地震波特性对形状记忆合金自复位支撑框架响应影响

INFLUENCE OF SEISMIC WAVE CHARACTERISTICS ON THE RESPONSE OF SELF-CENTERING BRACED FRAME WITH SHAPE MEMORY ALLOY

地震作用下屈曲约束支撑框架具有较好的消能减震效果,但是支撑进入塑性后残余变形较大,影响了框架震后可修复。将形状记忆合金(SMA)与屈曲约束支撑(BRB)组合,形成了SMA自复位屈曲约束支撑(SMA-SCBRB)。为了对比普通屈曲约束支撑(BRB框架)和SMA自复位屈曲约束支撑框架(SMA-SCBRB框架)的动力特性,基于已开展的足尺振动台试验模型,选用了6条近场地震波和4条远场地震波作为地震动输入,对比两类框架的动力反应。结果表明:BRB框架结构具有较好的消能减震效果,近场地震波作用下,BRB框架的顶点位移、顶点残余位移、层间位移角和层间残余位移角均大于远场地震波作用下的结构反应;将框架中的BRB按照"等屈服力原则"替换为SMA-SCBRB,近场和远场地震波作用下BRB框架和SMA-SCBRB框架有着相近的顶点位移和层间位移角,能够保证SMA-SCBRB通过轴向变形充分耗能;BRB框架具有较大的顶点残余位移和层间残余位移角,近场地震波作用下残余变形更大;而相应的SMA-SCBRB框架的残余变形降低,特别是下部楼层降低得更为显著,且SMA-SCBRB框架各层的层间残余位移角相近,对结构震后修复更为有利。

Buckling-restrained braced frame(BRBF) shows an excellent energy dissipation capacity under earthquake action event, but BRBF has a large residual deformation after the brace enters its plastic state, reducing the reparability of energy dissipation capacity BRBF after earthquake. The self-centering buckling-restrained brace(BRB) with shape memory alloy(SMA) and composed of self-centering brace and SMA shape memory alloy(SMA-SCBRB) was proposed. To compare the dynamic characteristics of BRBF and the self-centering buckling-restrained braced frame(SMA-SCBRBF), numerical models were established based on a full-scale shaking table test structure, and six near-field seismic waves and four far-field seismic waves were selected as the seismic excitation. The numerical results showed that: 1)BRBF had an excellent, and the top displacement, the residual top displacement, the story drift and the residual story drift of the BRBF under the near-field seismic excitation were greater than those under the far-field seismic excitation;2) SMA-SCBRBF, which replaced the BRB in the frame based on the principle of "equivalent yield force", showed a similar top displacement and story drift with BRBF under both the near-field and far-field seismic excitations, including the excellent energy dissipation capacity. 3)BRBF exhibited large residual roof displacement and story drift, and the residual deformation of the BRBF under near-field seismic excitation was larger than those under far-field seismic excitation. 4)SMA-SCBRBF showed a reduction on the residual deformation compared with BRBF, and the reduction at the lower floor was more significant than that at the upper floor;moreover, the residual story drifts of the SMA-SCBRBF at each story were nearly equal, which could improve the reparability of the structure after an earthquake action.