考虑纵向滑移的组合梁随机有限元可靠度分析

Stochastic finite element reliability analysis of composite beams considering longitudinal slip

针对钢-混组合梁构造复杂、材料多样、不确定性强的特点,从随机不确定性的角度来研究钢-混组合梁,基于Newmark几何模型,将钢-混组合梁的混凝土板、钢梁以及剪力连接件作为整体单元考虑,通过采用T.L列式增量法,提出并推导了考虑纵向滑移效应的非线性组合梁单元模型。结合直接微分法,对组合梁的结构响应梯度进行了计算分析;并由FORM法计算得到可靠度指标,对钢-混组合梁算例进行了随机有限元可靠度分析。计算结果表明:在实际工程中,并不需要完全刚性连接来保证结构的可靠性;在保证安全方面,考虑几何非线性来计算结构的可靠度是有必要的。

Steel-concrete composite beams are characterized by complex structure, material variety, and strong un- certainty, thus it is necessary to analyze them from the view of randomness. Based on the Newmark geometric model, considering the concrete slab, steel beams, and shear connectors as a whole element,and making use of the T.L. column incremental method, a nonlinear composite beam element model was developed by taking the longitudinal slip effect into consideration. Then, based on the model, and the characteristics of composite beams, structural response gradients of composite beams were obtained by the direct differentiation method （ DDM）, while the reliability index was achieved using the FORM method. For proof of reliability, an example steel-concrete composite beam was analyzed by the stochastic finite element program. The results show that, for practical engineering, it does not need a completely rigid connection to ensure structural reliability. However for security, it is necessary to consider geomet- ric nonlinearity in the calculation of structure reliability.