Application of normal flow algorithm in modal adaptive Pushover analysis

In this paper, a load increment method for Modal Adaptive Pushover Analysis (MAPA) for plane frame buildings is presented. In this method, the Newton-Raphson iterative algorithm is used along the flow path normal to the Davidenko curves with modified convergence rate. Contrary to the previous arc-length methods, this algorithm, which uses the Homotopy approach, is based upon the new mathematical concepts. In order to evaluate the proposed method, two steel frames are analyzed using the algorithm presented and the results are compared with Non-linear Dynamic Analysis (NDA), FEMA-273 Nonlinear Static Analysis (NSA) and the Modal Pushover Analysis (MPA) procedures. When the NDA results are taken as reference, it is seen that the proposed method is capable of estimating efficiently the seismic response of frame buildings with moderately good accuracy.