Effect of Presence of Subsoil Voids on the Seismic Performance of Reinforced Concrete Buildings Considering Different Building Structural Systems

The presence of underground voids beneath reinforced concrete structures causes many problems in settlement under the foundations, which may cause tilting problems and affect the building's stability, especially if these buildings are subjected to seismic loads. In this paper, three-dimensional seismic analyses of RC structures founded on soil containing voids were performed using the finite element method (FEM). Two buildings with the same slab area (20*20) m ² were considered in the analysis. The first building is a six-stories building while the second building is a fifteen-stories building. The buildings were exposed to the ground acceleration for the El-Centro earthquake with a time interval of 0.02 sec. The buildings were rested on clay soil with two different critical locations of weak soil region (underground void) and one analysis on the soil without a void. Several factors that affect the seismic performance of structures, such as void locations, structural systems of the buildings, the effects of infill brick walls, foundation level, and the number of floors were considered. These factors were considered in the analysis to obtain a complete description of the seismic response of the structures constructed on soil with voids to be used in design processes. Based on the results, charts were developed for the seismic response of RC structures built on soil containing voids. These charts could be used in the prediction of the seismic response of structures built on soil with voids.