摩擦耗能型SMA杆自复位梁柱节点滞回性能分析

在梁柱节点中引入NAO（非石棉）摩擦耗能器和超弹性形状记忆合金（SMA）杆，形成摩擦耗能型SMA杆自复位梁柱节点（NAO-SMA-SC），可有效解决传统梁柱节点震后残余变形较大和耗能较低的问题。该文分析了其构造和工作机理，针对节点中SMA杆大应变需求，基于Lagoudas模型提出SMA杆的应变强化段改进本构模型，并将其嵌入到有限元软件OpenSees；建立了NAO-SMA-SC节点的杆系分析模型，考察了循环加载机制下SMA杆、NAO摩擦耗能器、间隙单元随节点转动时的受力行为；系统分析了耗能器摩擦力F_f、SMA杆直径D、SMA杆预应变P等关键参数对NAO-SMA-SC节点滞回性能的影响。结果表明:在节点中引入摩擦耗能器，能明显地提高节点抗弯能力和耗能能力，但同时会增大节点残余变形；随着SMA杆直径的增大，节点抗弯能力和自复位性能均显著提高；SMA杆预应变的施加能有效降低节点的残余变形。

HYSTERETIC PERFORMANCE ANALYSIS OF SELF-CENTERING BEAM-COLUMN CONNECTIONS WITH SMA BARS AND FRICTION ENERGY DISSIPATOR

By introducing NAO (non-asbestos organic material) friction energy dissipator and superelastic SMA (Shape Memory Alloy) bars into beam-column connections, a self-centering connection with friction devices (NAO-SMA-SC) was proposed, effectively dealing with both the large residual drift and the lower energy dissipation of traditional connections after earthquake. In this paper, the details and working mechanism were analyzed. Due to the large strain demand of SMA bars, based on the Lagoudas model, a strain-hardening modified model of SMA bars was presented. Adding the proposed model to the finite element software OpenSees, the analysis model of NAO-SMA-SC connections was developed to study the mechanical behavior of SMA bars, NAO friction devices and gap element during the rotation of connections under the cyclic loading condition. The influences of several key parameters, including the friction force F_f, the diameter D and initial strain P of SMA bars, on the hysteretic performance of NAO-SMA-SC connections were analyzed systematically. The results show that the friction device could significantly improve the resisting moment and energy dissipation ability of connections, meanwhile increase the residual drift. The enlargement of SMA diameter could promote the moment and self-centering effect of connections. Pre-stressing the SMA bars could effectively reduce the residual drift of connections.