Seismic Assessment and Strengthening of Intermediate Moment Resisting Concrete Frames

Abstract

The objective of this study was to investigate the seismic evaluation and strengthening of Intermediate Moment Resisting Concrete Frames (IMRCF) designed according to the Iranian concrete code of practice (ABA) and Iranian Seismic Code (Standard No. 2800).
This type of RC frames is excessively used in Iran while their vulnerability in earthquake prone area and their performance level is not clearly known for designers.
In this study, several intermediate moment resisting concrete frames have been selected and subjected to seismic evaluation according to the Iranian Guidelines for the Seismic Rehabilitation of Existing Buildings.
In this study, to determine the target point of frames, the Capacity Spectrum Method (CSM)has been used. CSM method works with capacity curves of the structural system. Such curves can be obtaining by means of static non-linear analysis (the so-called pushover analysis) that is for sure much less time-consuming than time-history analysis. The pushover analysis was performed using the SAP2000 computer program.
The results indicate that the frames having lesser spans are weak and some of structural elements are not able to fulfil the acceptance criteria given by the guidelines.
In the present paper to improve the seismic performance of such frames, one frame has been selected as a control frame and strengthened by adding different lateral load resisting systems.
The effects of proposed strengthening methods on performance of the frames have been investigated, pointing out the differences between the various strategies.