整体式桥台的箱梁剪滞效应分析

Study on Shear Lag Effect for Integral Abutment and Box Girders

针对整体式桥台的箱梁固有的力学特性,建立有限元模型,对其在不同荷载作用下剪滞系数的横向和纵向分布规律进行研究,并将结果与普通简支箱梁进行比较。通过有机玻璃模型试验验证了有限元建模分析的可行性、准确性,同时作了参数分析,提出了可供工程设计参考的实用剪滞系数计算表。分析结果表明:该类箱梁剪滞分布与普通简支箱梁的不同主要在于桥台附近截面出现了负剪滞现象;整体式桥台的纵向抗弯刚度、主梁宽跨比、宽高比及不同荷载形式等是影响该类桥梁剪滞系数的主要因素。

The behavior of integal abutment and box girders （IABG） is complex and uncertain. In this paper, finite element models are established to analyze the transverse and longitudinal distribution patterns of shear lag coefficient of IABG under different loading case. Different distribution patterns of shear lag of IABG are compared with the generic bridges. The accuracy and feasibility of FEA methodis proved by the plexiglass model test. The influence of structure parameters are analysed and the practical tables calculating shear lag coefficient are provided.The results from the study show that the main difference between IABG and the generic bridges is the negative shear lag effect at the sections near abutments. It is proved that the main affecting factors of shear lag coefficients include bending stiffness, ratio of width to span, ratio of width to height, and the forms of load of abutment, etc.