STUDY ON SEISMIC PERFORMANCE AND COLLAPSE-RESISTANT CAPACITY OF TYPICAL FRAME-CORE TUBE STRUCTURES WITH SINGLE AND DUAL LATERAL-FORCE RESISTING SYSTEM

In the design code system of China, frame-core tube structure should be designed as a dual lateral-force resisting system, and there are strict requirements for the secondary lateral-force resisting system of such structure. In other words, the outer frame of the frame-core tube structure should have sufficient lateral stiffness and strength. However, in the design codes of other countries (e.g., ASCE-7 of the United States), the outer frame of the frame-core tube structure is permitted to only carry the vertical load. Therefore, to compare the seismic performances of the single and dual lateral-force resisting systems of the frame-core tube structure, a dual lateral-force resisting system model was firstly designed following the design codes of China. Subsequently, under the same gravity load (and the same concrete consumption), the single lateral-force resisting system model of the frame-core tube structure was design according to the following procedures:1) the secondary lateral-force resisting system was removed from the dual system, and the shear force adjustment of the frame was ignored; 2) the seismic detailing requirement of the frame was lowered to reduce the sectional size. As a result, the tube beared most of the seismic load, and the frame only resisted the vertical load. The structural responses and component damage of these two systems under SLE (Service Level Earthquake) and MCE (Maximal considered earthquake) were analyzed. Furthermore, the collapse mechanisms of two structures and their collapse-resistances were investigated. Finally, the variation of the shear force and shear distribution of the frame under different levels of earthquake and the corresponding damage of key components were discussed. The research shows that the response of the dual system structure was slightly greater than that of the single system, and their collapse resistant capacities were similar. However, the steel consumption of the single system was less than that of the dual system.