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We'd like to understand how you use our websites in order to improve them. Register your interest. The island of Hispaniola, shared by the Dominican Republic and Haiti, is located in a subduction zone between the North America plate and the Caribbean plate.
In addition, there are 13 geological faults in the interior of the island, some of which have shown the potential to generate earthquakes of magnitude 7. Thus, the whole island is considered to be a high seismic risk region. In the case of the Dominican Republic, two earthquakes stand out: a magnitude 8.
Among the observed effects, the partial and total collapse of several school buildings had a remarkable impact on local communities. During these three decades, thousands of structures were built nationwide, including essential facilities such as hospitals and schools.
Considering that the current student population in public schools in the Dominican Republic is over 2 million, with the majority attending buildings that were designed with the seismic code and which proved to be highly vulnerable during the Puerto Plata earthquake, it is vital to take measures that reduce the risk and minimize potential earthquake damage to school buildings.
The latter schools were all built prior to the adoption of the current updated seismic code. This paper presents the results of the assessment of the Fernando Cabral Ortega School.
Although only the results of a single RC building are presented, the response of such structure can be considered representative of a portfolio of existing schools in Dominican Republic. There are 13 geological faults in the interior of the island Fig.
In the case of the Dominican Republic, two earthquakes have occurred in the last decades: a magnitude 8. Image adopted from Google Earth. Adapted from COE Within the affected school buildings can be mentioned La Reforma School which experienced the collapse of the first floor level Fig.
Affected school buildings after the 6. And San Marcos School: d several columns were affected by the short column effect. Also, damage in schools not only occurred in the city of Puerto Plata. However, despite of the observed damage, only the death of a person who was staying overnight in a motel that collapsed was recorded Almeida If the earthquake had occurred during the day, a great national tragedy could have happened, where the victims would have been counted by thousands.
In the Latin American region, school buildings are of great importance since, in addition to teaching, they are used as shelters in the face of natural phenomena such as hurricanes and earthquakes. Additionally, the evaluation of structural vulnerability of school buildings has focused the attention of researchers worldwide and hundreds of studies have been carried out around the world in terms of earthquake damage reports and vulnerability assessments of school buildings Rodgers In the last decade, some of the conducted research has been focused in the assessment of damaged school buildings by means of qualitative method Formisano ; the evaluation of retrofit schemes Formisano et al.
Formisano assessed qualitatively 15 school buildings located in several municipalities of San Pietro, Italy, that were affected by the earthquake occurred on May 20, The results of the study indicated that all the evaluated structures showed structural schemes and constructive details that did not comply with the current Italian seismic code.
It is recommended to retrofit such structures using simple schemes such as the casing of masonry walls with steel plates, as well as the use of tie beams to improve the connection between the walls, among others.
Likewise, Formisano et al. Such structure was composed by several modules and was designed for gravity load only. One of the modules was retrofitted with different techniques, with the objective of assess the behavior of each technique and select the best one in terms of economic, structural, and environmental point of view. It was found that the best retrofit solution was the buckling-restrained braces.
The influence of different modeling choices and material properties uncertainties on the seismic assessment of an existing RC school building was evaluated by Maracchini et al.
The authors found that mechanical properties of concrete and steel strongly affect the seismic risk index. The evaluation included the development of detailed numerical models and the use of sophisticated analysis tools, which included an incremental dynamic analysis. The models were validated and calibrated from the results obtained from the measurement of ambient vibrations.
A total of schools were assessed, using an adaptation of the rapid visual detection method FEMA a , b together with other evaluation methodologies Lew et al. The project also included the classification of the structures according to their vulnerability index Benedetti and Petrini which takes into account aspects of structural type, structural configuration, location of the building, foundations and non-structural elements.
The results indicated that schools Likewise, the assessment of the vulnerability index showed that 53 schools The authors recommended a detailed evaluation of the buildings that resulted with a high vulnerability degree.
Vulnerability studies using qualitative methods constitute a first stage of evaluation when there are a large number of structures to be evaluated and limited resources are available. However, in order to make recommendations for reinforcement, a more detailed analysis is necessary, which was not contemplated within the objectives of the ONESVIE school evaluation project. Therefore, the aforementioned study should be completed in a second stage that includes the quantitative evaluation of each of the schools that resulted with a high degree of vulnerability and that proposes particular solutions based on the results of the analyzes of each one of the assessed schools.
Considering that the current student population in public schools in the Dominican Republic is over 2 million, with the majority attending buildings that were designed with the former seismic code and which proved to be very vulnerable during the Puerto Plata earthquake, it is deemed vital to take measures that reduce the risk and minimize potential earthquake damage to these structures.
The case study schools were all built prior to the adoption of the current seismic code, which resulted in a higher degree of vulnerability according the study carried out by ONESVIE.
The specific objectives established in order to achieve the main objective of this project are: a to determine whether the schools are adequate according to the current Dominican seismic code ; b to update structurally schools that do not comply with the Dominican seismic code and provide the structural solutions if necessary.
During these three decades, thousands of structures including schools were built throughout the national territory that may be vulnerable to a seismic event. Following sections briefly discuss the main features of both the Seismic Code Provisional Recommendations and the current Seismic Code implemented in , as well as two important seismic hazards studies carried out in both sides of the Hispaniola Island. The provisional recommendations for the seismic analysis of structures SEOPC divide the country into two seismic zones: 1 high seismicity and 2 medium seismicity zone, as shown in Fig.
The design spectra, both elastic and inelastic, are shown in the same figure. It is important to mention that the U -, S -, and R d -coefficients are tabulated values that depend on the importance of the structure, the site in which the structure is located, and the type of structural system, respectively. Alternatively, for design purposes, the use of spectral iso-acceleration maps is allowed for short periods S S and long periods S 1 , as shown in Fig.
The expressions that define the elastic design spectrum are shown in Fig. In the figure, F a and F v are the site coefficients, which depend on the site classification. Likewise, U represents the use of the structure, means while R d is the energy dissipation factor that is a function of the structural system. It is important to mention that the current seismic code is not intended for the evaluation of existing structures; thus, the evaluation of the seismic risk of as-built schools may become controversial, especially for the estimation of the hazard levels.
Adapted from MOPC Considering that, as first estimate, the fundamental period for a reinforced concrete RC frame structure can be evaluated as 0. Thus, it is necessary that school buildings designed with the former provisional regulations need to be assessed in order to determine the degree of vulnerability that such structures pose.
After the devastating earthquake magnitude 7. Although the maps were developed for the entire island of Hispaniola, the authors indicate that they cannot be considered as complete hazard maps for the Dominican Republic since they do not take into account all the sources of earthquake hazard that affect the eastern of the Hispaniola.
The proposed maps are depicted in Fig. Adapted from Frankel et al. Thus, it is possible to relate the accelerations proposed in the R seismic code with the ones developed by Frankel et al.
The comparison for the case of the long-period spectral acceleration is shown in Fig. It is observed that the current seismic code has higher accelerations around the northern fault northwest and northeast of the Dominican Republic. However, outside this region, the acceleration contour proposed by Frankel et al.
The same conclusions apply for the case of the short-period spectral acceleration Fig. Comparison between the contour accelerations of the seismic hazard maps developed by Frankel et al. The methodology implemented in the study presented in the previous section is summarized as follows:. The above framework fulfills the current practice for seismic assessment of existing RC buildings also in the earthquake-prone regions in the south of Europe e.
The details of each of the above-mentioned steps are presented in the following sections. To ensure that the selected schools are the most critical, they must meet the following selection criteria:. The year of construction must be before It is assumed that the structures built with the current code are not vulnerable. Due to the low probability that architectural plans are available, it is proposed to perform an architectural survey to identify both the gravity and the lateral load resistance systems as well as to obtain the dimensions of the structural elements.
In accordance with the requirements for the evaluation of existing buildings MOPC established by the Ministry of Public Works of the Dominican Republic MOPC Spanish acronym , the structural survey for RC structures shall include the assessment of the structural member conditions, the evaluation of concrete strength of the structural components, as well as the evaluation of the reinforcement steel.
Due to budgetary constraints, it was not possible to reach the minimum number of concrete core samples as required by the MOPC. However, to obtain a representative concrete strength for modeling purposes, a minimum number of three sample tests were established by structural elements as suggested by FEMA , Such elements were selected based on a preliminary structural analysis.
At the same time, for the same reasons, it was not possible to carry out the inspection of the foundations. To optimize the number of concrete samples, a preliminary structural model was implemented numerically with the main objective to identify those structural elements with the higher load demands that will be selected for a destructive-type test.
With the properties of the concrete obtained from the structural assessment and the arrangement of the reinforcing bars in the structural elements determined from the scanning of such elements, a refined analysis model was constructed which includes the seismic loads demands according to the current seismic regulations.
If the results of the structural analysis indicate that the building system does not comply with the requirements of the R regulations, a structural solution will be proposed.
Next section shows the assessment of the Fernando Cabral Ortega School by applying the methodology previously described above. The structure has a capacity for students and was built in The structure consists of three building modules of two levels each connected by a corridor as shown in Figs. The structural system is composed by RC frames in both directions enclosed by masonry walls. It can be noticed that the structures satisfy the established selection criteria. The structural drawings of the sample building were not available; therefore, the cross-sectional dimensions of the elements, the concrete strength, and the reinforcement details were obtained from both the architectural and structural surveys, respectively.
The cross sections of beams and columns are depicted in Fig. The concrete strength was assessed by means of destructive test. A total of six samples were evaluated three in beams and three in columns , in structural elements that resulted with higher load demand according to a preliminary structural analysis.
The concrete core extraction process is shown in Fig. In order to evaluate the behavior of the building structure, a numerical finite element model was created using the ETABS software Computer and Structures Such model is shown in Fig. Beams and columns were modeled according to the sections as depicted in Fig. In both elements, the cracking effect as required by the R was considered.
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Seismic risk of critical facilities in the Dominican Republic: case study of school buildings
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