Investigation of The Critical Angle of Seismic Incidence for The Seismic Safety Assessment of Asymmetric Reinforced Concrete Buildings with Re-Entrant Corner Plan Configurations

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In this thesis, the methodology to estimate the possible critical angle of seismic incidence and its corresponding structural demand has been investigated in the context of LTHA, to assess the seismic behavior of asymmetric reinforced concrete buildings with re-entrant corner plan configurations under different orientations of seismic excitation. This was done by defining the structural demand as the function of input seismic incidence angle ( ) with in the range (0 0 , 180 0 ) at 15 0 increment, in order to assess the seismic incidence angle that leads to the maximum global and local structural demand of reinforced concrete buildings under different orientations of seismic excitation. To do so, different 3D computer model of single and four-story symmetric (torsionally stiff) and asymmetric (torsionally flexible) reinforced concrete buildings has been generated with the aspect of changing plan configuration. Finite element based linear time history dynamic analysis were carried out to assess seismic response of the structural model in all cases with the help of elastic demands (maximum story drift, and maximum column axial force, torsion & moment), by using ETABS.V16 software. It is observed from the study that, the structural demand produced varies as a function of input seismic incidence angle and the highest demand occurs in the most flexible structural direction. The structure gets its maximum value of column axial forces, torsion and moment with a specific angle of seismic excitation which is different for different shapes of building as well as from column to column. It is concluded from the study that the angle of seismic incidence input motion considerably influences the response of RC structures. Additionally, considering ASIcri values of all models, asymmetric buildings with re-entrant plan have shown considerable change in maximum column axial forces and moment due to the change in building plan configurations & column locations. But, among various internal forces irregular buildings with re-entrant corner plans are more sensitive to the maximum column torsion when compared with corresponding regular building.



Seismic incidence angle, re-entrant corner plan, linear response history analysis