框架结构中越层柱考虑二阶效应的设计方法研究

Design method of multiple-story column considering second-order effect in frame structure

针对目前工程中存在的框架结构越层柱如何考虑其二阶效应的设计方法问题,以GB 50010—2002《混凝土结构设计规范》提供的基于经典结构稳定理论的二阶效应计算方法(η-l_0法)为依据,提出计算越层柱等效长度系数μ的简化计算方法——基于构件实际约束状态下的分离杆件法。经大量基于实际工程经验算例的对比与分析,总结出适用于框架结构首层越层柱取1.05,中间层越层柱取1.15,顶层越层柱取1.8的等效长度系数μ的取值建议,将μ值代入传统η-l_0法中即可方便准确地计算越层柱考虑二阶效应的内力值。经算例验证表明,文中提供的越层柱考虑二阶效应的设计方法较好地反映了框架结构中越层柱在考虑二阶效应影响下的受力规律与变形特征,可用于工程设计并为规范相关条文修订以及后续研究提供参考。

Aiming at the design problem of multiple-story columns considering the second-order effect in frame structure, based on the η-l0 method in the classical structure stability theory provided by GB 50010-2002 ‘Code for design of concrete structures’, the member isolation method under the actual constraint state for the calculation of the equivalent calculation length coefficient μ of multiple-story column has been proposed. It is concluded that the equivalent length coefficients μ are 1.05, 1.15 and 1.8 for the multiple-story columns in first story, middle story and top story of frame structures,respectively. By taking μ into the traditional η-l0 method, it is convenient and accurate to calculate the internal force value of the multiple-story column considering the second-order effect after comparison and analysis of a large number of examples based on actual engineering experience. Finally, the example calculation shows that the design method considering the second-order effect of multiple-story column can better reflects the stress law and deformation characteristics of the multiple-story column in frame structure under the influence of the second-order effect, which can be used in engineering design and provide reference for revision of the relevant provisions and the follow-up research.