The occurrences of (M-w = 7.4) Kocaeli and (M-w = 7.1) Duzce earthquakes in Turkey in 1999 once again demonstrate the nondamaged and high performance conditions of RC shear wall dominant structures commonly built by using the tunnel form technique. This study presents their seismic performance evaluation based on the nonlinear pushover analyses of two case studies. The contribution of transverse walls and slab-wall interaction during the 3D action, the effects of 3D and 2D modeling on the capacity-demand relation, as well as diaphragm flexibility, torsion and damping effects were investigated. An effort was spent to develop a shell element having closing-opening and rotating crack capabilities. This study shows that the applied methodology has a considerable significance for predicting the actual capacity, failure mechanism, and evaluation of the seismic response of tunnel form buildings. (C) 2003 Elsevier Science Ltd. All rights reserved.