【作者】 国忠岩；

【导师】 张文元；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2007， 硕士

【摘要】 钢结构轻质高强和支撑框架水平刚度较大的特征,使得支撑钢框架在抗震设防区具有一定的应用优势。但普通支撑在大震作用下存在受压屈曲的问题,实践证明大震时支撑的反复压曲会使震害加剧。防屈曲支撑是普通支撑的改进,通过限制支撑受压屈曲,使支撑在拉压下都表现为全截面屈服。通过合理的设计,可以使防屈曲支撑在罕遇地震发生时能够率先屈服,利用其滞回行为消耗地震输入能量,保护主体框架结构。本文首先对防屈曲支撑构件进行了简单的理论分析,给出了支撑受轴力时内核单元全截面屈服发生在整体失稳和自身失稳之前的条件、内核单元与约束单元之间间隙的确定方法。分别对普通中心支撑框架结构、采用与普通中心支撑框架结构相同支撑截面面积的防屈曲中心支撑框架结构、采用减小支撑截面面积的防屈曲中心支撑框架结构、采用低屈服点钢材的防屈曲中心支撑框架结构四类模型进行了大震时程分析。发现采用与普通支撑面积相等的防屈曲支撑,结构响应变化不明显;采用减小面积的防屈曲支撑,顶层绝对加速度峰值、层剪力和底部剪力峰值都有所减小,而结构的位移响应比较接近;采用低屈服点钢材的防屈曲支撑,不仅解决了支撑杆件的失稳问题,而且减小了结构位移等响应。对比了梁柱铰接时上述支撑框架结构在大震下的时程响应。发现采用与普通支撑面积相等的防屈曲支撑,结构位移响应略有减小;采用减小面积的防屈曲支撑,顶层绝对加速度峰值、层剪力和底部剪力峰值都有所减小,而结构位移响应仍然比较接近;采用低屈服点钢材的防屈曲支撑,不仅解决了支撑杆件的失稳问题,而且减小了结构位移等响应。结合大唐长山热电厂主厂房支撑框架结构,对比了采用普通支撑和防屈曲支撑时的弹塑性动力时程响应。发现采用防屈曲支撑可以避免支撑杆件失稳,支撑在受压时各项动力响应都有所减小,优势明显,但在受拉时这种优势并不明显,而且支撑采用低屈服点钢材时进入塑性较早还可能增大结构侧移。更多还原

【Abstract】 The steel structure is light-weight and high-strength , and braced frame has good lateral load stiffness ,these advantages make braced frame play a important role in the seismic zone. However, common brace will buckle under big earthquakes. Diagonal and V-shape concentric braces were ever popular in seismic regions, but actuality convinced that the degradation of such braces in stiffness and strength caused by buckling aggravated the damage to the steel frames under severe earthquakes.The Buckling-Restrained Brace (BRB) is a new brace compared to common brace. The compression and tension loads are designed to be carried only by the core by means of unbounded layer to allow the free slip between the core and the surrounding concrete. The BRB can reach and retain fully sectional yielding of the core under compression, and exhibits stable hysteretic behavior when cyclically loaded.This text first simply analyzed the theory of the Buckling-Restrained Brace,deduced the formula of fully sectional yielding of the core before buckling that when BRB was carried to axial force, and the clearance between the central steel core and restriction part.By analyzing the time-history of the followed four models: common central braced frame, central braced frame using BRB with the same area, central braced frame using BRB with smaller area, central braced frame using BRB with low yield point steel on big earthquake ,we find that using BRB with the same area of common brace, the change of responses of construction was little ;if using BRB with smaller area,peak values of absolute acceleration of top floor and bottom shear all became smaller, but the change of displacement response of construction was also little; using BRB with low yield point steel, can not only solved the problem of buckling, but also all decreased displacement response.By comparing the time-history response of hinge braced frame structure under big earthquake we find that if using BRB with the same area of common brace, the responses of construction changed a little smaller;if using BRB with smaller area,peak values of absolute acceleration of top floor and bottom shear all became smaller, but the change of displacement response of construction was also little; if using BRB with low yield point steel, can not only solve the problem of buckling, protracted fatigue damages life ,but also decrease all responses of construction especially displacement response.Combining with main frame of CHANGSAN power house ,we did some comparison on the time-history response of the common brace and BRB, and find that the plastic dynamic analysis of BRB frame showed that BRB could solve the problem of buckling, under press force all responses of construction became smaller but under pull force the change was not obvious,and that the lateral displacement maybe become larger due to low yield point.更多还原