下穿铁路斜交框架地道桥主要设计参数分析

为了研究设计参数对铁路斜交框架地道桥受力特性的影响,依托某实际工程,建立数值模型进行分析。以原结构为基础,分别改变框架地道桥的宽跨比、斜交角、高跨比、腋角尺寸并分别建立有限元模型计算分析,研究设计参数增长15%时受力特性的变化规律。并设计正交试验以找出参数的影响程度及优化方案。研究结果表明:设计参数变化时,结构受力的变化规律相似,但受力特性的影响程度不同;宽跨比、高跨比、腋角尺寸的增加可使顶板主拉应力减小;宽跨比、腋角尺寸的增加可使顶板竖向位移减小;在4个设计参数中高跨比对顶板主拉应力的影响最大;提出的优化方案与原结构相比,可使顶板在单列车荷载下最大主拉应力降低35.4%、在双列车荷载下最大主拉应力降低45.7%。

Analysis of Main Design Parameters for Skew Frame Underpass Bridge under Railway

In order to study the influence of design parameters on the mechanical properties of skew frame underpass bridges, a numerical model is established for analysis with reference to a practical project. Based on the original structure, the width-to-span ratio, skew angle, high-to-span ratio and axillary angle size of the frame underpass bridge are changed respectively, and finite element models are established for calculation and analysis to study the variation of the mechanical behavior of the frame bridge when the design parameters are increased by 15%. Orthogonal experiments are designed to find out the degree of influence of parameters and the optimization scheme of structure. Calculation results show that: when working conditions and design parameters are changed, the change laws of the mechanical performances are similar, but the degrees of influence of the mechanical performances are different. The increase of width-to-span ratio, high-to-span ratio and the size of the axillary angle can reduce the principal tensile stress on the roof. The vertical displacement of roof can be reduced by increasing the width-to-span ratio and the size of the axillary angle. Among the four design parameters, the high-to-span ratio has the greatest influence on the principal tensile stress on the roof. Compared with the original structure, the proposed optimization scheme can reduce the maximum principal tensile stress on the roof by 35.4% under single-train load and 45.7% under double-train load.