基于高斯过程的钢-木混合结构刚度比全局敏感性分析

在钢-木混合结构中，轻木剪力墙和钢框架的刚度比是影响结构性能的重要参数。为了研究不同楼层刚度比对结构响应的影响程度，采用基于高斯随机过程的回归模型，进行了基于方差的全局敏感性分析。在分析中，建立了180个不同钢-木混合结构，以不同楼层刚度比作为影响因素，考虑了4种不同的结构响应，并以主效应和全效应作为敏感性的评价指标。结果表明，高斯过程模型对于自振周期表现出非常良好的预测能力，确定系数可达0.99以上；比较不同楼层刚度比的敏感性指标可知，当某一层结构钢框架刚度出现明显变化时，该层刚度比对结构最大层间位移角影响较大。同时，该层刚度比的全效应与主效应指标之差大于0.3，表明最大层间位移角与刚度比之间的关系具有较强的非线性特征；最大加速度对第2层刚度比最为敏感；基底剪力对各层刚度比的敏感性顺序会随地震水准的变化而改变；自振周期对结构中下部楼层刚度比更为敏感，且其全效应与主效应之差小于0.001，表明自振周期基本由刚度比的主效应决定。

Global sensitivity analysis of wall-to-frame stiffness ratio of timber-steel hybrid structure based on Gaussian-process

For the timber-steel hybrid structure, the stiffness ratio of lightweight timber shear walls over the steel frame is an important parameter which affects the seismic performance of a structure. In order to study the influence of stiffness ratios of different stories on structural response, a regression model based on Gaussian stochastic process was employed to conduct variance-based global sensitivity analysis. In the analysis, 180 different timber-steel hybrid structures were established, the stiffness ratios of various stories were treated as factors, four different structural responses were taken into account, and the main effect and the total effect were adopted as sensitivity indices. The results indicated that, the fundamental period could be predicted with excellent accuracy using the Gaussian process model, and the coefficient of determination could reach over 0.99. The stiffness ratio of a story may significantly impact the maximum inter-story drift when the stiffness of the steel frame of a story changes obviously. The difference between total effect and main effect was greater than 0.3, indicating that the relationship between the maximum inter-story drift and the stiffness ratios has the apparent nonlinear feature. The maximum acceleration was the most sensitive to the stiffness ratio of the second story. The sensitivity of the base shear to the stiffness ratios varied with the change of the seismic hazard levels. The fundamental period was more sensitive to the stiffness ratios of lower part of the structure, and the difference between total effect and main effect was less than 0.001, implying that the fundamental period was mainly governed by the main effect of stiffness ratios.