Typological Inventory of Residential Reinforced Concrete Buildings for the City of Potenza

Major earthquakes occur somewhere every year with accompanying devastations. For example, the center of the city of Managua was destroyed completely in December 1972 with the loss of more than 15,000 lives. Government buildings also did not escape destruction which brought about a paralysis in Governmental functioning for a short time. In April of the same year, in Iran an earthquake of magnitude 6.9 attacked the town of Ghir causing the loss of 5,000 lives. Large earthquakes accompanied by large losses of life occur frequently in Iran. Another type of earthquake destruction was caused in Peru in 1970 resulting in the loss of more than 50,000 lives under a huge mud slide that accompanied the big earthquake. In 1971, the San Fernando Earthquake, in the U.S.A. caused very heavy damage to the modern reinforced concrete buildings and highway overpasses calling serious attention to the devastation which might be brought about in modern large cities if a destructive earthquake should occur. The figure for lives lost by the San Fernando earthquake was small, assisted by the extremely lucky time of the occurrence of the earthquake at 6 A.M., when daily activity had not yet started. In 1968 an earthquake occurred in the city of Manila, the Philippines, crashing down completely an apartment house burying 260 people under the debris together with the destruction of many large reinforced concrete buildings. In the same year another big earthquake occurred in the northern part of Japan causing very heavy damage to the reinforced concrete buildings, all of which had been designed to resist earthquake force according to the Japanese regulations for antiseismic design. Repeated destruction of reinforced concrete buildings by earthquakes in recent years has caused a questioning of construction engineering. Such heavy destruction as experienced by reinforced concrete buildings in this earthquake (buildings which were designed and constructed under the antiseismic regulations) raised serious discussions among Japanese earthquake engineers which call for urgent studies. In Table 1 is shown a list of earthquakes that have resulted in heavy destruction since 1960. It may be surprising to find that about 20 earthquakes are included in the table showing that an average of three earthquakes of a destructive nature occurs somewhere on earth every two years. According to UNESCO statistics, between 1926 and 1950 over 350,000 people were killed by earthquakes, and the damage to buildings and public works totaled nearly $ 10,000 million. In proportion to the spread of urban civilization throughout the world, the toll taken by these destructive earthquakes has been steadily increasing and will increase more rapidly in the future. The only way to ensure against these substantial economic losses is to design and build, and to strengthen existing buildings, in such a way that the structure will resist the seismic forces to be expected in each area.

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Irregularity of the Distribution of Masonry Infill Panels and Its Effect on the Seismic Collapse of Reinforced Concrete Buildings

Applied Sciences ◽

10.3390/app11188691 ◽

2021 ◽

Vol 11 (18) ◽

pp. 8691

Author(s):

Juan Carlos Vielma ◽

Roberto Aguiar ◽

Carlos Frau ◽

Abel Zambrano

Keyword(s):

Reinforced Concrete ◽

Structural Response ◽

Practical Reasons ◽

Reinforced Concrete Buildings ◽

Masonry Infill ◽

Concrete Buildings ◽

Infill Panels ◽

Open Plan ◽

Collapsed Buildings ◽

The City

On 16 April 2016, an earthquake of Mw 7.8 shook the coast of Ecuador, causing the destruction of buildings and a significant number of casualties. Following a visit by the authors to the city of Portoviejo during the debris removal and recovery stage, it was noted that several reinforced concrete buildings located on corners had collapsed in the central part of the city. These buildings were characterized by the presence of masonry at the edges of the buildings but not between the two mostly open-plan facades on the corner for practical reasons. This article reviews the effect of masonry infill panels on the seismic response of reinforced concrete structures. For this, a model that contains the geometric and mechanical characteristics typical of collapsed buildings was generated and subjected to nonlinear analysis, with both static and dynamic increments. The results show the clear influence of the masonry infill panels on the structural response through the torsional behavior that is reflected in the evolution of the floor rotations. Finally, dynamic incremental analysis is used to obtain the collapse fragility curve of the building, and a new damage measure based on floor rotations is proposed.

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Seismic Vulnerability and Risk of Losses Case Study Center of the City of Azogues

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1203/3/032124 ◽

2021 ◽

Vol 1203 (3) ◽

pp. 032124

Author(s):

Carlos Julio Calle Castro ◽

Juan Sebastián Maldonado Noboa ◽

Luis Mario Almache Sánchez

Keyword(s):

Reinforced Concrete ◽

Seismic Performance ◽

Seismic Vulnerability ◽

Fragility Curves ◽

Inelastic Behavior ◽

Reinforced Concrete Buildings ◽

Concrete Buildings ◽

Capacity Curves ◽

Performance Point ◽

The City

Abstract Ecuador is located in the Pacific Ring of Fire, a country with high risk and seismic sensitivity, evidenced by the 6.8-degree earthquake in Ambato in 1949, which left approximately 6000 dead, the 7.8-degree earthquake in Manabí and Esmeraldas in the year 2016 with 663 victims and 29672 buildings without the possibility of use. Currently there is a problem about seismic performance in reinforced concrete buildings, since many were built with old regulations; so, it is necessary to assess their vulnerability. Quito, Guayaquil and Cuenca, large cities in Ecuador, have formal studies of seismic vulnerability, mostly carried out by university students and teachers. In contrast, most small cities do not have these studies; or, they need to be updated to validate their results. This is the case of the city of Azogues. The objective of this research is to evaluate the vulnerability of structures using the Hazus methodology, adapted to Ecuador, in the downtown area of the city of Azogues, in structures located around the Central Park, to establish the seismic performance in reinforced concrete buildings. The Hazus methodology, which determines the vulnerability of buildings from fragility curves, which are entered with inputs as the capacity, performance level and drift curves calculated through Ecuadorian models. The capacity curves, depending on various aspects such as: the material, number of floors, spans between columns, among others; they vary from building to building. In this sense, capacity curves were defined for sets of buildings with similar characteristics, coinciding with the Hazus methodology. The performance levels and the displacements were calculated with the ETABS computer package. For fragility curves, the model that most real simulates the response of a structure is the non-linear analysis, because it considers the decrease in stiffness in columns and beams, as well as the deterioration of the properties of the materials. In this sense, there are fragility curves of Ecuadorian buildings for four levels. The earthquake readings enable the construction of a demand spectrum, which, when contrasted with the capacity spectrum, leads to the performance point. Its position sometimes varies per the elastic demand spectrum, which is diminished by its inelastic behavior. As the demand spectrum decreases, the damage will increase. Once the coordinates of the performance point are known, the fragility curves are used; and, the possible damages are defined, quantifying them in percentage.

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