FEASIBILITY STUDY FOR A NEW STRUCTURAL SYSTEM TO RESIST THE COLLAPSE OF REINFORCED CONCRETE FRAME STRUCTURES IN EARTHQUAKES

Having collapse-resistant building structures is significant when buildings are constructed in earthquake-prone areas. For reinforced concrete (RC) moment-resisting frame structures, structural collapse generally originates from the failure of a column on the ground floor. In this paper, we propose a new girder-cable composite system that could act as a passive protection system, to improve collapse resistance of structures with a RC frame. The operating principle is presented; also, we demonstrated the application feasibility of the system using a double-span beam test. The cables were made up of high-strength, pre-stressed reinforced steel bars and they were positioned directly underneath all girders on the ground floor of the structure. Both ends of each cable were fastened to adjacent beam-column joints, which made it possible to provide large horizontal tensile forces. Originally, all cables were loose and did not come into operation before the failure of a column on the ground floor; however, the cables did start working at a threshold value with a large elongation. This elongation value was triggered due to the failure of a column on the ground floor accompanying a large deflection of the adjacent double-span girder. As a result, the load-bearing capacity that was originally provided by double-span girders was significantly improved when the girder-cable composite system was used; thus, the potential collapse of structures in a vertical direction could be prevented. The proposed system is based on a clear principle and has the advantage of providing a dramatic improvement effect on the load-bearing capacities of RC frame structures.