曲线梁独塔斜拉桥的抗震分析模型探讨

Discussion on Finite Element Models for Seismic Analysis of a Curved Cable-Stayed Bridge with Single Pylon

以东平水道大桥为工程背景,比较了按弯梁原始线形建立的曲梁模型和按以直代弯方式建立的直梁模型在结构动力特性、地震响应等方面的差异,讨论斜拉弯桥有限元简化建模的可能性,并通过改变主梁的弯曲圆心角探讨直梁模型的适用性。分析表明,采用以直代弯建模对结构的主要振型周期、模态和质量参与系数不会产生明显误差;非线性时程分析结果也肯定了直梁模型的数值精度;主梁弯曲圆心角的增大则会削弱直梁模型的适用性。误差分析结果显示,直梁建模方式对一般桥梁结构的抗震设计具有足够的可信度。

Based on the Dongping Channel Bridge,two finite element models（FEMs） were established,i.e.a straight model neglecting the spatial shape of the curved deck and using straight geometry instead,and a curved model according to the original shape of the deck.Comparison between these two FEMs in both structural dynamical characteristics and seismic response was conducted to discuss the possibility of simplifying the seismic analytical model.Furthermore,applicability of the straight model was assessed through varying the central angle of the curved deck.The results show that the straight model will not cause unacceptable errors in main periods,mode characteristics and modal participating mass ratios.The time history analytical results obtained from the straight model are proved to be credible.Increase in the central angle will impair the applicability of the straight model.Error analysis tells that the straight model is sufficiently accurate in seismic analysis and can be applied in the practical seismic bridge design.