Improving The Structural Response Of Reinforced Concrete Shear Walls In Dual Systems Against Progressive Collapse

Abstract

Various structural elements in buildings subjected to unconventional loads with low probability (floods, earthquakes, explosions, etc.) which aren't considered in structural design stage. This exceptional loads may cause a local failure, which in turn causes a series of failures  and damage with an extent disproportionate to the original local damage, eventually resulting  in the collapse of an entire structure or a large part of it, especially in important buildings or high occupancy level (Schools, hospitals, trading centers…) resulting of fatalities and high repairing coasts in addition to the cessation of the building's operational function.Progressive collapse of reinforced concrete dual system (frame – shear wall) building was studied and evaluated, the building located in high seismic zone and designed according to Syrian Arab Code and it's second appendix. Based on alternative load path, in this study  partial shear wall removal (half-length of the shear wall, quarter- length of the shear wall from both sides )  from the first floor and the fourth floor (the floor where the wall section change) was investigated according to the US Department of Defense recommendations in order to improve the structural response of the building and thus its ability to transfer the additional unbalanced loads. Based on the results, the removal cases from the first floor are the most critical. As the length of the shear wall increase, the resistance against progressive collapse increases. The behavior of the shear wall improves significantly against progressive collapse by increasing the damaged shear-wall concrete compressive strength 25% and by raising the minimum vertical reinforcement ratio to 0.01 for high-strength reinforcement.