Journal of Civil Engineering and Architecture 13 (2019) 562-571
doi: 10.17265/1934-7359/2019.09.003

D
DAVID

PUBLISHING

Shear Performance of FRCC Beam-Column Joints Using
Various Polymer Fibers
Yu Mu, Akira Yasojima and Toshiyuki Kanakubo
Department of Engineering Mechanics and Energy, University of Tsukuba, Tsukuba-City, Ibaraki 305-8573, Japan
Abstract: Brittle shear failure should be avoided in beam-column joint of a reinforced concrete (RC) frame during the earthquake.
Fiber-reinforced cementitious composite (FRCC) which presents a remarkable deformability especially under tensile and bending
load with a large energy absorption capacity is expected to be used in the crucial part of a RC frame. With the development ofpolymer material, various synthetic fibers have become the best selection to improve concrete capacity and failure resistance without
the corrosion of fibers. The objective of this study is to investigate the influence of fiber bridging effect on the shear capacity of
FRCC beam-column joint. The main parameter of the test in the present study is the fiber types: aramid, polypropylene (PP) andpolyvinyl alcohol (PVA) fiber. To evaluate shear capacity quantitatively, a new calculation method using FRCC tensile
characteristics confirmed by the uniaxial tension test is newly proposed. The difference of below 7% between calculated value andexperimental value demonstrates that the calculation method is feasible.
Key words: Shear, uniaxial tension test, aramid, PP, PVA.

1. Introduction
Beam-column joint is the crucial part of areinforced concrete (RC) frame, which is to ensure theductility of the whole structure especially when theframe is subjected to huge earthquake. Under seismic
response, major damage should be avoided in the
beam-column joint. Even the beam and column step
into inelastic state, the joint has to remain the ability
to transfer actions. The reasons to avoid large damage
in beam-column joint under seismic response are tokeep transferring capacity of the gravity load in thepanel zone, to accomplish large ductility and energy
dissipation by other elements such as beam, anddifficulty of repairing the joint after earthquake [1].
Shear failure in the panel zone causes a typicalbrittle damage in beam-column joint, so its shear
capacity should be given gratifyingly. Shear capacityof beam-column joint is mainly supplied by thedimensions of the panel zone and concrete strength.
An adequate amount of lateral confining
Corresponding author: Yu Mu, Ph.D. candidate, research
fields: concrete structures, fiber-reinforced cementitious
composites.

reinforcement in the panel zone also provides
non-shear failure. In general, however, the dimensionsof the panel zone are limited by the dimensions ofconnecting columns and beams. In addition,
increasing confining reinforcements will cause great
construction difficulties in reinforcement cage andcasting.
Using fiber-reinforced concrete into panel zone ofbeam-column joint to increase shear capacity is not a
new attempt [2-12]. By the introduction of steel fibers
in beam-column joints, steel fiber-reinforced concrete(SFRC) is an attractive alternative to inhibit thedamage of joint panel and increase maximum load.
However, decreased stress caused by steel fiber
corrosion [13, 14] is a severe problem that has to be
faced. With the development of polymer material,
various synthetic fibers have become the best
selection to improve concrete capacity and failure
resistance without the corrosion of fibers [15, 16].
A newly cementitious-composite-based material
named fiber-reinforced cementitious composite(FRCC) is cement composite with the mixture of shortfibers to increase ductility of cement composite.

Shear Performance of FRCC Beam-Column Joints Using Various Polymer Fibers

Comparing to the conventional concrete, FRCC has aremarkable deformability especially under tensile andbending load with a large energy absorption capacity
due to the fiber bridging effect. After first cracking,fiber can transfer tensile force through crack whichstrongly affects the tensile performance of FRCC [17].
This remarkable bridging capacity makes it anappropriate choice for application in beam-column
joint of RC structures to resist inelastic deformation.
Until now, FRCCs can be constituted with a categoryof fibers, such as carbon [18], steel [19] and polymer
fibers [20]. Whereas, most research in materials fieldhas been focused on FRCC with a high modulus
polyethylene (PE) fiber, and has been conducted bybending and tensile test [21]. Structural performanceof beam-column joints using polyvinyl alcohol (PVA)[22, 23] and steel fiber [24] in panel zone with a fiber
volume fraction of 1% has been confirmed. Fibers canrestrain expansion of crack width, increase shear
capacity and improve structural performance rather
than the specimen without fiber. The previous
research [25] has also revealed that PP-ECC (a sort ofpolypropylene
fiber-reinforced
cementitious
composite) can serve as transverse reinforcements tocarry the applied load.
Precast construction method which is widely usedin RC buildings especially in high skyscraper in Japan
becomes more and more popular by ensuring better
quality, simplified install procedure and shorter
duration. Until now, a new precast system which casts
the joint panel combining with beam and separatingcolumn into two parts has been proposed. Even
though the FRCC constructability is tough, byadopting this precast method, FRCCs can be used inpractical engineering easily. Therefore, it is a smart
way of enabling FRCC to play a better role in a
Table 1563

beam-column joint.
In this research, various polymer fibers have beenutilized in the FRCCs beam-column joint to increase
shear capacity and reduce the damage of the panelzone. Compared with steel fiber, polymer fibers havea better durability in cement matrix. The loading testof FRCCs beam-column joints with a fiber volume
fraction of 1% is conducted to make clear the
influence of fiber type on shear capacity of panel zone.
Tensile performance of FRCCs characterized fromuniaxial tension test is also discussed. A new
calculation method for evaluating shear capacity of
FRCCs beam-column joint is proposed based on thestandard of Architectural Institute of Japan (AIJ) [26].

2. Outline of Test
2.1 Material Properties
The target compressive strength of the FRCCs was
set to 50 MPa. As listed in Table 1, water-cement ratioof 0.56 was adopted, which is based on the previous
study [17], fiber volume fraction for each specimen
was 1%. The mechanical properties of each polymer
fiber are shown in Table 2 and Fig. 1. Aramid fiberand PP fiber are fibrillated with a same length of 30
mm, while 12 mm for PVA fiber. Diameter for aramid,
PP and PVA is 0.5 mm, 0.7 mm and 0.1 mm
independently. Aramid fibers having an extraordinary
tensile strength of 3,432 MPa have been used inaircraft, military vehicles, bullet proof vests and manyothers. The used aramid was stranded from single
fibers. Surface roughness embossing has been madeon the PP fiber to improve the bond property.
2.2 Test Specimens
Two specimens (No. 30 and No. 31) were designed

Mixture proportion of FRCC.

Unit weight (kg/m3)
Water
CementFly ash
Sand
1.0
0.39
0.50
380
678
291
484
Cement is high-early-strength Portland cement; fly ash is Type II of Japanese Industrial Standard (JIS A 6202); sand is size under
0.2 mm; high-range water-reducing admixture is binder × 0.6%.
Fiber volume fraction (%)

Water-binder ratio

Sand-binder ratio

564
Table 2

Shear Performance of FRCC Beam-Column Joints Using Various Polymer Fibers
Mechanical properties of fiber.

ID

Fiber

No. 30No. 31
No. 32†

AramidPP
PVA†

Length
(mm)
30
30
12

Diameter
(mm)
0.5
0.7
0.1

Tensile strength
(MPa)
3,432
580
1,200

Elastic modulus
(GPa)
73
4.6
28

Specimen No. 32 is from the previous study [23].

Fig. 1

Aramid fiber and PP fiber used in this study.

to fail by shear in panel zone before flexural yielding
to evaluate the shear performance of joint panel.
FRCCs were only used in the panel zone. Dimensionsof the FRCC beam-column joints are shown in Fig. 2
and Table 3. The column section was 500 mm × 500
mm and the beam section was 380 mm wide and 420
mm deep. The span of beam and column was 2,700mm and 1,560 mm which is considered as a half scaleof real RC structure. High strength rebars wereadopted for main reinforcing bars in beam and column
to insure the priority of shear failure in panel zone. To
grasp the fiber influence on the shear performance of
panel zone, no hoop was used in panel zone.
In order to compare FRCC beam-column joints
shear performance better, specimens from previous
studies [22, 23] are also listed in this study. The
authors have reported the experimental results of No.
24 (without fiber) and No. 32 which is the specimen
having 1% PVA fiber in panel zone. All otherparameters are same as this research.
2.3 Loading Method and Measurement
The reversed cyclic loading is applied to the beams
by controlling story drift angles from R = ±1/400 to±1/20 rad. Story drift angle was controlled by theactuators attached to the inflection points of beams,
which is shown in Fig. 3. Oil jacks were used on theinflection points to support the columns. The

measurements were the applied load on beams, story
drift angle, deformations of beam and column. Setupsof linear variable displacement transducers (LVDTs)
are shown in Figs. 4 and 5.

3. Test Results
3.1 Failure Modes
Crack patterns of all specimens observed at
maximum load are shown in Fig. 6. Except for No. 30,
maximum loads of all specimens were observed at thestory drift angle R = 1/50 rad. Since aramid fiber has ahigher fiber bridging effect, maximum load of No. 30
was observed at the story drift angle R = 1/33 rad. For
all specimens, shear crack occurred on panel zone first,
and then flexural crack and shear crack on beam wereobserved in this order. Diagonal shear crack on panelzone developed more and more visibly due to crack
opening and closing under the increased cyclic load.
Large number of diagonal cracks appeared on thesurface of panel zone during loading which leads tothe shear failure. In comparison with No. 24, thecracks of all specimens with fibers have been
inhibited due to the effect of fiber bridging. Aftermaximum load, the cracks of specimens with fibers
developed wider and deeper however if compared toNo. 24, the change was not obvious. By using fibers
into beam-column joint, the damage of panel zone canbe improved.

Shear Performance of FRCC Beam-Column Joints Using Various Polymer Fibers

565

FRCC

Fig. 2
Table 3Specimen dimensions.
Specimens list.

Panel
Beam
Parameter
Reinforcing bar
Stirrup*No. 24
Without fiber
No. 30
Aramid18-D22 (USD685)
6-D10@60 (SD785)
No. 31
PP
No. 32†
PVA*
Specimen No. 24 is from the previous study [22].
†Specimen No. 32 is from the previous study [23].
ID

Fig. 3

Loading method.

Reinforcing bar
16-D22 (USD685)

ColumnHoop
6-D10@60 (SD785)

566

Shear Performance of FRCC Beam-Column Joints Using Various Polymer Fibers
Pin

570

LVDT
Minus

Minus

Plus

570

420

Plus

LVDT

Roller（Linear Bush）
1100

Fig. 4500

1100

Measurement of story drift angle.

Minus

Plus

Plus

Minus

645

270

645

LVDT

Jigs fixed
points

LVDT
1190

Fig. 5

Measurement of local deformation.

320

1190

Shear Performance of FRCC Beam-Column Joints Using Various Polymer Fibers

Fig. 6

No. 24 (no fiber)*
No. 30 (aramid)
Crack patterns at maximum load.

3.2 Load-Story Drift Angle Curve
Fig. 7 shows the relationships of load and story drift
angle obtained from the cyclic loading test. The peakloads are listed in Table 4. Specimen No. 30 has thehighest value of 544 kN, which was mainly attributedby its higher fiber bridging effect. Since all the
specimens were designed by failure of panel zone,
peak loads of specimens with fibers were increased
significantly compared to No. 24 due to theeffectiveness of fiber bridging.

4. Evaluation of Shear Capacity
4.1 Outline of Tension Test
To grasp the tensile characteristics of FRCC, theuniaxial tension test was conducted. Aramid fiber, PP
fiber and PVA fiber were used to test the tensile
property. The fibers used for the tension test are thesame as those used in the beam-column joint
experiment. The mixture proportion of mortar matrix
has already been presented in Table 1. The fiber
volume fraction is 1%.
The details of the specimen and the loading method
are shown in Fig. 8. The total length of the specimen
is 510 mm with carbon fiber sheets attached at bothends to avoid peel-off of the steel plate. Since theincreasing external moment caused by setup
irregularity and local fracture caused by secondary
moment will be an inevitable factor to the experiment,
pin-fix ends were applied at the boundaries tominimize possible effects to the results. As shown in
Fig. 9, a notch was being made in the middle of thespecimen. The sectional area at ligament is 40 mm ×
40 mm. Tensile load and deformation in the test

No. 31 (PP)567

No. 32 (PVA)†

region were obtained directly from the experiment.
The crack width is the average value of two pi-type
LVDTs.
4.2 Results of Tension Test
All specimens fractured at the ligament. Tensilestress is calculated by tensile load divided by sectional
area at the ligament. Fig. 10 shows the example
photographs of the fibers across the crack duringloading. The relationships of tensile stress versus
crack width are shown in Fig. 11. The tensile stressshowed a significant drop after first cracking. Due tothe fiber bridging effect, the tensile stress increased
until to the second peak and then decreased gradually.
The average tensile stresses of Aramid, PP and PVA
specimens at the second peak are 3.31 MPa (crack
width at 0.995 mm), 1.61 MPa (crack width at 1.199mm) and 1.80 MPa (crack width at 0.680 mm),
respectively.
4.3 Evaluation of Shear Capacity
By assuming that the shear stress in the panel zone
is also carried by fiber bridging effect, shear capacityof beam-column joint is evaluated through the tensile
characteristics of FRCC.
It is considered that the strut mechanism in FRCC
beam-column joint keeps until to story drift angle of R
= 1/50 rad due to the bridging effect of fibers which
are across the diagonal crack on the surface of panelzone. After that, diagonal cracks start to move to shear
sliding direction which leads to the maximum load. At
the maximum load, by assuming failure of strut
mechanism and disappearance of fiber bridging effectare occurred simultaneously, calculation method forShear Performance of FRCC Beam-Column Joints Using Various Polymer Fibers

568

500

Load Q (kN)No.24
No fiber-0.06

Load Q (kN)No.30
Aramid 1%

-0.03

0

-500

500

0.03
0.06
-0.06
Story drift angle R (rad)

-0.03

0

-500

-0.03

Qmax=385kN
Qmin=-389kN

0

-500

Load Q (kN)

500

0.03
0.06
Story drift angle R (rad)Qmax=544kN
Qmin=-531kN

Load Q (kN)

No.32
PVA 1%

No.31
PP 1%

-0.06

500

-0.06
0.03
0.06
Story drift angle R (rad)Qmax=495kN
Qmin=-488kN

-0.03

0

-500

0.03
0.06
Story drift angle R (rad)Qmax=461kN
Qmin=-461kN

Fig. 7 Load-story drift angle curve.
Specimen No. 24 is from the previous study [22].
†Specimen No. 32 is from the previous study [23].
*Table 4

Peak load and story drift angle at peak load.

No. 24 (no fiber)
No. 30 (aramid)
No. 31 (PP)No. 32 (PVA)

Peak load
389 kN544 kN495 kN461 kN

shear capacity of FRCC beam-column joint in Eq. (1)can be proposed. Eq. (1) is derived as the summationof the Eq. (2) given by “Design Guidelines for
Earthquake Resistant Reinforced Concrete Buildings
Based on Inelastic Displacement Concept” [26] toshear force carried by FRCC expressed by Eq. (3). As
shown in Fig. 12, shear force is derived from tension
force carried by fibers. The crack angle  is observed
directly from the surface of panel zone. The second
peak load in uniaxial tension test is adopted for
maximum tensile stress in each type of fibers.
Experimental and calculated values of shear

Story drift angle
1/50 rad1/33 rad1/50 rad1/50 radcapacity are converted to the shear force which isapplied to beam. As listed in Table 5, the difference of
below 7% between calculated value and experimental
value demonstrates that the calculation method is
feasible. By adopting this method, shear capacity of
FRCC beam-column joint can be calculated fromuniaxial tension test.
V ju  V jc  V jf

(1)

V jc =     Fj  b j  D j(2)

V jf   t ,max  d b  b j(3)

Shear Performance of FRCC Beam-Column Joints Using Various Polymer Fibers

Fig. 8Tensile test specimen.

Fig. 9Cross section of tensile test specimen.

Ara m id30m m

Fig. 10Fibers across the crack during loading.

PP30m m569

Aramid with notch
Second peak
Avg. 3.02MPa

6
4
2
0

Fig. 110

1
2
3
4
Crack width (mm)58Tensile Stress（MPa）

Tensile Stress（MPa）

8

Tensile Stress（MPa）

Shear Performance of FRCC Beam-Column Joints Using Various Polymer Fibers

570

PP with notch
Second peak
Avg. 1.61MPa

6
4
2
0

0

1
2
3
4
Crack width (mm)58PVA with notch
Second peak
Avg. 1.80MPa

6
4
2
0

0

1
2
3
4
Crack width (mm)5Tensile stress-crack with curve.

Fig. 12 FRCC beam-column joint under shear.
Table 5Experimental value and calculated value.

Experimental value Vexp (kN)Calculated value

Eq. (2) Vjc (kN)
Eq. (3) Vjf (kN)
Eq. (1) Vju (kN)

Vexp/Vju

where, V ju is shear capacity; V jc is shear capacity by
AIJ guideline; V jf is shear capacity carried by fiber;
shape coefficient;  is orthogonal beamcoefficient; Fj is shear strength of panel zone; b j iseffective width; D j is column height;  t ,max is
maximum FRCC tensile stress; d b is effective depth isof beam.

5. Conclusions

Aramid
544
424
83
507
1.07

Acknowledgments
The authors acknowledge Mr. Faizal Hanif, former
student in University of Tsukuba, for his help tocomplete the experiments.

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test using various polymer fibers was conducted. Due
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specimen without fiber. A new proposed calculation
method using FRCC tensile stress obtained fromuniaxial tension test can predict shear capacity of

PVA
461
412
49
461
1.00

FRCC beam-column joint accurately.

To investigate the influence of fiber bridging effecton shear performance of FRCC, beam-column joint

PP
495
426
44
470
1.05

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