Evaluation of Seismic Retrofitting Techniques Used in Old Reinforced Concrete Buildings

Abstract

Past earthquakes have emphasized the vulnerability of existing structures which did not satisfy modern seismic design requirements and current engineering standards even though they may have been properly designed and constructed according to earlier codes. Many existing buildings may be inadequate and pose severe risk during seismic events. To mitigate the seismic hazard, existing building should be rehabilitated. The rehabilitation measures to upgrade the capacity of these structures can be performed at some point in their useful lives. The evaluation of the seismic capacity of existing buildings and their deficiencies is essential for the design of a rehabilitation technique. The aim of the evaluation and rehabilitation systems is either for collapse prevention to ensure safety of the occupants or to control the damage to ensure the continuity of operation during and after earthquakes. In this paper several retrofit techniques was evaluated by applicable them on different kinds of existing structures to find the best one will be used for each kind of tested structures. Four retrofit techniques (R.C. walls, steel bracing, column jacket, and column strengthen by 4 steel angles each corner) were tested for each selected four existing structure. By examine each technique on each tested structure, the values of top displacement, top floor acceleration, max. base shear, and period time of first mode were varied by response of each applied retrofit techniques and the minimum response will be the choose as arbitrator between different kinds of used techniques to use it as the optimal technique used to retrofit this structure.