Research On The Enhance Of The Limited Stiffness Belted-outrigger To The Frame-Core Tube Structure

Because the whole lateral stiffness can not match the design standard, the frame—tube structure can not reach the limitation of displacement in the wind loads or seismic forces according to the national standards. In order to improve the whole lateral stiffness, the rigid outriggers are usually set in the refuge story and facility story to enhance the relations between the tube and the outer columns.The high—rise buildings with rigid outriggers are generally used. Based on analyzing the engineering information, it is known that most of the building structures control the level of displacement by the rigid outriggers, but the rigid outriggers will result in the sharply variation of the structural stiffness and internal forces under the power of earthquake. The yield mechanism will be difficultly realized as "strong column, weak beam" and "strong in resistance of shear force, weak in resistance of bending moment" under the seismic forces, so the rigid outriggers are usually used in the non—seism regions. Due to the influence of Wenchuan Earthquake, the frame—tube structure with rigid outriggers will have negative behavior under the seismic force in Chengdu. Therefore, the research should not only focus on the rigid outriggers, and further studying should be developed.In view of the current study focused on the rigid outriggers, this paper discussed the influence to internal force when two different outrigger ware set in the structure under the seismic force, after studying the seismic reaction of the rigid outrigger and the limited rigidness outriggers. And it tried to discuss whether the limited rigidness outriggers took place of the rigid outrigger to solve the problems that the concentrated rigidity resulted in the sharply variation of internal force.The FEA analysis software SAP2000 is applied to analyze the frame—tube structure with seven different outriggers under the seismic force. Through comparing the differences, which includes the seismic response of period, displacement and internal forces between the rigid outriggers and the limited rigidness outriggers. This paper also discussed how to take measures to reduce the adverse influence of the seismic force in the higher intensive earthquake—proof region because of the sharply variation of the rigidity in the structure.