Seismic collapse prevention of existing RC buildings using lightweight redundant Elements

This paper presents fast and low cost seismic retrofit technique to prevent collapse of existing RC buildings during a seismic event. The idea is to install lightweight redundant elements in specified locations in the structure to reduce inter-story drifts. These elements may be steel panels or 3D panels fabricated from polystyrene, steel, and shotcrete concrete. The steel panels are expected to works as a fuse in an electric circuit when a major earthquake occur the panels will attract the seismic forces and they may totally damaged but they will prevent sever damage in the main structural system .And the 3D panels are expected to work as a shear wall when they integer with the existing RC frame as an infill walls. The proposed panels are light-weight, easy to handle, and can be constructed very quickly. Moreover, they are cheap, and do not need formwork or skilled workers. To test the concept, shake table tests and pushover cyclic loading tests were conducted in the laboratory on half-scale, single-story reinforced concrete frame specimens. The earthquake load amplitudes were increased until a moderate damage level is reached. Then, the damaged RC frames was retrofitted by means of the steel panels or by the 3D panels and tested under the same earthquake. The seismic performance of the specimen before and after the retrofit was evaluated using FEMA356 standards, and the results were compared in terms of stiffness, strength, and deformability. The results have confirmed effectiveness of the proposed retrofit scheme.

Keywords:

Seismic , RC buildings , steel panel , 3D panel , shake table