COMPARISON OF FORCE BASED DESIGN AND DISPLACEMENT BASED DESIGN METHODS FOR SEISMIC RESPONSE OF MULTISPAN BRIDGES

Abstract

Multispan bridges are very common structures in transportation system. Generally, all the bridges are designed using force-based design (FBD) method. Though displacement correlates damage better than strength does, FBD assumes damage in the structure is controlled by the provision of strength and uses displacement as the final check to determine the structural performance. Although current FBD method is considerably improved, there are some fundamental problems in its procedure. Displacement-based design (DBD) methods have been developed overcoming deficiency associated with FBD method. In this study, two DBD methods, direct displacement-based design (DDBD) and alternative displacement-based design (ADBD), have been compared with FBD method for the seismic response of multispan bridges. Two different configurations of bridge models are considered here to compare their seismic response. Base shear and displacement are taken as primary seismic response parameter for this study. From the numerical evaluation it can be concluded that, DBD methods have shown better performance in calculating seismic responses than FBD method. Base shear calculated by DDBD and ADBD methods are less than that calculated by FBD method, whereas displacement estimated by DDBD and ADBD methods are more than that estimated by FBD method.