The Research On Seismic Performance Of Steel Frame-concrete Core Tube Structures With Eccentrically Braces

Steel frame-concrete core tube structure system has been rapidly developed in recent years in china and has aroused widespread concern of investors and industrial circles,because of its obvious advantages such as reduction of self-weight and cross-section size, and speeding up the construction progress. At present there are few studies on the seismic properties of the structure in abroad, neither at home. because strength and ductility of the inner core tube are inadequate and stiffness relatively more than needed, however stiffness of steel frame is relatively not enough and strength and ductility adequate, as a result, the seismic performance of steel frame and concrete core tube lacks of coordination, which they neither reasonably contribute to earthquake nor form double side resistance system. Eccentrically braces have never been considered in the system at present, but additional eccentrically braces were considered in the steel framework in this paper.In this paper, additional several parallel out eccentrically braces and cap connection or waist connection eccentrically braces are considered in the high-rise structure system. So the analysis of seismic response properties of the system for three models such as without braces, with eccentrically braces and with eccentrically braces changed in the location and number has been carried out through structural analysis and design software ETABS plus C Chinese version 9.0.0. According to"high-rise building concrete structures technical code"(JGJ3-2002 / J186-2002) on the analysis of the structural calculations, firstly, vibration mode decomposition spectrum of the structure was carried out on the analysis of the natural vibration period, the displacement, inter-story drift angle, ratio of overturning moment, total shear for each floor, total moment for each floor, the shear undertaken by steel framework and shear adjustment factor and other indicators. Secondly, additional analysis was studied through flexible time-analysis of the structure under four different seismic waves on the envelope diagram of max inter-story drift angle and max story displacement curve, the envelope diagram of total shear and total moment curve and of the largest floor acceleration curve.In short, the seismic performance of the structure with eccentrically braces was analyzed and evaluated, and some recommendations are gived for further study.