strength of the532

control specimen CS-2% defined previously using AASHTO 2012, whereas the end point was

533

that corresponding to the maximum achieved lateral strength of the considered specimen (i.e., at534

a lateral load of VP and the corresponding lateral displacement δP1, see Fig. 2). By defining the535

post-yield stiffness using the aforementioned start and end points, the curvature in the hardening

536

zone of the load-displacement curves was idealized to a straight line. The second measure was537

the column displacement ductility, corresponding to the end point of the hardening zone (i.e.,538µP1=δP1 /δPy). The two indices were calculated for all specimens and are summarized in Table 5.

539

A detailed explanation concerning the efficiency of the proposed FSRC column design to540- 24 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

achieve the desired level of lateral strength (the strength of column CS-4%=67 kN) as well as the541

effect of the investigated parameters on the post-yield stiffness behavior is as follows:

542

Fig. 10.a and Table 5 illustrate that control specimen CS-2% continuously increased in lateral543

strength with the increase in the applied displacement up to a ductility of 5.3 (i.e., µP1=5.3). The

544

achieved post-yield stiffness ratio corresponding to this final ductility of the hardening zone was545

7.8%. Through wrapping the plastic hinge zone with an FRP jacket, as in column CS-2%-J, the546

column showed an ability to receive a greater lateral load up to µP1 of 9.0, but the post-yield547

stiffness ratio decreased to 6.6%. A substantial decrease in the column post-yield stiffness ratio548

of approximately 35% was observed when increasing the amount of steel reinforcement, as in

549

column CS-4%. In contrast, a significant increase in the post-yield stiffness ratio was observed

550

when adding FRP bars, as shown in Fig. 10. Fig. 10.b illustrates that column CSF-2.8%-IS-D10

551

had a value of k more than twice that of column CS-2%, although the two columns share nearly552

the same value of µP1. Changing the location of the FRP bars from the place of the steel fibers

553(column CSF-2.8%-IS-D10-J) to outside the steel stirrups (in the concrete covers, such as in554

column CSF-2.8%-ES-D10-J) resulted in a 30% increase in the value of µP1 and a 17% decrease555

in the value of k, as shown in Fig. 10.c. Furthermore, by adding cross ribs to the surface of the556

FRP bars, as in column CSF-2.8%-IR-D10-J, the value of k decreased from 17.3% to 12%,557

although µP1 shifted from 5.8 to 11.3 (see Fig. 10.d). This gives a high responsibility to the558

surface texture of the FRP bars to control the length of the hardening zone. Finally, the post-yield559

stiffness represented by the two indices could be increased by using FRP bars with smaller cross-560

sectional areas. For instance, columns CSF-2.8%-ES-D10-J and CSF-2.8%-ES-D8-J, with the561same FRP-to-steel stiffness ratio, had similar values of k, whereas µP1 shifted from 7.7 to 10.4

562

when decreasing the diameter to 8 mm. This confirmed the previous observation regarding the563- 25 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

ability of the bond conditions of FRP to concrete to control the ductility at the end point of the564

achieved post-yield stiffness. The previous discussion demonstrated that by adding FRP bars

565

with a good bonding condition to concrete (8-mm-diameter bars or rough bars), the column

566

could achieve the demanded lateral strength at high ductility levels through a stable post-yield567

stiffness. Compared with these cases, using FRP bars with a weaker bond to concrete resulted in

568

an unfavorable ductility and lateral strength at the end of the post-yield stiffness; however, it

569

results in a larger post-yield stiffness ratio.

570

Column Ductility571

In performance-based seismic design philosophies of reinforced concrete structures, the572

determination of the deformation capacity of the concrete columns, which are the main573

earthquake-resisting elements, is of paramount importance. When a structure’s earthquake-574

resistant elements are sufficiently ductile, the structure can undergo large deformations before

575

failure. This is beneficial to provide warning and give sufficient time for taking preventive

576

measures and carrying out suitable repairs to the structure, which can reduce loss of life. Aside

577

from the displacement ductility corresponding to the end point of the post-yield stiffness, as

578

explained in the previous section, three other indices were also used in this study to evaluate the579

ductility behavior and investigate the effect of the tested parameters. The first is the peak

580

strength stability factor, which measures the ability of a structure to undergo large displacements

581

after achieving the peak lateral strength and before entering the degradation zone {i.e., SI=(δP2 -582

δP1) /δy}. The second is the degradation stiffness factor, which defines the ability of a structure to583

reach its ultimate load through a gradual degradation path {i.e., K4=(Vu - VP) / (δu- δP2}. Through584

this definition, a smaller value of this index indicates a stable, smooth degradation behavior and585

vice versa. The last ductility measure is the displacement ductility factor at the ultimate lateral586- 26 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

strength (µu=δu /δy). Referring to the proposed mechanical model (Fig. 2), Table 5 summarizes

587

the ductility indices for all tested columns.

588

For the control specimen, after reaching its peak lateral load at a µP1 of 5.3, it achieved a stability589

index of SI=3.5. This means that the column maintained its peak lateral strength up to a

590

displacement ductility of 8.8 before entering the degradation zone. Following the stability zone,591

the column reached its ultimate strength at an ultimate displacement ductility, µuC, of 10.3

592

through a degradation stiffness factor, K4C, of 0.86.

593

A significant enhancement in the column ductility could be achieved by wrapping the plastic

594

hinge zone of the steel RC column with an FRP jacket. Although no clear stability zone was595

formed in column CS-2%-J {i.e., µP1(µP1+ SI) of column CS-2%}, the column fulfilled its

596

ultimate strength (i.e., Vu=0.8VP) at a displacement ductility of 14.7 (i.e., µu=1.43 µuC) through a597

degradation factor of 0.27 (i.e., K4=0.3K4C). In the absence of the FRP jacket, no pronounced

598

enhancement in the ductility indices could be achieved by adding internal smooth FRP bars to599

the longitudinal reinforcement. Moreover, the weak bond between the FRP bars and surrounding600

concrete resulted in a relatively sharp degradation curve before reaching the ultimate strength.

601

For instance, the ductility indices SI, K4, and µu of specimen CSF-2.8%-IS-D10 were 0.97, 1.3,

602

and 0.96 times the corresponding values of specimen CS-2%, respectively. Reviewing the603

ductility indices of specimens CSF-2.8%-IS-D10 -J (which had smooth FRP bars) and CSF-

604

2.8%-IR-D10-J (which had roughened FRP bars) indicated that the ductility behaviors of the two

605

columns were quite different. Whereas column CSF-2.8%-IS-D10 -J had ductility indices SI, K4,

606

and µu of 2.1, 1.4, and 9.9, respectively, the corresponding values of column CSF-2.8%-IR-D10-

607

J were 0, 4.14, and 12.3, respectively. This indicates the benefit of roughening the FRP bars to608

enhance the ultimate ductility of the column (i.e., a 25% increase in µu); however, the column

609- 27 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

suddenly failed upon reaching its peak strength as a result of the FRP rupture. Regarding the610effect of the location of the FRP bars on the ductility measurements, the results showed that611

placing the FRP bars in the concrete covers instead of in the concrete core caused the column to612

begin to degrade once it achieved its peak strength, without showing stability under the peak load.

613

Moreover, the column could reach its ultimate strength at a greater displacement ductility

614

through a smoother degradation manner. This was clearly observed in the behavior of column

615

CSF-2.8%-ES-D10-J compared to column CSF-2.8%-IS-D10-J, where the ductility indices K4616

and µu of column CSF-2.8%-ES-D10-J were 0.5 and 1.4 times those of column CSF-2.8%-IS-

617

D10-J, respectively. The reason for this might be attributed to the increase in the accumulated

618

stresses in the FRP bars when they were installed at a larger effective depth, which in turn causes619

an increase in the bond stresses between the FRP bars and concrete. Reinforcing the column with

620

8-mm-diameter FRP bars (column CSF-2.8%-ES-D8-J) caused sudden drops in the lateral621

strength, similar to the case in the specimen reinforced with roughened FRP bars (column CSF-

622

2.8%-IR-D10-J). However, the degradation curve was gradual as a result of using 3- to 8-mm-

623

diameter bars that ruptured at two different drift levels. Whereas columns CSF-2.8%-ES-D8-J

624

and CSF-2.8%-ES-D10-J share the same ultimate ductility factor, the degradation stiffness factor,

625

K4, of column CSF-2.8%-ES-D8-J was nearly three times that of column CSF-2.8%-ES-D10-J.

626

Thus, more experimental investigations on the effect of the bar surface texture (bond conditions)627

on the ductility indices, particularly the degradation behavior of columns reinforced with steel

628

and FRP bars, are required.

629

Residual Displacement

630

To evaluate the behavior of the proposed RC bridge columns after an earthquake, the residual

631

displacement index, which measures the degree of permanent displacement (the displacement of632- 28 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

the zero-crossing at unloading on the hysteresis loop from the maximum displacement), was used633

in this study as an indicator to fully quantify the performance level under seismic loading. Thus,634

the drift ratio versus normalized residual displacement of all tested columns was drawn as shown635

in Fig. 11. The normalized residual displacement was defined as the ratio of the residual

636

displacement of each column at a drift level to that of the control column at the same drift level

637(i.e., r=δr/δrC). As the value of r for a column decreases, the column becomes more recoverable

638

and reparable. Fig. 11 illustrates that although the value of r up to a drift of 1.7% (onset of FRP

639

participation) was less than one for all columns, no clear stable trend could be observed. Starting

640

from this drift ratio, a stable trend for the value of r could be observed. As expected, wrapping

641

the plastic hinge region using an FRP jacket, as in column CS-2%-J, could not control the642

residual displacement of the column, where the value of r ranged from 0.95 to 1.02 up to a drift643

of 8%, at which the control column failed. By contrast, reinforcing the columns with FRP bars

644

clearly decreased the residual displacement. For instance, the average value of the normalized

645

residual displacement of columns CSF-2.8%-IS-D10, CSF-2.8%-IS-D10-J, and CSF-2.8%-ES-

646

D10-J, reinforced with FRP bars having smooth surface textures, was approximately 0.8. The

647

columns maintained this normalized value up to a drift level just before entering the degradation

648

zone of each column as a result of bond failure. Following this drift level, the FRP bars could not649

continue controlling the residual displacement until the end of the tests. In contrast, the impact

650

on the residual displacement became more considerable when enhancing the bond between the651

FRP bars and surrounding concrete. This trend can be observed in column CSF-2.8%-IR-D10-J

652(which had FRP bars with a rough texture) and column CSF-2.8%-ES-D8-J (which had FRP bars653

with a smaller diameter), where both columns had an average value of r=0.7. The columns

654

continued controlling the residual displacement with nearly the same value of r until the FRP

655- 29 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

bars ruptured, at which the FRP bars lost their role in controlling the column performance. As a656

concluding remark, among all of the tested columns, CSF-2.8%-ES-D8-J had the best seismic657

performance in terms of the smallest residual displacement. This performance was caused by the658high post-yield stiffness, in the plastic zone.

659

Dissipated Energy and Damping Ratio

660

Ductile structures should be able to dissipate significant energy during major seismic events

661

before failure. In recent decades, two indices have been defined to describe the ability of a662

structure to dissipate earthquake energy and hence survive major seismic events. The first index663

is the cumulative dissipated energy, which is computed by summing up the areas enclosed by the664

hysteretic loops in the lateral load-displacement relationships of the structure up to failure. The

665

other index is the viscous damping ratio, which reflects the damage level attained during

666

inelastic excursions. In this section, the cumulative dissipated energy, E, for all tested specimens667

was recorded and plotted for each drift level to further evaluate the effectiveness of the proposed668

reinforcement and investigate the effect of each tested parameter, as shown in Fig. 12. In the669

same manner, the damping ratio versus the displacement ductility were calculated and plotted for670

all specimens, as shown in Fig. 13.

671

Dissipated Energy

672

After calculating the energy dissipated by each loading cycle, the cumulative dissipated energy

673

up to each drift level was determined, and the effect of each parameter was addressed, as shown674

in Fig. 12. Fig. 12 illustrates that the investigated parameters had only a minor impact on the675

cumulative dissipated energy. All columns shared almost the same cumulative dissipated energy676

of approximately 27 kN.m up to a drift of 6%. The effects of the investigated parameters were677

apparent beyond this drift level. After a drift of 7%, no pronounced increase in the cumulated

678- 30 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

dissipated energy was observed in the control specimen, CS-2%, as a result of the cover spalling679

and bar buckling that caused the failure of the specimen. By wrapping the plastic hinge with an

680

FRP jacket, as in column CS-2%-J, the column continued dissipating more energy up to a drift of

681

9.4%, at which E was equal to 1.7EC, where EC is the total cumulative dissipated energy of the682

control specimen up to failure. Then, the rate of increase was small due to the FRP sheet bulging,

683

which led to the failure of that column. Fig. 12 also illustrates that although adding FRP bars to684

the steel reinforcement caused a substantial increase in the post-yield stiffness ratio, the column

685

was able to dissipate more energy up to failure. The aforementioned observations suggest that686

the efficiency of reinforcing the columns with both steel and FRP bars on the amount of

687

dissipated energy may be controlled by other variables. Thus, further investigations are still688

needed to determine the best configuration and best surface treatment to optimize the dissipated689

energy.

690

Equivalent Viscous Damping Ratio

691

The equivalent viscous damping, ζi, for the first cycle of all loading sets was calculated using692

equation 2 (Elmenshawi and Brown 2010).

693

ζi

⁄(

(2)

694

where Ei and Esi refer to the dissipated energy and elastic energy in the cycle i, respectively.

695

Fig. 13 shows the effect of each testing parameter on the relationship between the displacement696

ductility, µ, and calculated damping ratio, ζ%. Fig. 13 illustrates that up to a displacement697

ductility of two, only slight differences in the damping ratio, ζ, were observed in all columns,

698

where at this ductility, the average value of ζ was approximately 12%. There was a small699

decrease in the ζ for specimen CS-2%-J compared to the control specimen CS-2%, particularly

700

after a displacement ductility of 9, at which the concrete cover of column CS-2% spalled, as

701- 31 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

shown in Fig. 13.a. A comparison of the results of column CSF-2.8%-IS-D10 with the control

702

column (see Fig. 13.b) indicates that the decrease in ζ was more evident up to a displacement703

ductility of 9, at which both the columns started to degrade; the average loss in the value of ζ in704

this column was approximately 20%. Moreover, the comparison of the results of columns CSF-

705

2.8%-IS-D10-J and CSF-2.8%-IR-D10-J with that of column CS-2%-J (see Fig. 13.d) illustrates

706

that while reinforcing the column with internal smooth FRP bars resulted in a minor decrease in707

ζ up to the appearance of bond slip failure at a ductility of 8%, this decrease was more evident

708

when using roughened FRP bars (i.e., 33% decrease). For both columns, the value of ζ709

approaching the failure was closer to that of specimen CS-2%-J. The average value of ζ for I-S-

710

10-J and I-R-10-J up to failure was nearly 86% and 75% of that of specimen C-J, respectively.

711

By placing the FRP bars externally instead of internally, as in column CSF-2.8%-ES-D10-J, the712value of ζ became lower, where the average value of ζ for specimen CSF-2.8%-ES-D10-J was

713

almost 88% of that of specimen CSF-2.8%-IS-D10-J (see Fig. 13.c). Finally, Fig. 13.e illustrates

714

that using FRP bars with 8-mm-diameter caused a greater decrease in the value of ζ compared715

with the counterpart 10-mm-diameter BFRP bars. In other words, the decrease in the damping

716

ratio was more pronounced when using FRP bars with a stronger bond to the surrounding

717

concrete. This discussion demonstrates that although using FRP bars as the main reinforcement718

helped the column achieve higher levels of post-yield stiffness without causing any loss in the719

column ductility and dissipated energy, the decrease in the damping ratio could be acceptable to720

achieve the aim of damage-controlling structures.

721

Which FSRC Column Could Successfully Achieve a Ductile-Recoverable Performance?

722

In the light of the targeted structural performance of the proposed FRP-steel RC structure, two723

columns could achieve the demanded ductile-recoverable performance. The first is CSF-2.8%-

724- 32 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

IR-D10-J (which had FRP bars with rough textures and was wrapped with an FRP jacket), and725

the second is column CSF-2.8%-ES-D8-J (which had FRP bars with a smaller diameter and was

726

wrapped with an FRP jacket). Both these columns had an average value for the post-yield727

stiffness ratio of 12.6%, an average displacement ductility before load degradation of 10.85, an

728

average ultimate ductility of 12.85, and an average residual displacement of 0.7 times that of the729

steel RC columns. This performance was caused by the good bonding between the FRP bars and730

surrounding concrete.

731

Summary and Conclusions

732

In this study, an FRP-steel RC structure was proposed as a high-seismic-performance structure.

733

The mechanical model describing the performance of this structure during and after earthquake

734

actions was first discussed. Experimental tests on the effect of constant axial load and several

735

cyclic loadings were conducted on seven RC bridge columns, where two columns simulated the736

performance of steel RC bridge columns and the others showed the response of the proposed

737

BFRP-steel RC columns. The roles of several bond-based parameters, such as the diameter of the738

FRP bars, texture of the FRP bars, location of the added FRP bars, and external confinement739

using an FRP jacket, were examined through the experimental program. The following

740

conclusions could be drawn from this study:

741

1) With a proper design of the proposed FRP-steel reinforcement for concrete bridge columns, it742

is possible to withstand strong earthquakes with a targeted ductility by ensuring the existence743

of a stable post-yield stiffness without a considerable increase in the elastic stiffness.

744

Moreover, the post-earthquake reparability can be enhanced by mitigating the residual

745

displacement;746- 33 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

2) Both the surface texture configuration and the diameter of the cross section of the FRP bars

747

significantly influence the seismic performance and failure mode of FRP-steel RC bridge

748

columns. Using 10-mm-diameter BFRP bars with a rough surface texture or 8-mm-diameter749

bars with small indentations resulted in a rupture of the BFRP bars that was accompanied by a

750

sharp brittle failure after achieving a high strength level with reasonable ductility. Using BFRP

751

bars with a smooth surface texture of 10-mm diameter caused a lower and more stable peak752

strength at a smaller ductility with a smoother degradation

753

3) Changing the location of BFRP bars in the column cross section with respect to the steel754

reinforcement caused only a marginal change in the column post-yield stiffness ratio and755

column ductility before strength degradation. However, compared with adding FRP bars

756

internally in the same fibers as the steel bars, placing them in the concrete cover caused a757

considerable increase in the elastic stiffness and eliminated the stability plateau at the peak758

strength before strength degradation.

7594) External confinement of the steel RC column with BFRP sheets caused a slight increase in the760

column strength with a stable degradation stiffness and a substantial increase in the761

displacement ductility before failure.

7625) Although adding BFRP bars caused a remarkable enhancement in the plastic deformation, no763

significant decrease in the damping ratio could be observed. Moreover, a comparable

764

cumulative dissipated energy was evident.

7656) Increasing the column strength to withstand a strong earthquake using additional steel

766

reinforcement greatly increased the column elastic stiffness and decreased the column post-

767

yield stiffness ratio. In contrast, by adding FRP reinforcement, nearly the same level of lateral768- 34 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

strength could be achieved with a significant increase in the column post-yield stiffness ratio769

and without any substantial increase in the elastic stiffness.

7707) Future research should be directed toward providing a better understanding of the behavior of771

such FRP-steel reinforcements with an emphasis on the bond condition’s effect on the post-

772

peak stability, residual displacement, and degradation stiffness. Other design parameters,

773

including the FRP-to-steel stiffness ratio and transverse FRP reinforcement ratio, should also774

be examined.

775

References

776

AASHTO. (2012). AASHTO LRFD Bridge Design Specifications, American Association of

777

State Highway and Transportation Officials, Washington, D.C.

778

Christopoulos, C., Pampanin, S., and Priestley, M. J. (2003). “Performance-based seismic779

response of frame structures including residual deformations. Part I: Single-degree of freedom

780

systems.” J. Earthquake Eng., 7(1), 97–118.

781

Christopoulos, C., and Pampanin, S. (2004). “Towards performance-based seismic design of782

MDOF structures with explicit consideration of residual deformations.” ISET Journal of783

Earthquake Technology, 41(1), 53–73.

784

Dhakal, R. P., and Maekawa, K. (2002). “Reinforcement stability and fracture of cover concrete
in reinforced concrete members.” J. Struct. Eng., 128(10), 1253-1262.
Elmenshawi, A., and Brown, T. (2010). “Hysteretic energy and damping capacity of flexural
elements constructed with different concrete strengths.” J. Eng. Struc., 32(1), 297-305.

785
786
787
788

Fahmy, M. F. M., Wu, Z. S., and Wu, G. (2009). “Seismic performance assessment of damage789

controlled FRP-retrofitted RC bridge columns using residual deformations.” J. Compos.

790

Constr., ASCE, 13(6):498-513.

791- 35 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Fahmy, M. F. M., Wu, Z. S., and Wu, G., (2010) “Post-earthquake recoverability of existing RC

792

bridge piers retrofitted with FRP composites.” Constr. and Building Mater., 24(6), 980-998.

793

Iemura, H., Takahashi, Y., and Sogabe, N. (2006). “Two-level seismic design method using post-

794

yield stiffness and its application to unbonded bar reinforced concrete piers.” Struct.

795

Eng./Earthquake Eng., 23(1), 109s–116s.

796

Ikeda, S., Nonaka, S., Hirose, S., and Yamagushi, T. (2002) “Seismic performance of concrete

797

piers prestressed in the critical section.” In: Proceedings of the First FIB Congress, Osaka,

798

Japan, 47-48.

799

Kawashima, K. (2000). “Seismic design and retrofit of bridges.” Bull. New Zeal. Natl. Soc.
Earthquake Eng., 33(3), 265–285.

800
801

Kawashima, K., MacRae, G. A., Hoshikuma, J., and Nagaya, K. (1998). “Residual displacement
response spectrum.” J. Struct. Eng., 124(5), 523–530.

802
803

Mazzoni, S., McKenne, F., Scott, M. H., Fenves, G. L. et al. Open system for earthquake804

engineering simulation user manual version 2.4.5. Berkeley (CA): Pacific Earthquake

805

Engineering Center, University of California. http:// http://opensees.berkeley.edu/

806

Palmieri, A., Matthys, S., and Tierens, M. (2009). “Basalt fibers: mechanical properties andapplications for concrete structures.” Taylor & Francis Group, London, UK, 165-169.

807
808

Pettinga, D., Christopoulos, C., Pampanin, S., and Priestley, N. (2007). “Effectiveness of simple

809

approaches in mitigating residual deformations in buildings.” Earthquake Eng. Struct. Dyn.,

810

36(12), 1763–1783.

811

Priestley, M., Seible, F., and Calvi, G. M. (1996). Seismic design and retrofit of bridges, Wiley,
New York.

812
813- 36 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Saiidi, M. S., O’Brien, M., and Zadeh, M. S. (2009). “Cyclic response of concrete bridge
columns using superelastic nitinol and bendable concrete.” ACI Struct J., 106(1), 69-77.

814
815

Sakai, J., Jeong, H., and Mahin, S.a. (2006) “Reinforced concrete bridge columns that re-center

816

following earthquakes.” In: Proceedings of the 8th National conference on Earthquake

817

Engineering, San Francisco, CA, paper no. 1421.

818

Sim, J., Park, C., and Moon, D.Y. (2005). “Characteristic of basalt fiber as a strengthening
material for concrete structures.” Composites: Part B Eng., 36(6), 504-512.
Wehbe, N. I., Saiidi, M. S., and Sanders, D. H (1999). “Seismic Performance of Rectangular
Bridge Columns with Moderate Confinement.” ACI Struct J., 96(2), 248-258
Wu, Z. S., Fahmy, M. F. M., and Wu, G. (2009). “Safety enhancement of urban structures withstructural recoverability and controllability.” J. Earthquake Tsunami, 3(3), 143–174.

819
820
821
822
823
824

Wu, G.,Wu, Z. S., Luo, Y. B., Sun, Z. Y., and Hu, X. Q. (2010). “Mechanical properties of steel-

825

FRP composite bar under uniaxial and cyclic tensile loads.” J. Mater. Civ. Eng., 22(10),8261056–1066.

827

Wu, Z., Wang, X., Iwashita, K., Sasaki, T., and Hamaguchi, Y. (2010). “Tensile fatigue behavior
of FRP and hybrid FRP sheets.” Composites: Part B Eng., 41(5), 396-402.
Zatar, W. A., and Mutsuyoshi, H. (2002). “Residual displacement of concrete bridge piers
subjected to near field earthquakes.” ACI Struc. J., 99(6), 740-749.

828
829
830
831

Figure captions

832

Fig. 1. Schematic model of: a) proposed FSRC structure and b) conventional SRC structure

833(SRC1 and SRC2).

834- 37 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Fig. 2. Targeted idealized load deformation behavior of the proposed FRP-steel RC column

835

versus steel RC columns, based on the damage-controlled model for existing RC structures

836(Fahmy et al. 2009).

837

Fig. 3. Typical test unit (dimensions are in mm) and instrumentation of a test specimen

838

Fig. 4. Cross sections and reinforcement details of specimens (dimensions are in mm).

839

Fig. 5. Configuration of the surface texture of FRP bars.

840

Fig. 6. Typical arrangement of strain gauges.

841

Fig. 7. Load versus drift ratio curves of column specimens.

842

Fig. 8. State of the column specimens at failure.

843

Fig. 9. Load versus BFRP bar strain of FSRC columns.

844

Fig. 10. Effect of the investigated parameters on the average envelope response.

845

Fig. 11. Normalized residual displacement versus lateral drift ratios of the tested columns.

846

Fig. 12. Effect of all investigated parameters on the cumulative dissipated energy.

847

Fig. 13. Effect of all investigated parameters on the damping ratio.

848
849
850
851
852
853
854
855
856
857
858

- 38 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Table 1. Mechanical properties of steel and FRP materials
Material typeLongitudinal steel bars
Transverse steel bars
10 mm diameter BFRP bars
8 mm diameter BFRP bars
BFRP sheet

859

Elastic modulus Yield stress Tensile strength
E (GPa)fy (MPa)
fu (MPa)
200
200
48.1
47.3
91

375
400
-------------------

560
625
1113
1086
2100

Note: (1) Tensile strengths of the BFRP bars were defined based on the cross-sectional area of

860

each bar. (2) Based on the manufacturer, the basalt fiber content was 60% of the cross-sectional

861

area.

862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879

- 39 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Table 2. Experimental Parameters

880

Steel reinforcement

Specimen

BFRP reinforcementρl %fc′ (MPa)
numberMain

Transverse

Location

SurfaceComponents

Lj1
(mm)

CS-2%

27.8

6Φ13

Φ6@50 mm-----------------

2-----

CS-2%-J

31.4

6Φ13

Φ6@50 mm-----------------

2

300

CSF-2.8%-IS-D10

35.4

6Φ13

Φ6@50 mmInternal

Smooth

4Φ10

2.8

-----

CSF-2.8%-IS-D10-J

41.2

6Φ13

Φ6@50 mmInternal

Smooth

4Φ10

2.8

300

CSF-2.8%-IR-D10-J

32.9

6Φ13

Φ6@50 mmInternal

Roughened

4Φ10

2.8

300

CSF-2.8%-ES-D10

32.7

6Φ13

Φ6@50 mm

External

Smooth

4Φ10

2.8

600

CSF-2.8%-ES-D8

34.5

6Φ13

Φ6@50 mm

External

Smooth

6Φ8

2.8

600

Note: fc ′ is the actual concrete compressive strength on the day of testing; ρl is the total

881

reinforcement ratio of the steel and FRP bars; Lj1 is the length of the first 0.333-mm-thick FRP

882

jacket above the column base.

883
884
885
886
887
888
889
890
891
892
893
894
895

- 40 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Table 3. Positive and negative characteristic values of the hysteretic curves of the tested columns
Specimen number
CS-2%
CS-2%-J
CSF-2.8%-IS-D10
CSF-2.8%-IS-D10-J
CSF-2.8%-IR-D10-J
CSF-2.8%-ES-D10-J
CSF-2.8%-ES-D8-J

Vy
(kN)

δy
(mm)

εfy
(µε)

VP
(kN)

δP1
(mm)

δP2
(mm)

δu
(mm)

εfu
(µε)

+26.0

+5.4

-------+37.3+30.0 +50.0 +29.8 +58.5

----

-26.8

-6.0

-------

-37.8

-30.0

-59.0

----

+27.2

+5.6

-------+43.3+50.0 +50.0 +34.6 +83.2-------

-50.1
-50.0

Vu
(kN)
-30.2
-34.8

-80.0

896

Failure mode
Cover spalling andbar buckling
Fracture ofsteel bars

-27.6

-5.5

-------

-43.5

-50.0

+30.8

+7.9

+2032

+48.0

-27.6

-6.3

-1888

-50.0

+30.0 +59.9 +37.5 +70.1 +10972 Local bond slip of
FRP bars-41.3 -59.9 -37.5 -70.1 -13908

+28.1

+5.3

+1748 +56.75

+50

-36.7

-9.6

-2512

-59

+59.1 +37.5 +70.0 +12283 Local bond slip of
FRP bars-40.0 -58.7 -37.5 -76.9 -13160

+29.4

+6.5

+2019

+60.0

+69.7 +69.7 +37.5 +76.4

-28.1

-5.9

-2192

-69.0

-70.1

+33.2

+5.7

+2292

+61.0

+40.8 +40.8 +37.5 +80.0

-70.1
-50.0

-37.5

-30.8

-5.8

-1982

-60.0

-48.0

+32.9

+6.0

+2911

+68.0

+60.0 +60.0 +37.5 +80.0

-31.9

-5.6

-2603

-71.0

-60.0

-60.0

-37.5

-76.4

-37.5

-80.0
-74.9

----16330----14152----22272

Rupture of
FRP bars
Local bond slip of
FRP bars
Rupture of
FRP bars

Note: the symbols “+” and “-” stand for the characteristic values in the positive and negative

897

loading directions, respectively.

898
899
900
901
902
903
904
905
906
907
908
909
910

- 41 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Table 4. Average characteristic values of the hysteretic curves of the tested columns
Specimen number

Vcr
(kN)

δcr
(mm)

Vy
(kN)

δy
(mm)

εfy
(µε)

VP
(kN)

δP1
(mm)

δP2
(mm)

Vu
(kN)

δu
(mm)

εfu
(µε)

CS-2%

9.2

0.9

26.4

5.7

-------

37.5

30.0

50.1

30.0

58.8

-------

CS-2%-J

9.4

1.0

27.4

5.5

-------

43.4

50.0

50.0

34.7

81.6

-------

CSF-2.8%-IS-D10

10.0

1.3

29.2

7.1

1960

49.0

35.6

59.9

37.5

70.1

12440

CSF-2.8%-IS-D10-J

10.6

1.2

32.4

7.4

2130

57.1

45

58.9

37.5

73.4

12721

CSF-2.8%-IR-D10-J

10.7

1.2

28.8

6.2

2106

64.5

69.9

69.9

37.5

76.4

16330

CSF-2.8%-ES-D10-J

12.6

1.1

32.0

5.8

2137

60.5

44.4

45.4

37.5

80.0

14152

CSF-2.8%-ES-D8-J

12.7

1.0

32.4

5.8

2757

69.5

60.0

60.0

37.5

77.5

22272

911

912
913
914
915
916
917
918
919
920
921
922
923
924

- 42 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Table 5. Ductility and stiffness indices of the investigated columns
Stiffness indicesSpecimen number

925

Ductility indicesK1(kN/mm)K2(kN/mm)

k (%)

µP1
K4
SI (mm/mm)(mm/mm)(kN/mm)µu(mm/mm)

CS-2%

4.6

0.36

7.8

5.3

3.5

0.86

10.3

CS-2%-J

4.9

0.33

6.6

9.0

0.0

0.27

14.7

CSF-2.8%-IS-D10

4.1

0.69

16.7

5.0

3.4

1.14

9.9

CSF-2.8%-IS-D10-J

4.4

0.76

17.3

5.8

2.1

1.40

9.9

CSF-2.8%-IR-D10-J

4.6

0.56

12.0

11.3

0.0

4.14

12.3

CSF-2.8%-ES-D10-J

5.5

0.80

14.4

7.7

0.0

0.65

13.8

CSF-2.8%-ES-D8-J

5.6

0.73

13.1

10.4

0.0

1.83

13.4

CS-4%

9.6

0.48

5.0

10.0

------

----

10.0

926
927

- 43 -

Figure 1
Click here to download Figure: Fig. 1.pdf
茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Steel stirrups

Concrete

Steel
bars

Steel stirrups

Concrete

Steel bars
C

C
Section C-C

FRP sheet

FRP sheet

FRP bars

Steel bars

Section A-A(Structure SRC2)

Steel bars
Steel stirrups
FRP bars
B

B
Steel bars
Section B-B

A

Section A-A A(Structure SRC1)

(b)

(a)

Fig. 1. Schematic model of: a) proposed FSRC structure and b) conventional SRC structure(SRC1 and SRC2)- 44 -

Figure 2
Click here to download Figure: Fig. 2.pdf

Moderateshaking

Lateral load

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Serviceability
state
No repair

Damage-Controllable state
Dilatory repair
Strong shaking with rare
probability

Peak load(VP) Y2

Stability in peak load(with zero stiffness (K3))

VP2
M2

I2

Ultimate state
Repair of damaged parts
while structure usable byemergency vehicles

S

M

Long-time
repair or
replacement ofstructuralelements
Gradualdegradation

Yielding load
Post-yield stiffness
K2

Y

VP1

I1

F2

K4

Maintaining peak load ofcolumn SRC1
(Vu= VP1)

F1

Zone 4

Zone 3

C2

F

M1

Yielding load
(Vy)

Y1

Cracking load
(Vcr)

I

Zone 2
C
C1
Zone 1
K1High ductilityδyδrδr1 δr2

δP1

δI

δu

Lateral displacement

Decrease in residual displacement
SRC1

δP2

SRC2

Proposed FSRC

Fig. 2. Targeted idealized load deformation behavior of the proposed FRP-steel RC column
versus steel RC columns, based on the damage-controlled model for existing RC structures(Fahmy et al. 2009)- 45 -

Figure 3
Click here to download Figure: Fig. 3.pdf
茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Prestressing bar
Fixed wall
Load cell

LVDT

Lj1

BFRP bar (8 or 10 mm)
BFRP jacket (0.333 mm thick.)Φ6@50 mm200

6Φ13 mm
BFRP jacket
mm(0.666 mm thick.)

700

Load
cell

300

Hydraulic
jack

850

Reversedcyclic load500

6Φ19 mmmm
Φ10@150 mm
Strong ground floor
1000

Fig. 3. Typical test unit (dimensions are in mm) and instrumentation of a test specimen- 46 -

Figure 4
Click here to download Figure: Fig. 4.pdf
茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター(b) CS-2%-J

200
160

200
160

Steel bars
(6Φ13 mm)
Φ6@50
mmmm
BFRP bars(4Φ10 mm)mm
BFRP
jacket(d) CSF-2.8%-IS-D10-J(e) CSF-2.8%-IR-D10-J

Φ6@50 mm200

BFRP jacket
BFRP bars (4Φ10 mm)mm(c) CSF-2.8%-IS-D10
Steel bars
(6Φ13
mm)
Steel bars
mm
(6Φ13 mm)mm
BFRP bars(4Φ10 mm)mm
BFRP
jacket(f) CSF-2.8%-ES-D10-J

200
160

BFRP jacket
Φ6@50 mm200(a) CS-2%

200
160

200
160

Φ6@50 mm

200
160

160

200
160

200
160

Steel bars
(6Φ13 mm)mm
Φ6@50 mmSteel bars
(6Φ13 mm)Steel bars mm(6Φ13 mm)mm
Φ6@50 mm

160

200
160

200
160

BFRP bars(6Φ8 mm)mm(g) CSF-2.8%-ES-D8-J

Fig. 4. Cross sections and reinforcement details of specimens (dimensions are in mm)- 47 -

Figure 5
Click here to download Figure: Fig. 5.pdf
茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

10.00

3.00

(a) 8-mm-diameter BFRP bar with surface having small indentations (smooth D8)
bar)
8.00
3.00

(b) 10-mm-diameter BFRP bar with surface having small indentations (smooth D10)
bar)
11.00

(c) 10-mm-diameter BFRP bar with cross roughened surface (rough D10 bar)
Fig. 5. Configuration of the surface texture of FRP bars

- 48 -

Figure 6
Click here to download Figure: Fig. 6.pdf
茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

F-4

S-4 S′-4

F′-4
F′-3
F′-2

100
F-3

S-3 S′-3

50

F-2

50

F-1

S-2 S′2
S-1 S′-1

BFRP bar

F′-1

Steel bar

Fig. 6. Typical arrangement of strain gauges- 49 -

Figure 7
Click here to download Figure: Fig. 7.pdf

70
60
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
-70

µ = 10.3µ = 8.8 µ = 5.3

70
60
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
-70

µ = 8.8

Vy = 26.4 kN and δy=5.7 mm
VP = 37.5 kN
Vu = 30 kNµP1 = 5.3 and SI= 3.5µu = 10.3µ= 1µ = 5.3µ = 10.3µ = 12.3

Lateral load (kN)

Lateral load (kN)

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Steel yielding
Concrete cover bulking
Concrete cover spalling
Steel bar buckling
Ultimate pointµ= 1

Vy = 27.4 kN and δy=5.6 mm
VP = 43.4 kN
Vu = 34.6 kNµP1 = 8.9 and SI= 0.0µu = 14.7µ = 14.3

Steel yielding
FRP jacket bulging out
Steel bar buckling
Steel bar rupture
Ultimate pointµ= 1µ =8.9-11-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 1170µ = 8.5µ = 4.2
60 Vy = 29.2 kN and δy=7.1 mmµ = 9.9µ= 1
50 VP = 49 kN
40 Vu = 37.5 kNµ = 11.3
30 µP1 = 5.0 and SI= 3.4
20 µu = 9.9
10
0
-10
-20
Steel yielding-30 µ = 11.3
First FRP bond failure-40
Last FRP bond failure-50µ = 9.9µ= 1
Steel bar rupture-60µ = 8.5 µ = 5.6
Ultimate point-70-11-10-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
Drift ratio (%)

70µ = 6.8 µ = 8.1
60 Vy = 32.4 kN and δy=7.4 mmµ = 9.5µ= 1
50 VP = 57.1 kNµ = 10.8
40 Vu = 37.5 kN
30 µ = 5.8 and SI= 2.1
20 µP1= 9.9
u
10
0
-10
-20
Steel yielding-30
First FRP bond failure-40 µ = 10.8
Last FRP bond failure-50
Steel bar ruptureµ= 1µ = 9.5-60
Ultimate pointµ = 8.1 µ = 5.4-70-11-10-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
Drift ratio (%)(c) CSF-2.8%-IS-D10µ = 11.3µ = 12.3µ= 1µ = 11.3µ= 1

Steel yielding
FRP bar rupture
Steel bar rupture
Ultimate point

Lateral load (kN)

Vy = 28.8 kN and δy=6.2 mm
VP = 64.5 kN
Vu = 37.5 kNµP1 = 11.3 and SI= 0.0µu = 12.3(d) CSF-2.8%-IS-D10-J

70
60
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
-70

Vy = 32 kN and δy=5.8 mm
VP = 60.5 kN
Vu = 37.5 kNµP1 = 7.6 and SI= 0.0µu = 13.8µ = 13.8µ = 10.3µ= 1µ = 8.6µ = 6.7µ= 1µ = 10.3µ = 13.8

Steel yielding
FRP bond failure
Partial rupture of FRP bars
Steel bar rupture
Ultimate point-11-10-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
Drift ratio (%)-11-10-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
Drift ratio (%)(e) CSF-2.8%-IR-D10-J(f) CSF-2.8%-ES-D10-J

Lateral load (kN)

70
60
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
-70

Drift ratio (%)(b) CS-2.0%-J

Lateral load (kN)

Lateral load (kN)

µ = 14.3-11-10-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
Drift ratio (%)(a) CS-2.0%

Lateral load (kN)

µ = 14.7µ = 8.9µ= 1

70µ = 10.3µ = 1260 Vy = 32.4 kN and δy=5.8 mmµ= 1µ = 13.8
50 VP = 69.5 kN
40 Vu = 37.5 kN
30 µP1 = 9.4 and SI= 0.0
20 µu = 12.1
100
-10Steel yielding-20
Rupture of one FRP bars
-30
-40 µ = 12.1
Rupture of other FRP bars
-50
Steel bar ruptureµ= 1-60 µ =12µ = 10.3
Ultimate point-70-11-10-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
Drift ratio (%)(g) CSF-2.8%-ES-D8-J
Fig. 7. Load versus drift ratio curves of column specimens- 50 -

Figure 8
Click here to download Figure: Fig. 8.pdf
茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

Concretespalling and

Rupture ofsteel barsteel bar buckling(a) CS-2%

Buckling ofsteel bar(b) CS-2%-J

Buckling of Local bondsteel bar failure of BFRP

Local bond
Rupture ofsteel bar failure of BFRP
bar

bar

(c) CSF-2.8%-IS-D10(d) CSF-2.8%-IS-D10-J

Rupture of
BFRP barRupture ofsteel bar(e) CSF-2.8%-IR-D10-J(f) CSF-2.8%-ES-D10-J
Rupture of
BFRP barRupture ofsteel bar(g) CSF-2.8%-ES-D8-J

Fig. 8. State of the column specimens at failure- 51 -

Partial ruptureof FRP bar

Figure 9
Click here to download Figure: Fig. 9.pdf

70
60
50
40
µ = 9.9
30
20
10
0
-10
-20
-30
-40
-50
-60
-70
-10000 -5000

70
60
50
µ= 1
40
30
20
10
0
εr
-10
-20
-30
-40
-50
-60
-70
0
5000 10000 15000 20000 25000 -10000 -5000
BFRP bar strain (µε)µ = 4.2µ = 8.5 (0.54εr)µ = 9.5εr

05000 10000 15000
BFRP bar strain (µε)

20000

0

70
60
50
40
µ= 1
30
µ = 11.3 (0.71εr)
20
10
0
εr
-10
-20
-30
-40
-50
-60
-70
5000 10000 15000 20000 25000 -10000 -5000
BFRP bar strain (µε)(e) CSF-2.8%-IR-D10-J(at 150 mm above column base, F-4)706050
µ = 12
40
30
20
10
0
-10
-20
-30
-40
-50
-60
-70
-10000 -5000
0

25000

(d) CSF-2.8%-IS-D10-J(at 50 mm above column base, F-3)
µ = 6.7 (0.61εr)µ =10.3

Lateral load (kN)µ= 1

Lateral load (kN)

Lateral load (kN)(c) CSF-2.8%-IS-D10(at 50 mm above column base, F-3)
70
60
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
-70
-10000 -5000µ = 8.1 (0.56εr)µ= 1Lateral load (kN)

Lateral load (kN)

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

εr

05000 10000 15000
BFRP bar strain (µε)

20000

25000

(f) CSF-2.8%-ES-D10-J(at 50 mm above column base, F-3)µ= 1

µ = 10.3µ = 12(0.94εr)εr5000 10000 15000 20000 25000
BFRP bar strain (µε)(g) CSF-2.8%-ES-D8-J(at 50 mm above column base, F-3)
Fig. 9. Load versus BFRP bar strain of FSRC columns- 52 -

Figure 10
Click here to download Figure: Fig. 10.pdf

70

70

60

60

50

50

Lateral load (kN)

Lateral load (kN)

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

40
Theoretical strength30

Onset of concrete cover spalling
Onset of steel bar buckling
Onset of FRP jacket bulging out
Ultimate point

20
10

CS-2%
CS-2%-J

40

30

Onset of cover spalling
Onset of steel bar buckling
FRP bond failure
Compression failure
Ultimate point

20
10
0

0

0

1

2

3

4
5
6
Drift ratio (%)

7

8

9

10

0

11

70

60

60

50

50

Lateral load (kN)

Lateral load (kN)

70

40
30
20

First FRP bond failure
Last FRP bond failure
Ultimate point

10

1

2

3

4

5

6

7

8

9

10

11

Drift ratio (%)(b) Effect of adding
smooth FRP bars(a) Effect of FRP wrapping

40
30

Onset of steel bar buckling
FRP bond failure
FRP bar rupture
Ultimate point

20

CSF-2.8%-IS-D10-J

CS-2%-J

CSF-2.8%-IS-D10-J

10

CSF-2.8%-ES-D10-J

0

CSF-2.8%-IR-D10-J

0

0

1

2

3

4

5

6

7

8

9

10

0

11

70

60

60

50

50

Lateral load (kN)

70

40

30

FRP jacket bulging out
First FRP bond failure
Last FRP bond failureFirst FRP rupture
Last FRP rupture
Ultimate point20

10

CS-2%-J

1

2

3

4

5

6

7

8

9

10

11

ratiosurface(%)(d) Effect of FRP Drift
bar’s
configuration

ratio (%) of FRP bars(c) Effect ofDriftlocation

Lateral load (kN)

CS-2% (Num.)
CS-2%
CSF-2.8%-IS-D10
CS-4% (Num.)CSF-2.8%-ES-D10-J

Stability in peak load

40
30
CS-2%
CSF-2.8%-IS-D10
CSF-2.8%-IS-D10-J

20

10

CSF-2.8%-ES-D8-J

0

0

0

1

2

3

4
5
6
Drift ratio (%)

7

8

9

10

11

(e) Effect of FRP bar’s diameter

0

1

2

3

4
5
6
Drift ratio (%)

7

8

9

10

(f) Columns contained stability plateau

Fig. 10. Effect of the investigated parameters on the average envelope response- 53 -

11

Figure 11
Click here to download Figure: Fig. 11.pdf

Normalized Residual displacement,r

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

1
0.9

0.8
0.7
C
I-S-10I-R-10-J
E-S-8-J

0.6

C-J
I-S-10-J
E-S-10-J

0.5
0

1

2

3
4
5
Drift ratio (%)

6

7

8

Fig. 11. Normalized residual displacement versus lateral drift ratios of the tested columns- 54 -

Figure 12
Click here to download Figure: Fig. 12.pdf
茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

80
CS-2%
CS-2%-J

70

Cumulative dissipated energy, E(kN.m)

Cumulative dissipated energy, E(kN.m)

80

60

50
40
30
20
10

70

50
40
30

20
10

0
0

1

2

3

4
5
6
Drift ratio (%)

7

8

9

10

CS-2%
CSF-2.8%-IS-D10

60

0

11

0

(a) Effect of FRP wrapping

2

3

4
5
6
Drift ratio (%)

7

8

9

10

11

(b) Effect of adding smooth FRP bars

80

CSF-2.8%-ES-D10-J

60

CSF-2.8%-IS-D10-J

50

CS-2%-J

Cumulative dissipated energy, E(kN.m)

80

70

40
30
20
10

70

CS-2%-J
CSF-2.8%-IS-D10-J
CSF-2.8%-IR-D10-J

60
50
40
30
20
10

0

0

0

1

2

3

4
5
6
Drift ratio (%)

7

8

9

(c) Effect of location of FRP bars

10

11

0

1

2

3

4
5
6
Drift ratio (%)

7

8

9

10

70
CS-2%-J
CSF-2.8%-ES-D10-J
CSF-2.8%-ES-D8-J

60

50
40

30
20

10
0
0

1

2

3

11

(d) Effect of FRP bar’s surface configuration

80

Cumulative dissipated energy, E(kN.m)

Cumulative dissipated energy, E(kN.m)

1

4
5
6
Drift ratio (%)

7

8

9

10

11

(e) Effect of FRP bar’s diameter
Fig. 12. Effect of all investigated parameters on the cumulative dissipated energy- 55 -

Figure 13
Click here to download Figure: Fig. 13.pdf

40

40

30

30

20

CS-2%
CS-2%-J
10

Damping ratio, ζ (%)

Damping ratio, ζ (%)

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

20

10

CS-2%
CSF-2.8%-IS-D10

0

0

1

2

3

4

5

6 7 8 9 10 11 12 13 14 15
ductility µ(a) Effect ofDisplacement
FRP wrapping

0

30

30

CS-2%-J
10

CSF-2.8%-ES-D10-J

Damping ratio, ζ (%)

40

20

1

2

3

4

5

6 7 8 9 10 11 12 13 14 15
Displacement ductility µ(b) Effect of adding smooth FRP bars

40

20

CS-2%-J
CSF-2.8%-IS-D10-J
CSF-2.8%-IR-D10-J

10

CSF-2.8%-IS-D10-J
0

0
0

1

2

3

4

5

0

6 7 8 9 10 11 12 13 14 15
Displacement ductility, µ(c) Effect of location of FRP bars

1

2

3

4

5

6 7 8 9 10 11 12 13 14 15
Displacement ductility, µ(d) Effect of FRP bar’s surface configuration

40

Damping ratio, ζ (%)

Damping ratio, ζ (%)

0

30

20
CS-2%-J
CSF-2.8%-ES-D10-J
CSF-2.8%-ES-D8-J

10

0
0

1

2

3

4

5

6 7 8 9 10 11 12 13 14 15
Displacement ductility, µ(e) Effect of FRP bar’s diameter
Fig. 13. Effect of all investigated parameters on the damping ratio- 56 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター- 57 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター- 58 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター- 59 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター- 60 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター- 61 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター- 62 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター- 63 -

Ⅱ.プロジェクト業績

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

1. 活動内容【都市インフラの強靭化技術開発】
炭素繊維やパサルト繊維による構造補強材の高性能化により、インフラ構造物の耐震性やResilience（自己回復性）向上手法を開発し、都市インフラの強靭化技術に関する取り組みを行っており、産学連携を検討している。（呉教授）【都市インフラモニタリングや知能化による高度化センサ技術の開発】
1) 光ファイバセンサ方式とカーボンファイバセンサ方式による長寿命・高性能化された分
布型領域センサの実製作・性能究明および実用性を実験室レベルで検討した。
２）領域センサにより得られるひずみ分布の直接利用により、構造物の早期損傷検知に対する各種指標を検討した。
３）開発したセンサ、装置、検知アルゴリズムを基に、早期損傷検知システムを開発し、茨城県内の RC 桁橋、新潟県内の既損傷 PC 箱桁橋、東北新幹線高架橋、中国の蘇通大橋（１０００ｍ級長大橋）など既設構造物のリアルタイム健全性評価システムの検証を進めている。
４）高度化された光ファイバ分布センシング技術による広域地圏環境（河川堤防・地すべり）防災システムの構築に関する産官学連携プロジェクトを開始し、基礎検討を行っている。
（呉教授）【センサデータの安定した通信/解析技術の開発と省電力化推進】
1) 大規模災害により、電源インフラが完全消失した状況において、市民にどのように、情報を伝達するか、また市民の安否情報をどのように収集するかについて研究を進めている。内部電源を必要としない UHF 帯 RFID を利用している。（武田教授）【老朽化したインフラ構造物の災害リスクを考慮した維持管理計画】
1) 橋梁の（異常監視）ヘルスモニタリングシステムの実証実験を常陸大宮市の引田橋での継続的に実施した。（齋藤特命教授,原田准教授, 鎌田教授）
2) ひたちなか海浜鉄道湊線での企業との傾斜計の実証実験を推進．本件は 10 月に茨城県土木部との連携で常陸大宮地区の地すべり危険地域への応用予定（齋藤特命教授）
3) 構造物の耐久性設計に資する高度化シミュレーション技術を開発している（車谷准教授）- 64 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター【UAV を活用した新たな空間情報の防災システムへの活用と超小型衛星との連携】
1) 茨城県生活安全部と UAV による安全監視・不法投棄防止システムの実現の連携検討を開始した。（齋藤特命教授）
2) 宮城教育大学との UAV を用いた空間環境情報可視化と津波災害地域の空撮を行った。
（齋
藤特命教授）
3) 宮城県石巻市、女川町での空撮による災害地域の土地利用変化、震災遺構の映像保存プ
ロジェクトをスタートさせた。（齋藤特命教授）【アウトリーチとしての防災・減災、それらを含む環境教育の実施】
1) 日本リモートセンシング学会との共催で、守谷市内小学校で防災における空間情報応用に関する講演を実施した。（桑原准教授）
2) ひたちなか市外野小学校、前渡小学校にて環境・情報教育を実施した。（齋藤特命教授、桑原准教授）
3) (社)次世代センサ協議会第 44 回センサ＆アクチュエータ技術シンポジウムにて UAV と防災について講演した。（齋藤特命教授）
4) 日本リモートセンシング学会との共催で、守谷市内小学校で防災における空間情報応用に関する講演を実施した。（桑原祐史准教授）【災害時および平常時等における情報共有法】
1) 防災情報を配信する方法には、インターネットやＦＭ放送、拡声器などを利用する方法があるが一長一短がある。そこで追加手段の１つとして交通信号機を配信局として用いる方法を研究している。特に、光点滅（ＬＥＤのオンオフ、人間の目ではそのオンオフは感知できない）による光ワイヤレス通信の高信頼化について検討している。
2) 大規模震災では、集中制御が基となる携帯網・ワイヤレス通信網では情報共有は難しい
また、信号機等の停電により大規模な車両渋滞が生じると考えられる。その渋滞車両を積極的に通信局として利用するネットワーク網を構築する研究を進めている。ＭＡＣプ
ロトコルとして、変形２進カウントダウン法を考案している。（羽渕裕真教授）【地元企業・学校等との学術連携実現】
1) 日立製作所と連携し、ベトナム国ダナンおよびビンディン県の防災システム構築に参加した。（桑原准教授）
2) 湊線の鉄道運行支援システム構築について、連携研究を実現（ひたちなか海浜鉄道、福山 C）した。（齋藤特命教授, 桑原准教授）- 65 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター【他大学・企業・自治体連携での研究資金獲得】
1) 東北大学と共同で申請した科研費（挑戦的萌芽）「地盤中の間隙水の挙動調査」採択（東北大学風間基樹教授, 茨城大学安原一哉名誉教授, 鎌田賢教授）（齋藤修特命教授の企
画・アレンジによる）において、地中埋め込み型の土砂内水流・水圧センサと無線モジ
ュールを開発した。
2) 日本リモートセンシング学会の後援として、仙台市（東北工業大学）にて防災に対する衛星画像利用の WS を開催した。（桑原准教授）
3) シンポジウム「SICE 計測部門セミナー 都市のスマートセンシング」を企画して開催した。（齋藤特命教授）
http://rcl.it.aoyama.ac.jp/sice-sss/sice_seminar_20140917.html【自治体との各種連絡会議推進（茨城県・日立市・ひたちなか市等）】
1) 茨城県商工労働部、土木部、企画部、生活安全部との定期情報交換（齋藤特命教授）（鎌田教授, 桑原准教授は随時参加）
2) 日立市土木部、生活環境部、市長、副市長との定期情報交換（齋藤特命教授）（鎌田教授, 桑原准教授は随時参加）
3) ひたちなか市長との情報交換会 1 回／年度（齋藤特命教授）（鎌田教授, 桑原准教授は随時参加）【国際共同研究を実施（アメリカ、英国、イタリア、中国、韓国等）】
1) 科研 S-8(安原名誉教授)におけるメコン川流域とメコンデルタの気候変動影響と災害事
情調査(UAV による調査を含む)に参画した。成果は 2014 年 8 月 30 日 NHK-TV

NHK スペシャルにて放映された。
2) センシング技術による地下鉄防災システムの高度化に関する共同研究を英国のケンブリッジ大学、長大橋の長寿命化に関する研究を中国の東南大学、光ファイバ技術による高速道路橋の長期モニタリングに関してアメリカＦＨＷＡ（連邦道路管理局）橋梁の長期性能検討プロジェクトチームなどと共同研究を推し進めている。（呉教授他）- 66 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター【大学院生の教育】
1) ５名の社会人博士課程入学者をリクルートした 2013 年度につづき、2014 年度には 3 名の社会人博士課程入学者をリクルートした。
（齋藤特命教授）センター教員の連携による指導体制を構築している。
2) 当センター所属院生を中心にして、茨城大学学生国際会議（１１月１５日１６日：水戸キャンパス）の企画・運営を行った。（呉教授、沼尾教授、鎌田教授、湊教授、桑原准教授、外岡准教授）
3) 羽渕研究室学部 4 年生 高柳翔太君の研究成果発表「ＬＥＤのオンオフ信号による光ワイ
ヤレス通信の研究成果」が電子情報通信学会東京支部学生会学生奨励賞を受賞した。
（全
発表数数：２２９、受賞者数：２１）4) 羽渕研究室博士前期課程 2 年生 ライ サチン君の国際会議発表「Proposal of TurboCoded Differential OOK for Optical IM/DD System」が RISP International Workshop
on Nonlinear Circuits, Communications and Signal Processing (NCSP'15)にてStudent Paper Award を受賞した。

2. 実績一覧【学術誌論文】
1） 野口宏, 大瀧保広, 鎌田賢: BCP としての学内データセンターの設置とその活用方針, 学術
情報処理研究, 18, 24－32 (Sep. 2014).
2） 須藤翔太, 小玉駿, 福田貴大, 渋沢進, 鎌田賢, 米倉達広, 歩行者の位置に応じて情報を正対表示するシステム, 電子情報通信学会論文誌(A), Vol.J98-A, No.1, pp.129-134, Jan.
2015.
3） コンクリートのひび割れ進展計測のための画像解析手法に関する基礎的研究，車谷麻緒，松浦遵，根本忍，呉智深，土木学会論文集 A2（応用力 学），印刷中．
4） 異形鉄筋周辺のコンクリートに形成する内部ひび割れモードの再現シミュレーション，車谷麻緒，根本優輝，岡崎慎一郎，日本計算工学会論文 集，Vol.2014,pp.20140008, 2014.
5） 微細ひび割れの形成と接触を考慮した準脆性材料の圧縮破壊シミュレーション，神野真弥，
車 谷 麻 緒 ，寺 田 賢 二 郎 ，京 谷 孝 史 ，樫 山 和 男 ， 日 本 計 算 工 学 会 論 文 集 ，Vol.2014,
pp.20140006, 2014.

- 67 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

6） Kyohei Sumikawa and Hiromasa Habuchi : Influence of Scintillation and Background Noise on
LDGM-BPPM with Unequal Transmission Power Allocation Scheme in Optical WirelessChannel, Journal of Signal Processing, Vol.18, No.4, pp.181-184 (2014)
7） Yusuke Takamaru, Sachin Rai and Hiromasa Habuchi :Theoretical Analysis of New PN Codeon Optical Wireless Code-Shift-Keying, IEICE Transaction on Fundamentals, Vol.E97-A,
No.12, pp.2572-2578, (2014-12)8） Kyohei Sumikawa and Hiromasa Habuchi : Optical Wireless LDGM-BPPM With Unequal
Transmission Power Allocation Scheme, IEICE Transaction on Fundamentals, Vol.E97-A,
No.12, pp.2579-2585, (2014-12)9） An Arafa M. A. Ibrahim, Zhishen Wu, Mohamed F. M. Fahmy, and Doaa Kamal: Experimental
Study on the Structural Performance of Concrete Bridge Columns Reinforced by Hybrid Steeland FRP Reinforcements. Composites for Construction, ASCE Journal. (submitted)10） Arafa M. A. Ibrahim, Mohamed F. M. Fahmy and Zhishen Wu: Bond-Based Study on Hybrid
FRP and Steel Bars as Main Reinforcement for Bridge Columns. Journal of Composite
Structures. (submitted)11） Huang Huang, Zhishen Wu and Ryota Tagayanegi: Fiber model-based identifications for
flexural behavior of reinforced concrete columns with self-sensing basalt-fiber-reinforced
polymer bars. Smart Materials and Structures. (submitted)
12） H. Huang, Z.S. Wu and K. Kishida: Wavelet-based signal processing of high-sampling-ratestrain measurements of BOTDA-based distributed fiber-optic sensing. Optical Fiber
Technology. (submitted)【招待講演】
1） Zhishen Wu: Advancement of Fibre Optic sensing technology for health monitoring of civil
structures. The Cambridge Conference on Fibre Optic Sensing in Civil Infrastructure, 30 June
– 1 July 2014, Robinson College, University of Cambridge
2） Masaru Kamada: Cardinal splines in piecewise constant tension, 5th International Conference- 68 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

on Computational Harmonic Analysis, Vanderbilt University, Nashville, May 22, 2014.

【学会発表等(国内,国際)】
1) 宮坂隆平, 武田茂樹, 鹿子嶋憲一, 梅比良正弘, " UHF 帯 RFID による災害時電子掲示板
への情報伝達に関する検討," 電気学会東京支部茨城支所研究発表会, A13,pp.24-25,
Nov. 2014.
2) Effect of internal cracking on mass transfer resistance of cover concrete, Okazaki,S., kurumatani, M., Ujike, I. and Takamoto, N.,Proceedings of Concrete Solutions,
5th International Conference on Concrete Repair, pp.683-690, 2014.
3) Toshiya Watanabe, Naohiro Ohtsuka, Susumu Shibusawa, Masaru Kamada, Tatsuhiro
Yonekura, Design of lower limb chair exercise support system with depth sensor,
The 11th IEEE International Conference on Ubiquitous Intelligence and Computing(UIC 2014), pp.104-111, Dec. 2014, Indonesia.
4) Toshiya Watanabe, Naohiro Ohtsuka, Susumu Shibusawa, Masaru Kamada, Tatsuhiro
Yonekura, Motion detection and evaluation of chair exercise support system withdepth image sensor, International Workshop on Future Trends in Computing System
Technologies and Applications (FUSION 2014), pp.800-807, Dec. 2014, Indonesia.
5) 鎌田和樹, 渋沢進, 深度画像センサを用いた拮抗体操支援システム, 電子情報通信学会
福祉情報工学研究会, Vol.114, No.357, WIT2014-66, pp.75-80, Dec. 2014, 東京.
6) 中屋隆, 澁澤進, Kinect センサを用いた嚥下体操支援システム, 情報処理学会第 162 回
ヒューマンコンピュータインタラクション研究会, March 2015, 東京.
7) Yuki Takahashi, Michitoshi Niibori and Masaru Kamada: NeighborNote: An Evernote
application with capability of suggesting related notes based on user operation
history, Proceedings of the 17th International Conference on Network-BasedInformation Systems(NBiS 2014), Salerno, Italy, 331-335 (Sep. 2014).

- 69 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

8) Yuto Yoshida, Michitoshi Niibori and Masaru Kamada: A business Log system to display
related logs based on past cyclic events of business, Fifth International Workshop
on Heterogeneous Networking Environments and Technologies (HETNET 2014),
Proceedings of the 17th International Conference on Network-Based Information
Systems(NBiS 2014), Salerno, Italy, 545-548 (Sep. 2014).
9) Erjing Zhou, Michitoshi Niibori, Shusuke Okamoto, Masaru Kamada and Tatsuhiro
Yonekura: Interactive animation authoring platform based on state-transition
diagrams that runs on Android devices, Third International Workshop on Web Service
and Social Media (WSSSM 2014), Proceedings of the 17th International Conference
on Network-Based Information Systems (NBiS 2014), Salerno, Italy, 596-599 (Sep.
2014).
10) Satoshi Kozawa, Michitoshi Niibori, Yasuhiro Ohtaki and Masaru Kamada:Filemanager that shows off notes out of the files, Third International Workshop on Web
Service and Social Media (WSSSM 2014), Proceedings of the 17th International
Conference on Network-Based Information Systems (NBiS 2014), Salerno, Italy,
611-614 (Sep. 2014).
11) Toshiya Watanabe, Naohiro Ohtsuka, Susumu Shibusawa, Masaru Kamada and Tatsuhiro
Yonekura: Design of lower limb chair exercise support system with depth sensor,
The 11th IEEE International Conference on Ubiquitous Intelligence and Computing(UIC 2014), Bali, Indonesia, pp.104-111, December 2014.
12) Toshiya Watanabe, Naohiro Ohtsuka, Susumu Shibusawa, Masaru Kamada and Tatsuhiro
Yonekura: Motion detection and evaluation of chair exercise support system withdepth image sensor, The International Workshop on Future Trends in Computing System
Technologies and Applications (FUSION 2014), Bali, Indonesia, pp.800-807, December
2014.
13) Sachin Rai and Hiromasa Habuchi: Enhancement of Punctured Turbo Code with UTPA
in Optical Wireless Channel, Proceeding of International Symposium on Information
Theory and Its Applications (ISITA2014), Melbourne, Australia, Session:M-3-C(Coding Theory \& Practice I), pp. (2014-10-27)- 70 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

14) Takuya Eto, Hiromasa Habuchi, and Koichiro Hashiura :Spread Spectrum/Binary

Countdown Scheme with GMPSC for Multi-Hop Wireless Network, Proceeding of EighthInternational Conference on Mobile Computing and Ubiquitous Networking (ICMU2015),
Hakodate, Session:S2: Cognitive Radios and Ad Hoc Networks, (2015-1-20)
15) Sachin Rai, Yusuke Kozawa, Hiromasa Habuchi and Yuto Matsuda : Proposal of
Turbo-Coded Differential OOK for Optical IM/DD System, Proceeding of 2015 RISPInternational Workshop on Nonlinear Circuits, Communications and Signal Processing,
Kuala Lumpur, Malaysia, Session:Optical Communications, 28AM2-4-2, (2015-02-28)
16) 小澤佑介, 羽渕裕真, 楳田洋太郎 :マルチパルス PPM 方式を用いた光無線階層化変調
法の性能解析, 電子情報通信学会ワイドバンド研究会, 名古屋工大, WBS2014-6,
pp.31-36, 2014-05-16
17) 羽渕裕真, 山形正哉 :変形擬 3 進 M 系列による M-ary 陪直交変調の同期追跡法, 電子
情報通信学会ワイドバンド研究会, 名古屋工大, WBS2014-7, pp.31-41, 2014-05-16
18) 江藤拓也, 羽渕裕真, 橋浦康一郎 :拡張プライム符号を用いる 2 進カウントダウン法の提案, 電子情報通信学会ワイドバンド研究会, 大阪市立大学文化交流センター,
WBS2014-13(MICT2014-27), pp.23-27, 2014-07-29
19) 松田優人, 羽渕裕真, 小澤佑介 :同期信号を埋め込んだ差動符号化光 OOK の提案, 電子情報通信学会ワイドバンド研究会, 大阪市立大学文化交流センター, WBS2014-14(MICT2014-28), pp.29-32, 2014-07-29
20) ライサチン, 羽渕裕真 : 光ワイヤレス通信における非均一電力割当型ターボ符号の誤り率特性, 電子情報通信学会ワイドバンド研究会, 大阪市立大学文化交流センター,
WBS2014-20(MICT2014-34), pp.63-66, 2014-07-29
21) 村田直也, 小澤佑介, 楳田洋太郎, 羽渕裕真 :一般化拡張プライム符号系列を用いた双方向可視光通信 LED-to-LED 方式に関するー検討, 電子情報通信学会ワイドバンド研究会, 大阪市立大学文化交流センター, WBS2014-21(MICT2014-35), pp.67-72, 2014-07-29
22) 江藤拓也, 羽渕裕真, 橋浦康一郎 :スペクトル拡散型 2 進カウントダウン法のスルー
プットの一検討, 電子情報通信学会ワイドバンド研究会, 秋田県立大学カレッジプラザ,
WBS2014-35, pp.19-22, 2014-10-03- 71 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

23) 高橋貴大, 羽渕裕真, 小澤佑介: 光 MPPM-CNK のフレーム同期法の一検討, 電子情報通信学会ワイドバンド研究会, 秋田県立大学カレッジプラザ, WBS2014-37, pp.29-32,
2014-10-03
24) 高橋良介, 小澤佑介, 楳田洋太郎, 羽渕裕真 : 照明用 LED による階層型 MPPM-SIK 方式の屋内位置に応じた誤り率特性の評価, 電子情報通信学会ワイドバンド研究会, 熊本大学, WBS2014-41, pp.13-18, 2014-12-1825) 小磯翔, 羽渕裕真 : 誤り訂正符号を組み込んだ秘密分散法の検討, 電子情報通信学会
東京支部学生研究発表会, 明治大, 24, 2015-02-28
26) 高柳翔太, 羽渕裕真, 高丸祐典 : 変形擬 3 進 M 系列を用いる光コードシフトキーイン
グの提案, 電子情報通信学会東京支部学生研究発表会, 明治大, 30, 2015-02-28
27) 細川勇気, 羽渕裕真 : 変形擬 3 進 M 系列対を用いる OFCDM の提案, 電子情報通信学会
東京支部学生研究発表会, 明治大, 36, 2015-02-28
28) 松田優人, 羽渕裕真, 小澤佑介:差動符号化を用いる光無線 OOK の同期保持時間, 電子
情報通信学会総合大会, A-5-5, 立命館大学, 2015-03-10(発表予定)【採択された外部資金及び科学研究費補助金】
1） 科研費 挑戦的萌芽研究 （研究課題番号：26630215）
課題名

地盤中の水の挙動の調査を格段に進展できるワイヤレスマルチセンサの開発

への挑戦
代表 風間基樹（東北大学） 分担 安原一哉, 鎌田賢（茨城大学）
研究期間 2014 年 4 月 1 日～2017 年 3 月 31 日
研究費総額 4,915,000 円
2） 科研費 基盤研究（C） （研究課題番号：26420409）
課題名 可変張力つき 2 変数スプラインの導出とその画像補間への応用
代表 鎌田賢（茨城大学）
研究期間 2014 年 4 月 1 日～2017 年 3 月 31 日
研究費総額 1,700,000 円- 72 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

3） モバイル端末による測位方法の検証に関する共同研究
期間 2013/11-2014/04
金額 250,000 円
4） 科研費 基盤研究(C)課題名 センサネットワークと知識ベースを用いた高齢者見守リシステムの研究代表 澁澤 進，H26 年度澁澤分 550 千円
研究期間 2012 年 4 月 1 日～2014 年 3 月 31 日
研究費総額 4,800,000 円
5)

科研費 基盤研究(C)課題名 ITS のための光／電波融合型通信の高度化
代表 羽渕裕真，H26 年度 1100 千円
研究期間 2012 年 4 月 1 日～2015 年 3 月 31 日 研究費総額 4,200,000 円

6)

寄付金
帝人株式会社
課題名 高機能繊維材料の社会インフラにおける活用拡大、実用化に関する研究
代表 呉智深，H26 年度 500 千円

7)

寄付金
株式会社ＫＳＫ
課題名 「中小企業・小規模事業者ものづくり・商業・サービス革新事業（専門家指導）
代表 呉智深，H26 年度 1000 千円

8)

寄付金
特定非営利活動法人 光防災センシング振興協会課題名 河川堤防の変状検知等モニタリングシステムの技術研究開発（国交省プロジェ
クト）
代表 呉智深，Ｈ２６年から５年間【地域社会活動】
1) 齋藤 修：ひたちなか市外野小学校等における理科教育の支援の一環として、理科・環- 73 -

茨城大学重点研究プロジェクト「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
防災セキュリティ技術教育研究センター

境・情報等の総合的教育を行った（2014 年 11 月〜2015 年 2 月）。
2) 鎌田 賢：第 38 回全国高等学校総合文化祭「いばらき総文祭 2014」コンピュータ部門のプログラミングコンテストにおいて、予選・本選（平成 26 年 7 月 28 日（月）29 日（火））の審査委員を務めた。本選ではデモ展示も行った。

茨城大学工学部附属防災セキュリティ技術教育研究センター(2014 年度)

呉智深（工学部都市システム工学科・教授・センター長）

齋藤修（防災セキュリティ教育研究センター・特命教授・副センター長）

鎌田賢（工学部情報工学科・教授・副センター長）

桑原 祐史（広域水圏環境科学教育研究センター・准教授・センター幹事）

沼尾 達弥（工学部都市システム工学科・教授）

今井（工学部電気電子工学科・教授）

洋

原田 隆郎

（工学部都市システム工学科・准教授）

横田 浩久（工学部電気電子工学科・准教授）

湊（理工学研究科・教授）

淳

武田 茂樹

（工学部メディア通信工学科・教授）

澁澤進（工学部情報工学科・教授）

羽渕 裕真（工学部情報工学科・教授）

外岡 秀行（工学部情報工学科・准教授）

車谷 麻緒（工学部都市システム工学科・准教授）- 74 -

茨城大学重点研究「知的で持続可能な社会基盤および防災セキュリティ技術研究創出事業」
茨城大学工学部附属防災セキュリティ技術教育研究センター
２０１４年度報告書
発行日

平成 27 年 4 月

発行者

茨城大学 工学部 都市システム工学科
教授 呉 智深〒316-8511 日立市中成沢町 4-12-1
Tel: 0294-38-5179 Fax: 0294-38-5268※禁無断転載茨城大学重点研究
http://www.ibaraki.ac.jp/generalinfo/activity/researching/juuten/

茨城大学工学部附属教育研究センター
http://www.eng.ibaraki.ac.jp/research/centers/index.html

防災セキュリティ技術教育研究センター
http://www.eng.ibaraki.ac.jp/research/centers/disaster/index.html