带耗能框架的框排架混合结构受力特性及抗震设计方法

Mechanical feature and seismic design method of frame-bent hybrid structure with energy-dissipating frame

传统框排架结构的质量和刚度分布往往不均匀,在强烈地震作用下易发生薄弱部位的损坏且震后很难修复。文中对该类结构进行改进提出一种带耗能框架的框排架混合结构体系,以实现地震作用下的构件集中耗能及震后耗能构件可更换。阐述了所提结构体系的组成、工作机理和预期破坏模式。利用SAP2000对11榀框排架混合结构进行非线性静力分析,研究可更换梁的破坏模式、是否层间布置和耗能框架位置等参数对框排架混合结构受力特性的影响,而后对结构的耗能能力进行了分析。结果表明:该框排架混合结构能够实现预期的破坏模式和受力状态,“剪切型”可更换梁承载力和刚度更高且利于更换,耗能框架层间布置可更换梁并提高整体结构的承载力,不同位置布置耗能框架对整体结构的承载力和刚度影响不大,可更换梁选用“剪切型”、窄翼缘,结构的耗能能力较好。对框排架混合结构进一步进行动力时程分析和非线性静力分析,提出了基于性能的两阶段抗震设计方法。弹性阶段以耗能框架和框排架的弹性刚度比(KDF/KMF)以及可更换梁和框架梁的屈服位移容差(Δ2/Δ1)作为抗震设计的控制参数,弹塑性阶段以结构中塑性铰的分布和不同性能水准下框排架混合结构的层间位移角限值为控制指标。通过计算分析,给出了弹性刚度比、屈服位移容差和层间位移角限值的取值范围。算例分析表明:当耗能框架的剪力占比为25%~45%,弹性刚度比为0.4~0.9,屈服位移容差不小于1.3时,结构具有较好的可更换性,所提出的基于性能的两阶段抗震设计方法是可行的。

The mass and stiffness distribution of the traditional frame bent structure are often uneven. It is easy to damage the weak parts under the action of strong earthquake,and it is difficult to repair after the earthquake. In this paper,a frame bent hybrid structure system with energy dissipation frame is proposed to improve this kind of structure,so as to realize the centralized energy dissipation of members under earthquake and the replaceable energy dissipation members after earthquake. The composition,working mechanism and expected failure mode of the proposed structural system are described. Using SAP2000,the nonlinear static analysis of 11 frame bent hybrid structures is carried out,and the effects of failure mode of replaceable beams,interlayer layout and energy dissipation frame position on the mechanical characteristics of hybrid structures are studied and then the energy dissipation capacity of the structure was analyzed. The results show that the frame-bent hybrid structure can achieve the expected failure mode and stress state,the "shear-type" replaceable beam has higher bearing capacity and stiffness and is easy to replace,and the replaceable beams arranged between the layers of the energy-consuming frame can improve the overall performance. The bearing capacity of the structure,the arrangement of energy dissipation frames in different positions has little effect on the bearing capacity and stiffness of the overall structure,and the replaceable beams use "shear type" and narrow flanges,and the energy dissipation capacity of the structure is better. The dynamic time history analysis and nonlinear static analysis of frame bent hybrid structure are further carried out,and a two-stage seismic design method based on performance is proposed. In the elastic stage,the elastic stiffness ratio(KDF/KMF)of energy dissipation frame and frame bent and the yield displacement tolerance(Δ2/Δ1)of replaceable beam and frame beam are taken as the control parameters of seismic design. In the elastic-plastic stage,the distribution of plastic hinges in the structure and the limit value of inter story displacement angle of frame bent hybrid structure under different performance levels are taken as the control indexes. Through calculation and analysis,the value ranges of elastic stiffness ratio,yield displacement tolerance and interlayer displacement angle are given. The example analysis shows that when the shear ratio of energy dissipation frame is 25%~45%,the elastic stiffness ratio is0.4~0.9,and the yield displacement tolerance is not less than 1.3,the structure has good replaceability,and the proposed two-stage seismic design method based on performance is feasible.