矩形RC桥墩变形能力概率模型

桥墩是桥梁抗侧力体系中的关键构件。为实现基于概率和性能的桥梁抗震设计的多级性能目标,有必要给出桥墩在不同性能极限状态下的概率能力。基于已有研究工作,将RC桥墩的抗震性能水平划分为五个等级,并定义了相应的性能极限状态。采用等效集中塑性铰理论,推导并建立了各性能极限状态下RC墩柱变形能力的确定性计算公式;基于183个矩形RC墩柱试件的拟静力试验结果,通过多元回归分析,确定了各计算公式中与轴压比、长细比和配箍特征值等设计参数相关的待定系数。基于确定性计算模型和拟静力试验结果,考虑认知不确定性,建立了矩形RC墩柱变形能力的概率模型。通过实例分析,表明该模型可用于基于概率和性能的桥梁抗震设计和抗震 评估。

PROBABILISTIC DEFORMATION CAPACITY MODEL FOR RECTANGULAR RC BRIDGE COLUMNS

Piers are key components in a lateral force resisting system of bridge structures. To implement the multiple performance objectives of probability-based and performance-based seismic design for bridge structures, the probabilistic capacity of piers need to be calculated at various performance limit states. Based on previous research works, 5 seismic performance levels and 4 corresponding performance limit states are defined for RC bridge columns. The deterministic formula for deformation capacities of RC bridge columns at each performance limit state is derived from equivalent plastic hinge theory. On the basis of quasi-static test results of 183 rectangular flexure dominant RC bridge columns, the coefficients associated with the axial-load ratio, aspect ratio and stirrup characteristic value in the formula are determined by a multiple regression analysis. Considering the epistemic uncertainty of the deterministic formula, a probabilistic deformation capacity model for rectangular RC bridge columns is developed based on both the deterministic formula and the quasi-static test results. A case study for a typical RC bridge column shows that the probabilistic model can be applied to the probability-based and performance-based seismic design and the evaluation of bridge structures.