Real-Time Hybrid Simulation of Shape Memory Alloy Dampers

随着经济技术要求的不断提高，采用传统的建筑材料进行土木工程结构抗震设计已不可能。形状记忆合金（SMA）是一种具有独特特性的金属智能材料。在没有任何残余伸长的情况下，sma在机械应力引起的大变形甚至超过7%的应变后也能恢复到原来的形状。这种所谓的超弹性性能使SMA成为现有阻尼系统的一个有吸引力的替代方案，现有阻尼系统显示出显着的技术局限性。传统的抗震装置如金属钢阻尼器，由于其不可恢复的塑性变形，每次强烈的地震激励后都需要更换，这是一个代表性的例子。为了使基于SMA的阻尼器得到更广泛的应用，需要在数值和实验方面进行进一步的研究。到目前为止，研究人员对sma能量耗散能力的变化过程发现了不一致和部分不同的结果。在实验部分，缺少配备SMA阻尼器的全尺寸振动台试验。在数值部分，现有的本构模型有待改进。这些研究揭示了SMA钢丝在地震反应方面的显著差异。频率效应和应变幅值的相互作用以及地震荷载独特的瞬态特性被认为是现有模型不准确的原因。在提出的项目中，使用实时混合模拟（RTHS）分析了SMA阻尼器的地震性能。因此，该结构被划分为物理子结构和数值子结构。RTHS提供了一个全尺寸的实验解决方案，通过数值模拟受控结构，同时测试阻尼器的实验。此外，该研究项目旨在通过区分循环加载效应（即SMA在重复加载条件下的行为）和瞬态地震加载效应（即地震加载的随机性），改进SMA动力响应的现有本构模型。

Increasing economical and technical requirements make the design of earthquake resistant civil engineering structures with traditional construction materials impossible. Shape memory alloys (SMA) are metallic smart materials with unique characteristics. Without any residual elongation, SMAs can recover their original shape after mechanical stress induced large deformations with even over 7 % strain. This so-called superelastic behaviour make SMA an attractive alternative to the existing damper systems, which show significant technical limitations. Conventional anti-seismic devices such as metallic steel dampers, which need to be replaced after each strong seismic excitation because of the non-recoverable plastic deformation, count as a representative example.A broader application of the SMA based dampers require further research both on the numerical and experimental part. Until now, researchers identified inconsistent and partly different results regarding the change process of the energy dissipation capacity of the SMAs. On the experimental part, full-scale shaking table tests with SMA damper are missing. On the numerical part, the existing constitutive models need to be improved. The studies revealed significant discrepancies regarding the seismic response of the SMA wires. The interaction of both the frequency effects and the strain amplitude together with the unique transient character of the earthquake loading are supposed to be the reasons for the inaccuracy of the existing models. In the proposed project, the seismic behaviour of SMA dampers using real-time hybrid simulations (RTHS) is analysed. Therefor the structure is partitioned into into physical and numerical substructures. RTHS provides a fullscale experimental solution by simulating controlled structures numerically while testing dampers experimentally.Furthermore, the research project aims to improve the existing constitutive models regarding the dynamic response of the SMA by differentiating between cyclic loading effects, meaning SMA behaviour under repeated loading conditions, and transient earthquake loading effects regarding the stochastic nature of seismic loading.