桥面铺装层刚度对简支空心板桥竖向基频的影响

Effect of Bridge Deck Pavement Stiffness on Vertical Fundamental Frequency of Simply Supported Hollow Slab Bridges

混凝土桥面铺装层对简支空心板桥竖向基频的影响主要来源于铺装层的质量和刚度贡献,其中刚度又分为纵向刚度和横向刚度。传统分析模型中一般仅考虑铺装层的质量贡献,而结构在质量相同的情况下,刚度越大、竖向基频越大。为探讨铺装层刚度对简支空心板桥竖向基频的影响,提出了3种有限元动力计算模型。通过大量的统计分析,系统研究了不同铺装层厚度对不同标准跨径的正、斜交简支空心板桥竖向基频的影响规律。结果表明:铺装层刚度对简支空心板桥的竖向基频影响显著,基频变化率在14%~29%,建议空心板桥自振频率评定时应考虑铺装层刚度贡献,否则将高估结构的受力性能。在建立动力计算模型时,正交空心板桥既可建立单板模型,也可建立梁格模型,斜交空心板桥应建立梁格模型。

The influence of concrete deck pavement on the vertical fundamental frequency of simply supported hollow slab bridges mainly includes the quality and stiffness contributions of the pavement,and this stiffness is divided into longitudinal and transverse stiffness components.The traditional analysis model only considered the quality contribution of the pavement,but the stiffness and vertical fundamental frequency of the structure increased with the same mass.In order to investigate the effects of pavement stiffness on the vertical fundamental frequencies of simply supported hollow slab bridges,three finite element dynamic calculation models were proposed.Through a large number of statistical analyses,the influence of different pavement thicknesses on the vertical fundamental frequencies of simply supported hollow slab bridges with different calculated spans were systematically studied.The results demonstrate that the pavement stiffness has a significant effect on the vertical fundamental frequency of a simply supported hollow slab bridge.The variation rate of the fundamental frequency is between 14% and 29%.It is suggested that the contribution of pavement stiffness should be taken into account when evaluating the fundamental frequency of the hollow slab bridge;otherwise,the mechanical performance of the structure will be overestimated.The influence law and degree of pavement stiffness on the vertical fundamental frequency of the orthogonal and skew hollow slab bridges are different.When building the dynamic calculation model,an orthogonal hollow slab bridge can help establish either the single slab model or the grillage model,and the skew hollow slab bridge should help establish the grillage model.