QUALITY CONTROL OF RC ELEMENT FOR
EARTHQUAKE DESIGN
Javier Yukio Yamamoto Munoz1
MEE07149

Supervisor:

Dr. Goto Tetsuro2
Dr. Taiki Saito 3

ABSTRACT
Recently the RC structure has been increasing adopted in Dominican Republic; however, quality of thebuildings in the rural area is poor. For this reasons my study is focused on the quality control of thestructural elements to secure a better performance when an earthquake happen. By visiting several
constructions site in Japan, the construction method, technology and the quality controls of their concretework. By means of Comparing them with the methods used in the Dominican Republic and a proposal isprepared to improve the construction process and the quality of the structural elements in my country.
Also studied how the honeycombs affect the concrete strength in the structural elements and a seismic
capacity of high quality RC member. Based on the study result, methodology for better RC elements isproposed in this paper.
INTRODUCTION
A possibility is high that in a relatively near future the Dominican Republic is going to be affected by astrong seismic shock, since the last strong earthquake in 1946, 62 years has already passed. Despite thehigh seismic risk of our territory and despite the proximity of an important seismic event, the country is
not prepared for an earthquake of considerable Magnitude. Since most of the population did notexperience the last great earthquake of the August 4, 1946, the seismic risk in the Dominican Republic
tends to be underestimated. This underestimation of the seismic risk allows construction of building inmost inappropriate zones and quality of the buildings in the rural area is poorer. The informal constructionof houses occupies 80% in all the country, this construction are done by the own owners or by neighborsof the place who do not count on any professional engineering formation. These types of buildings would
be of the first to collapse at the time of an earthquake.
In the morning of September 22, 2003 the north zone of the Dominican Republic was hit by an earthquakeof magnitude 6.5, the epicenter was located 15 kilometer from Puerto Plata city and 20 kilometer from
Santiago de los Caballeros city. This earthquake damaged important buildings in Puerto Plata city,
including schools and hospitals, and some buildings collapsed. After the earthquake, it was found thatquality of these collapsed buildings were poor in terms of constructions materials and constructions works.

1 Engineer, private company in Dominican Republic (EPSA-LABCO S.A.)
2
3Senior Researcher of National Institute for Land and Infrastructure Management (NILIM),
Chief Research Engineer of Building Research Institute (BRI)QUALITY OF RC CONSTRUCTION IN JAPANConstructions PracticeIn the Dominican Republic concrete is most commonly utilized material for the constructions; thestrength depends on several variables like characteristic of the materials, production method, transport,placement and cured. For these reasons part of this paper involves observing the construction process inJapan and exposing the problems of quality control that we have in the Dominican Republic.
Table 1 List of construction site visited in JapanLocation
12
34

Named

DetailMitakadai, TOKYO(UR Mitakadai complex)
Oumigison, OKINAWA prefecture(Oumigison town office)Miyakojima, OKINAWA
prefecture (Irabu-oohashi)

8 story RC apartment building, UnderConstruction.
Reinforce Concrete office building, Constructed in1925, under partial rehabilitation.

Concrete Factory in Miyakojima

RC bridge, Under Construction
Automatic system to manufacture concrete severe
quality control by computer monitoring

Important Factor for Construction QualityFormwork SystemThe formwork is very important when we make out a structural element of reinforced concrete, since thisform the required element. In both Japan and Dominican Republic wooden formwork is used.
The formwork system used in Japan is simpler and has better quality than in Dominican
Republic. The wood used in Japan is processed and prepared to accomplish this function, which is moreresistance and can be used more repeatedly. In order to join the formwork's woods in Japan steel separator
is used to maintain the shape not to open while concrete is casted. In Dominican Republic use wooden lot
is used but, is not resistant as the steel separator.
Manufacture of Concrete
Not all the concrete factories in Dominican Republic have high technology as the concrete factories inJapan, and the majority of these factories wit high technology concentrate in the capital or in major cities
of Dominican Republic. Because in these places the most important projects are implemented and thevolume of the consume concrete is more. In the rural area the concrete is made by the construction
workers without any concrete design.
In Japan the concrete mixing is totally automatic, and the mixture is homogeneous wit all theproduction. In the Dominican Republic it is not guaranteed that concrete mixture, brought to theconstruction site is homogeneous. In many cases delivery concrete is delayed and for these reasons thedriver of the truck adds additional water or additive to the concrete mixture before placing the concrete.
For this reason it is necessary to make the concrete slump test to each concrete truck.
Qualified Staff
At Dominican Republic, the laborers do not have technical trainings and the majorities are Haitian
immigrants, and in many instances they are not aware of what they are doing. For that reason they always
go on with the same procedure of work and are very difficult to learn new techniques. To improve thequality in the construction site, capacitate the staff is important in order to increase quality and make amore fast work.

HONEYCOMB CONCRETE EFFECT TO THE CONCRETE STRENGTH
The specimens of concrete were given load and determine the Shear Stress to with and withouthoneycomb. The concrete strength is 21 N/mm², slump 18 cm and maximum coarse aggregate site is20mm; the specimens were cast on July 2, 2008 and the actual test was carried out on August 5, 2008.
Shear Strength Test
Portable Structural Testing Equipment (PSTE)
Measuring instrument used is Data logger: TDS-303 ｂy Tokyo Sokki, Japan
Transducer: CDP50 by Tokyo Sokki, Japan.

LoadDirection
Transducer

Specimen

Figure 1 (PSTE ) Developed by Dr. Goto Tetsuro of NILIM, Japan.
Specimens
The dimensions of the concrete specimen are 70cms x 70cms with 10cms of thickness. 2 type’s specimens
without honeycomb and with honeycomb concrete were prepared. The variable of this test is thehoneycomb concrete area. Are tree type PH-1, PH-2 and PH-3.

PNH specimen

PH-2 specimen

PH-1 specimen

PH-3 specimen

Figure 2 Specimen of Honeycomb

In order to create the honeycomb, sifter of 20mm is used to select large size aggregates. It results
reduction of the quantity of mortar in the mixture.

Figure 3 Construction Process of specimens
Material test
Table 2 Quality control of concreteCylinder Test

Material
Concrete

Compression
Strength24.62 N/mm²Specimens

TensileStrength
2.15N/mm²

Pulse Velocity
0.38 Km/sec

Compression Test
From the test results, the compressive strength and Young’s Modulus of the concrete are listed in Table 2.
The compressive strength is obtained by using the ratio of damage load fc and section area of the sample,
and the Young’s Modulus is calculated by using the secant value of 0.5*fc. The compressive strength andYoung’s Modulus are about 25MPa and 40kMPa respectively as shown in Table 1
Splitting Test
The splitting test is about 2.15 N/mm² respectively as shown in Table 2.

σt =2Pπdl

σt: Tensile strength
P: Maximum loadd: Diameter of cylinderl: Length of cylinder

PUDINT Test
In order to check the homogeneity of the concrete in non honeycomb concrete area, an Ultrasonic nondestructive integrity testing (PUDINT) are used. This test is applied to all Concrete plate but not in theconcrete honeycomb concrete area.
As velocities, showing in the Table 2, do not have drastic change in the tested areas. That means
the concrete preserve the uniformity in all the concrete area except for the honeycomb area.
Shear Test Results
Figure 4 shows the relationship between vertical deformation and load obtained from shear stress test for 4specimens.

Load vs Vertical Deformation
400350

Load (KN)

300
250
200
PNH
PH-1

150
100

PH-2
PH-3

50
000.2

0.4

0.6

0.8

1

Vertical Deformation (mm)Figure 4Table 3 result of shear stress test
Specimen
PNH

Load(KN)
379.5

Qu(KN)
268.35PH-1

238.37168.55PH-2

259

183.14PH-3

226.75160.34Area(mm²)
70000

ShearVerticalStrength Deformation(N/mm²)(mm)3.83
0.03
2.41

0.18

2.62

0.39

2.29

0.79

From figure 4 it is observed that vertical deformation of specimen with honeycomb become large
compared with specimen without honeycomb. The specimen whit large honeycomb area, PH-3, gives thelargest vertical deformation.
Figure 5 shows the graph of shear strength of the specimens.
From this graph, the ratios of shear force reduction are 1.43 for PH-1, 1.21 for PH-2 and 1.54 for PH-3 inaverage, the honeycomb reduce 36.4%.

Figure 5

When comparing the results between them with honeycomb specimen and without honeycombspecimen. The load capacity of PNH is higher than the PH-1, PH2 and PH-3. The Vertical Deformation of
the PH-1, PH2 and PH-3 specimen is proportional to the honeycomb area.
The honeycomb affected the concrete the shear strength of de concrete and de verticaldeformation of the specimens
CONCLUSION
From this study, it is conclude the honeycombs in the structural element affect the strength of the concrete.
The honeycomb area is an important factor in this aspect. However, it is ideal to test specimens ofstructural elements with steel bars as adopted in the actual structural body. Therefore, the challenge for thefuture would be testing structural elements with the same honeycomb to examine the effects ofhoneycomb to the structural elements. Also step from this study is to verify the repair methods used forhoneycomb, and conventional repair methods should be tested to verify their effectiveness. In this study
specimens used are not structural elements. When comparing the construction methods of the Dominican
Republic with those of Japan, the problems at the construction site in the Dominican Republic are clearlyobserved as follows.
o Absence of quality control
o Ignorance of regulation for quality control.
o Expansion of buildings often made ignoring original structural design.
o Absence of qualified staff.
These problems can be minimized with proposals of quality control on the construction site. The
proposal includes training and education to the construction workers in term of quality control.
Following recommendations are presented:
o Educate the workers, designers and constructors in fulfilling the standards established by theconstruction code.
o The government has to introduce programs capacitating the workers.
o Investing to new technologies, which help to secure the concrete quality such as assembling theformwork.
ACKNOWLEDGEMENT
I would like to express my sincere gratitude to Organization of Urban Renaissance Agency (UR), The
Morimoto Construction Company, the Oomigi Town Office of Okinawa prefecture government,
Miyakojima Branch Office of Okinawa prefecture government, National Registered Architect Associationof Miyakojima Branch of Okinawa prefecture and Daiyomi Construction Company.
REFERENCE
Ing. Héctor E. O’Reilly Pérez, Reglamento Sísmico Dominicano, BOLETIN DE LA SOCIEDAD
DOMINICANA DE SISMOLOGIA E INGENIERIA SISMICA (SODOSISMICA)
Ramón A. Delanoy, Aspectos de Sismología Dominicana, 1995
R. Osiris de León, RIESGO SÍSMICO EN LA REPUBLICA DOMINICANATadashi Maki, SENIOR VOLUNTEER, JICA ADVISER (ABTI-EARTHQUEAKE) ,SEISMICITY in theDominican Republic- For Measurement of Anti- Earthquake-2004.