无侧移变轴力框架柱稳定性的等效力法  

EQUIVALENT FORCE METHOD FOR THE STABILITY OF NON-SWAY FRAME COLUMN WITH VARYING AXIAL FORCE

作　　者：田炜烽[1] 郝际平[1] 樊春雷[1] 吴元莅[1] 

机构地区：[1]西安建筑科技大学土木工程学院,西安710055

出　　处：《工程力学》2012年第11期212-220,共9页Engineering Mechanics

基　　金：国家自然科学基金项目(50878181);陕西省自然科学基金青年基金项目(2010JQ7001);陕西省教育厅专项科研项目(2010JK630)

摘　　要：该文根据无侧移压杆的屈曲形态提出了以轴力对压杆跨中抗侧刚度的削弱来表征轴力负刚度的力学模型,并利用该模型阐释了无侧移框架计算长度系数的力学意义。在该模型的基础上,根据等效负刚度相等的原则,建立了无侧移框架柱中力与柱顶力之间的等效关系,推导了等效力系数的计算公式。通过该系数,可以将柱中力折算到柱顶,并直接通过规范查取计算长度系数验算框架柱的整体稳定,而不需要重新对计算长度系数进行折算。进一步提出了等效力法,该方法可以很好的解决无侧移框架柱的变多次轴力问题,具有很好的精度。算例计算结果表明:等效力法具有很好的精度和准确性,可供工程设计及理论计算使用。According to the buckling behavior of compression members, this paper propose a mechanical model, which use the weakening to the midspan lateral stiffness of the compression member by axial force to characterize the axial force＇s negative stiffness. By this model, the mechanical meaning of the effective length for non-sway frame was elaborated. Based on this model and the principle of equal equivalent negative stiffness, the equivalent relationship between the top load and the intermediate load acting on a frame column was established, and then the equivalent load factor formula was derived. Through this factor, an intermediate load can be converted to a top load, so that the stability of a frame can be checked by the effective length gained from Code, without recomputation. Then, the equivalent force method is proposed. This method can solve the stability problem of a non-sway frame under multiple-varying axial force easily with a good accuracy, thusly it can meet the requirements of engineering applications. The results show that the equivalent force method can be used for engineering design and theoretical calculations with good precision and accuracy.

关 键 词：稳定 等效力法 无侧移框架 变轴力 负刚度 

分 类 号：TU311.2[建筑科学—结构工程] TU318.2