The fragility curves for low-rise reinforced concrete buildings in Libya

Abstract

In the last century with the huge development in building materials, people used reinforced concrete to provide strong buildings for themselves. These buildings can stand against nature phenomena such as winds, rain, snow, etc. For the effect of earthquakes, these buildings must be considered during design to tolerate collapse and avoid damage and lives. This study uses a new technique to develop a method that can measure the percentage of damage under earthquake motion. Using nonlinear analysis for target buildings and generating push-over curves for these houses to generate earthquake_based fragility curve. Moreover, the calculated fragility curve can help to evaluate these buildings by estimating the percentage of damage caused by a certain level of the earthquake, which leads also to help the designers to review the way to enhance the seismic performance of these buildings, as well as adding new parameters in future building code for design taking into consideration earthquake affect. The first chapter discusses the background and scope of the earthquake history in Libya over the years. This chapter define the region of Libya seismically and describe its activity regarding earthquakes. In addition to that, some of these earthquakes caused damage to the region through loss of lives or properties. This information represents the importance of this study. In the second chapter, the style of the buildings in Libya is shown including materials that have been developed over the years. In this chapter, it is necessary to know the type of structures that will be exposed to the effects of earthquakes when they occur. In the third chapter, the methodology of measuring the fragility curve and estimating damage is described. Definition of FEMA HAZUS loss estimation methodology for calculating the fragility curve, and the different levels of damage. The calculation of the fragility curve depends on push-over analysis results which are calculated using software SAP2000. In the fourth chapter, the description of this study case's building is given. The dimensions and properties, as well as the number of stories and the definition of loads. In this study, two types of buildings are primarily used by locals in Libya for residential buildings. To determine a push over or capacity curve for the case study building, we model the two buildings and define loads, hinges, and materials' details. After calculating the capacity curve, using FEMA HAZUS loss estimationmethodology to generate the estimated fragility curve based on the damage percentage of the building related to corresponding drifts. The performance point can be calculated at the intersection of capacity curve and demand curve for the common maximum earthquake in the region given by the spectral acceleration. Using the calculated spectral displacement at the performance point caused by the maximum earthquake in a region, we can estimate the percentage of damage to the building.