Biaxial seismic interaction of corner reinforced concrete buildings

The objective of the present paper is the evaluation of the seismic response of reinforced concrete corner buildings interacting with adjacent structures along two orthogonal directions (biaxial seismic interaction). For this purpose, two 8-storey corner buildings, one with soft ground storey and one fully infilled with masonry panels, are designed according to current European standards. The corner buildings under consideration are supposed to be in contact with lower structures in many alternative ways, formulating various cases of biaxial seismic interaction. All structural systems are analyzed by means of inelastic dynamic step by step analysis for concurrent action of two horizontal accelerograms applied with four alternative orientations. The response of the corner buildings is assessed through the calculation of crucial response quantities. The whole study demonstrates the importance of biaxial seismic interaction which might amplify up to about four and ten times the internal forces and deformations, respectively. It also highlights the role of several factors such as the unfavorable soft-storey effect which might increase the column shear deformations twentyfold and the role of the ground motion orientation. Finally, it indicates that the phenomenon is much more severe in comparison with the well-studied uniaxial seismic interaction between adjacent structures since it produces up to nine times larger response quantities.