形状记忆合金被动阻尼器及结构地震反应控制试验研究和分析

利用形状记忆合金(ShapeMemoryAlloy,简称SMA)的超弹性特性,本文提出了一种新型SMA阻尼器,将其安装在结构层间,抵抗结构地震作用。通过对阻尼器的构造设计,使其中的NiTi丝在结构振动过程中始终处于受拉状态,避免了合金丝的受压屈曲。文中首先针对一种直径为1.2mm的NiTi丝的超弹性特性进行了性能试验。试验结果表明,NiTi丝的超弹性滞回特性受其加载频率及循环圈数的影响,但当加载频率大于2Hz,加载循环圈数大于15圈后,该丝的超弹性滞回曲线趋于稳定。然后,将本文提出的SMA阻尼器安装在一个5层钢框架结构模型上进行了地震模拟振动台试验,验证了该SMA阻尼器可以有效减小结构的地震反应。最后,采用自回归(ARX)模型对无控和有控结构建模,分别采用最小二乘法和Kalman滤波法识别得到了无控结构和有控结构的ARX模型的参数,并由此进一步分析得到了无控和有控结构的各阶模态参数。

Experimental and analytical investigations of shape memory alloy as passive energy dissipation device for seismic response reduction of building

An innovative shape memory alloy(SMA) -based damper, using the pseudoelasticity of SMA wires, has been developed in this study. The SMA wire in the damper is always elongated when it is installed between the stories of a structure and subjected to earthquake excitations, and thus the buckling of the SMA wire can then be avoided. The tests were conducted to investigate the pseudoelastic property of a NiTi wire with a diameter of 1.2mm. The test results indicated that the pseudoelastic hysteresis loop of the NiTi wire is dependent on the loading frequency(<2Hz) and cyclic loading number(<15), however, independent of the loading frequency(>2Hz) and cyclic loading number(>15). Shaking table tests of a scaled 5-story steel moment-resistant frame incorporated with the SMA dampers at the first story were carried out. The test results indicated that the SMA damper can suppress structural seismic response effectively. Finally, the ARX models are employed to model the frame-damper system and the model parameters are further identified using the Least Square and Kalman Filter algorithms respectively. Furthermore, the frequency and modal damping ratio are also obtained from the ARX models of the frame with and without dampers.