Nayer A. EL-Esnawy
Structural Engineering Department, Faculty of Engineering, Cairo University, Giza, Egypt
An adaptive pushover procedure incorporating a weighted vector combination strategy of the modal
lateral forces for multistory frame buildings is presented. In the proposed pushover procedure, the
lateral force distribution prescribed along the height of the frame building is continuously updated by
combining the instantaneous modal forces based on the current stiffness and dynamic characteristics
of the building. Unlike standard modal combination rules such as the SRSS and CQC, the weighted
vector combination strategy preserves the sign of each contribution of the modal forces.
The accuracy of the proposed adaptive pushover procedure to evaluate the base shear capacity, floor
displacements and interstory drifts for several low- to medium-rise multistory steel buildings is
validated by comparison with the results determined by nonlinear dynamic analyses using a set of
earthquake ground motions. Also, results obtained by different conventional and adaptive pushover
procedures are shown. It is concluded that the proposed adaptive pushover procedure is a better
alternative to nonlinear dynamic analyses than conventional pushover procedures for seismic
assessment of the performance of multistory frame buildings, considering linearly-elastic and inelastic
states of deformation.