COMPARISON BETWEEN FORCE BASED AND DIRECT DISPLACEMENT BASED DESIGN FOR R.C FRAME STRUCTURES

Force-based design FBD, of reinforced concrete buildings subjected to seismic loads, suffers from many problems such as the assumed stiffness of the structural elements, inappropriate R-factor, and others. These problems resulted in the need for an alternative design approach. This resulted in the introduction of the performance based design PBD. The Direct Displacement-Based. Design DDBD which is the subject of this paper is based on PBD. This method is characterized by its clear procedures which can be applied to different types of structures. The DDBD gives accurate solution for a certain category of structures since the damage of different structural elements is related to the maximum strain at these elements. The objective of this paper is to apply DDBD on different reinforced concrete frame buildings. The base shear force calculated by DDBD are compared with those calculated by FBD. 1bree computer programs have been used in analysis of the studied buildings to perform a pushover analysis and to get the displaced shape corresponding to the drift limit at the first floor. The results of the analysis show that the DDBD is suitable for moment resisting frame buildings with number of storeys more than 8 subjected to high values of ground accelerations.