SIESMIC EVALUATION AND REHABILITATION OF
RC STRUCTURE IN DOMINICAN REPUBLIC
Yesica Hypatia Perez Alejandro*
MEE12612

Supervisor: Mizuo INUKAI**ABSTRACT
The Dominican Republic is a country with high seismicity that has been affected by earthquake foryears. It has been highly vulnerable to earthquakes because of population growth, changes indemography and economic patterns, and other changes in social dynamics. These factors have led touncontrolled settlements in disaster-prone areas, and the most devastated area is the northern coast
because the area has more active faults than other areas. Since most of the existing structures in thecountry do not comply with the seismic standards or they were designed before the first seismic code,
the seismic evaluation and the building rehabilitation of reinforced concrete are important. Therefore
the seismic assessment is a way to reduce the risks in case of earthquakes.
Keywords: Seismic code, Seismic Evaluation, Rehabilitation, Stera 3D.

1. INTRODUCTION
The Dominican Republic is located in the eastern part of Españiola Island in the Caribbean Sea, and itis the second largest island of the Greater Antilles. It occupies a total land of 48,730 km². Its
geography is varied; the seismic tectonic framework covers a wide area on its surface and many
epicenters are located around the Dominican Republic. A present study shows that earthquakes
occurred in the country were produced by the faults which are considered to have been not active at
this time. Due to many previous factors the towns are vulnerable, and it is required to assess theseismic performance for existing structures to determine their decisive weakness ties to seismic
demand established by the seismic code. In addition, reinforced concrete structure is one of the mostcommon types in cities; therefore there is a necessity to study their seismic vulnerability. In addition,buildings designed and built without earthquake resistant guidelines should not be overlooked andneed careful consideration for the proper performance during the occurrence of earthquakes.

2. PURPOSE AND SCOPE
The purpose of this study is to describe the behavior of existing reinforced concrete buildings by theevaluation using standard methods to determine design seismic vulnerability of structures in order toadapt various structural rehabilitation methods which are conducted in Japan, to the Dominican
Republic.
The scope is to evaluate all the existing structures designed without any seismic codes, andreview ability of the structure to withstand moderate and strong earthquakes as much as possible,
using vulnerability studies to determine the ability of structures. As many buildings are characterized
by deficiencies of the joints, the columns do not have enough shear strength against earthquakes.
*

Unit of Evaluation of Seismic Vulnerability of Infrastructure, Building and Housing, National Geological
Survey (SGN), Dominican Republic**International Institute of Seismology and Earthquake Engineering, Building Research Institute, Japan.

13.

METHODOLOGY

The evaluation used in this study is determined by means ofdifferent conditions of the structure, which organizes a quantitative
process that allows us to estimate the seismic vulnerability ofbuildings using equations and the method of evaluation. The
parameters can give the conditions and the degree of vulnerability
based on the most relevant feature of the used model.
Chronological process used for this case is shown in Figure 1.
Figure 1. Flow chart of methodology.

4. STRUCTURAL EVALUATION GUIDE IN JAPANThe standard for the seismic evaluation of existing reinforced concrete buildings in Japan is conductedby guideline assessment which has three levels of evaluation area, and for this study we apply only thefirst and second levels. The seismic performance of buildings is characterized by seismic index ofstructure (Is) as shown in Eq. (1) and the seismic safety of the buildings shall be judged based on thestandard for judgment on seismic safety (Is₀) as show in Eq. (2).

I s = E0 ⋅ S D ⋅ T(1)Is 0 = E s ⋅ Z ⋅ G ⋅ U(2)Where:

E0 : Basic seismic index of structure, S D : Irregularity index, T : Times index
E S : Seismic demand index of structure, Z : Zone index, G : Ground index, U : Usage index
The hospital has a main building as shown in Figure 2, and it has the following conditions: the space ofthe reinforcement bars is considered to be 300 mm in vertical and horizontal direction, and the diametersof reinforced bars 9.50 mm and 12.7mm. The number of layer of the reinforcement is double; the yieldstrength of the steel is 420 N/mm². The thicknesses of wall on the first and second floors are 250mm,
and the third floor is 200 mm and the fourth floor is 150mm. Compressive strength of the concrete is 28
N/mm².

Figure 2. Main building of hospital.

2

4.1 WRC First level screening procedure
The first screening procedure is calculated by seismic index of structure in each direction of thelongitudinal and the transverse of the structure.
The seismic index of structure is calculated by Eq. (1). In this method, the evaluation
results are different; because the transverse axial force of the walls is considered, it is necessary torealize rehabilitation in the first and second floors in transverse (Y) direction as shown in Table 1,
because the building does not comply with the requirements for establishment or basic seismic index
demand (Is₀).
Table 1. Seismic index Is of structure.
Direction floor ∑(twj*Awj)

Cw=∑(twj*Awj)/∑ E₀=1/Ai*Cw*F
W*βc(N/mm²)

43
2
1
4
3
2
1

2.89
1.80
1.33
1.15
1.58
1.15
0.87
0.62

XY

4.90E+07
6.00E+07
6.65E+077.67E+07
3.16E+07
3.85E+07
4.36E+07
4.17E+07

1.81
1.28
1.11
1.15
0.99
0.82
0.73
0.62

SD1111111
1T

Is=E₀*SD*T
11
1
11
1
1
1Is₀ Evaluation

1.81
1.28
1.11
1.15
0.8
0.99
0.82
0.73
0.62

OKOKOKOKOKOKNGNG

4.1 WRC Second level screening procedure
For this 2nd screening procedure the seismic index of structure is calculated by Eq. (1). At this level ofevaluation the structure shows damage in the first and second floors that is given in following Table 2.
Table 2. Seismic index Is of structure.
Direction Floor ∑Qu (N)XY43214321

8.98E+07
1.04E+08
1.19E+08
1.36E+08
1.74E+07
2.11E+07
2.45E+07
2.77E+07

group C₁Calcu Demand
Is=E₀*SD*
E₀⁼1/Ai*√(C₁*F₁)² SD T
Is₀Evaluation((∑Qu)/(∑W))
lated Ctu*SDT
1.91E+07
4.71
4.42 1 1
4.42
4.71
OK
3.65E+07
2.85
3.06 1 1
3.06
3.42OK
0.60
0.30
5.45E+07
2.19
2.63 1 1
2.63
3.06
OK
7.30E+07
1.86
1.86 1 1
1.86
2.98OK
1.91E+07
0.91
0.85 1 10.85
0.91
OK
3.65E+07
0.58
0.87 1 1
0.87
0.69
OK
0.30
0.60
5.45E+07
0.45
0.56 1 1
0.56
0.63
NG
7.30E+07
0.38
0.57 1 1
0.57
0.61
NG

∑Wi (N)

5. STRUCTURAL EVALUATION GUIDE IN DOMINICAN REPUBLICThe Detail Evaluation is used on the condition that the Seismic Design Code is accomplished. Staticanalysis of progressive push (Pushover) can be applied in the Dynamic method, which was used forthis process. This assessment requires the capacity and establishment of the structure to the maximum
horizontal force generated for design force, through the application for increasing the lateral force, andtotal maximal strength should be equal to or less than to the base shear given by Eq.(3).
The result of the evaluation is shown in Table 3. The result indicates that the structure hasdamages only on the first floor.

V = Cb * W

N

W = ∑ WiI =13(3)Table 3. Shear base of existing structure
ExistingStructure

Direction

Type of structure

T (s)

CbX

Special reinforced
concrete walls

0.146

0.207

13821

0.235

0.281

18808

YV (KN)

5.1 Comparison method between Japan and Dominican Republic
The method used in Japan is more detail because it has values to classify the failure and to determine
the percentage of damage in each structural element to obtain the level of behavior of the structure.
While in the Dominican Republic, the method used is only parameters that applied to determine thebehavior of its structures. The procedure to evaluate structures in Japan is stricter, due to that it
demands a high percentage of performance in the elements that integrate the structure.

5. ANALYSIS RESPONSE SPRECTRAL OF STRUCTURE
In the static and dynamic analyses by the program Stera 3D, the results indicate that on the first andsecond floors, the structural elements can have severe damage, due to flexural yielding at wall baseand the elements resistance loses capacity with relation to the imposed demand. In this case, they do
not transmit loads axial to the elements without losing its elastic range. For the reinforcement of thisstructure we will use shear wall to increase the strength of the walls and the performance of thebuilding. This type of shear wall is a method with easy application that technology and is especially
economical, therefore this method would be very feasible in the Dominican Republic.
According to the previous calculations the building only needs rehabilitation on the firstand second floors in the transverse direction (Y). But for better structural behavior, the rehabilitation isrealized in the whole floors in the mentioned direction to increase, the quantity of structural walls
which have following conditions: thickness of 250mm, compressive strength of concrete is 28N/mm²,
yield strength of reinforcement is 420 N/mm², diameter of horizontal and vertical reinforcement bars is
9.52, reinforced spacing to 200mm. On the first floor eight walls are placed, and on the second andthird three walls, and the fourth floor one wall is placed.
.

Figure 4. Displacement in transverse Y.

Figure 3. Displacement in longitudinal X.

The performance of the building before and after rehabilitation is different with respect tothe displacement as shown in Figure 3 and 4. In transverse walls, the rehabilitation for the diminisheddisplacement is realized, but in longitudinal walls, rehabilitation do not make the displacement

4increase, as this must be for the force that the transverse walls in the longitudinal walls.

6. GUIDELINE OF REHABILITATION EXISTEN REINFORCED BUILDING
The rehabilitation in the program Stera 3D is realized, and returns to compare the results of theprogram with the new results of the theoretical calculations to determine the index of demand which
are needed in order that the building has a good behavior by this way in case those earthquakes occur.
6.1 WRC First level screening procedure
Table 4. Comparison of seismic index
BEFOREAFTER REHABILITATIONThe resistance of the structure was evaluated based
Direction floor Is=E₀*SD*T Is=E₀*SD*T Is₀ Evaluation on the force of the floors upon the tension realized inevery structural element; with the purpose of finding
41.81
1.84
OK
weak connections and of identifying its behavior
3
1.28
1.32
OKX
2
1.11
1.14
OK
which affects the answers of the structural system of1
1.15
1.20
OK0.8
the building. As shown in Figure 5 and 6, for the first
40.99
1.01
OKlevelprocedure the performance of the building after
30.82
0.97
OKY
20.73
0.84
OKretrofitting the seismic demand index is correct.
10.62

0.83

OK.

Figure 6. Demand capacity of building in X
direction.

Figure 5. Demand capacity of building in Y
direction.
6.2 WRC Second level screening procedure

Table 5. Comparison of seismic index
AFTER REHABILITATIONBEFORE

Direction Floor Is=E₀*SD Calculated Is=E₀*SD*T Is₀ Calculated Demand Evaluation*T
Ctu*SD
Ctu*SD Ctu*SD
4
4.42
4.71
4.52
4.83
OK3
3.06
3.42
3.08
3.45
OKX
22.63
3.06
3.85
4.49
OK1
1.86
2.98
2.71
4.34
OK
0.60
0.3040.85
0.91
0.91
0.97
OK3
0.87
0.69
0.93
0.75
OKY
2
0.56
0.63
0.93
1.04
OK10.57
0.61
1.04
1.11
OK5

The rehabilitation of transverse walls on all stories was performed, and the behavior of the building
after retrofitting satisfied seismic demand index, which is correct for the second level procedure.

7. CONCLUSION
The aim of this study is to learn the methods of seismic evaluation in Japan. To verify theperformance of the structure is to compare the result with the response of the program Stera 3D. Thenthe methods is used to compare with the one used in the Dominican Republic to determine which
conditions are needed for the seismic evaluations to realize in the country. Since the visual evaluation
is simply of high quality, then evaluation by the comparison would have to be done by the detailed
evaluation that uses the seismic code. The methods used in Japan are a Model of well-structured andwell-ordered evaluation by which good quantitative results are obtained.
It is necessary to evaluate the seismic vulnerability in the Dominican Republic to maintaincontrol on the conditions of the buildings. In addition there are a lot of structures in the country but
many of them are made of reinforced concrete and designed without any seismic codes. For this reason
it is important to determine and to improve the seismic capacity of all these existent buildings thatmight be of high risk in case of earthquakes.

8. RECOMMENDATION
The main goal of the evaluation is to determine the response of the building during the earthquake. Itis very important that the buildings have a sufficient capacity deformation to withstand seismic
demand properly without deteriorating its strength.
i.
Designing structure elements (column) with greater capacity than beams, stirrups suggested
well distributed, adequate additional steel, so they can support maximum loads anddeformations avoid total collapse of the structure.
ii.
It is necessary to evaluate all structures in the country that are designed before the first seismiccode and perform rehabilitation.
iii.
All structural projects should be designed by taking into account country’s current seismiccode and all previous constructions should be checked in accordance with the code.
iv.
Developing more rigorous seismic assessment model with more detailed values.

ACKNOWLEDGEMENT
I am very thankful to my advisor and supervisor Mr. Mizuo INUKAI for his patience and for guiding
me in this process and giving me all advices during my study

REFERENCES
Japan Building Disaster Prevention Association (JBDPA), 2005, Simple Standard for Seismic
Evaluation of Existing Shear wall Reinforced Concrete Buildings
Japan Building Disaster Prevention Association (JBDPA), 2001, Seismic Evaluation and Retrofit
Japan Concrete Institute, 2007, Seismic Rehabilitation of Concrete Structures, edited by Shunsuke
Sugano.
Ministry of Public Works, 2011, R-001 Seismic design code Regulations, Dominican Republic
Ministry of Public Works, 2011, R-033 Concrete Regulations, Dominican Republic
Saito.: STERA_3D Ver.5.9 User Manual, Building Research Institute, Japan6