Pushover (PO) is a well known and practical analysis for evaluating new or existing buildings. The conventional pushover predicts the seismic demands well in the 1st mode dominant building, and will produce larger error as the higher mode effect contribution increases. This research tries to overcome the weakness based on the observed behavior of the structures in nonlinear dynamic analysis. Two-, 8-, and 20- storey RC frame buildings with 0%, 5%, 10%, 15% of eccentricity for each building subject to nonlinear response history analysis (NRHA) are used. An inelastic response spectrum which is used in the extended N2 method is also used in this research. Because of the one way computation, no iteration is needed. Four modifications are made to take account the higher mode effects both in elevation and in plan which are based on the observed behavior. The assumption that higher mode effect will keep in elastic behavior used in the extended N2 method is eliminated. The modifications are verified in a 14-storey building with 10% eccentricity with medium and high inelastic degree of the structure. Displacement and drift at center of mass, and coefficient of torsion are used as the seismic demands parameter. The results show that the proposed method can give better accuracy towards the actual behavior of the structure and keep the simplicity of the PO method.

Pushover (PO) is a well known and practical analysis for evaluating new or existing buildings. The conventional pushover predicts the seismic demands well in the 1st mode dominant building, and will produce larger error as the higher mode effect contribution increases. This research tries to overcome the weakness based on the observed behavior of the structures in nonlinear dynamic analysis. Two-, 8-, and 20- storey RC frame buildings with 0%, 5%, 10%, 15% of eccentricity for each building subject to nonlinear response history analysis (NRHA) are used. An inelastic response spectrum which is used in the extended N2 method is also used in this research. Because of the one way computation, no iteration is needed. Four modifications are made to take account the higher mode effects both in elevation and in plan which are based on the observed behavior. The assumption that higher mode effect will keep in elastic behavior used in the extended N2 method is eliminated. The modifications are verified in a 14-storey building with 10% eccentricity with medium and high inelastic degree of the structure. Displacement and drift at center of mass, and coefficient of torsion are used as the seismic demands parameter. The results show that the proposed method can give better accuracy towards the actual behavior of the structure and keep the simplicity of the PO method.

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