Seismic damage assessment for thin-walled reinforced concrete buildings in urban areas in Peru

Peru is constantly subjected to severe earthquakes due to its close location to the Ring of Fire. Analysis of historical records as well as the study of the performance of structural systems have served as a basis for the development of seismic design code provisions. The main goal of these provisions is to reduce seismic risk. The lack of housing in Peru and the growth of population are the reasons for permanent housing demand. Thin-walled reinforced concrete dwellings are mostly preferred by contractors and builders due to their short execution time, simple construction procedures and minimum construction costs. It is known that these thin walls have very limited ductility because of the properties of the one-layer reinforcing steel layout. There is an almost 50-year seismic gap in the north region of Peru, where most of the thin-walled buildings are built. Hence, these thin-walled dwellings have not been subjected to strong accelerations yet. Therefore, we do not have enough information about their performance. Some laboratory tests have been carried out to assess the mechanical properties of individual natural scale walls. These tests were conducted under the provisions of FEMA 461. This paper mainly focuses on the development of fragility curves for thin-walled buildings. In this research, fragility curves are generated by a Montecarlo simulation technique. Fragility curves are generated for 2 types of building layouts. Type 1 consists of three 2-story blocks which share dividing walls and Type 2 considers a 3-story independent block. These are the most common layouts offered by the current housing market and have been built since the 90s. These dwellings are usually built on S2-type soil, which is and intermediate between soft soil and rock. The most important contribution is the probabilistic approach used in this method. This considers randomness and uncertainty of mechanical properties of the materials involved such as compressive concrete strength and yield stress of the reinforcing steel. Also, this approach is applied to the seismic demand through the generation of artificial ground motion signals. Both types of structures show excellent performance during the design earthquake.