薄壁宽箱梁连续刚构桥车道荷载作用下剪力滞效应研究

Study on Shear Lag Effect of Thin-walled Wide Box Girder Continuous Rigid Frame Bridge under Lane Loading

近年来,因薄壁宽箱梁具有跨度大、质量轻、抗弯抗扭刚度大等优点在现代桥梁建设中被广泛应用,但薄壁宽箱梁却存在显著的剪力滞效应问题。因存在剪力滞效应的缺点,使宽箱梁在桥梁的设计和应用中受阻,为了得到不同车道荷载作用下剪力滞效应对薄壁宽箱梁桥的应力影响情况,文中以南圳大桥薄壁宽箱梁桥为计算实例,通过Midas/Civil 2015空间有限元软件对南圳大桥主桥进行结构分析,对薄壁宽箱梁在不同车道荷载作用下产生的剪力滞效应进行分析总结[6]。如在薄壁宽箱梁桥梁设计中忽略剪力滞效应的影响,将会漏掉箱梁腹板与翼缘板处剪力滞增加的正应力,因而导致腹板和翼缘板交接处的正应力过分集中而易造成桥梁局部破坏、失稳等问题;对实际工程中存在的的问题给出了建议,研究的结论将为今后薄壁宽箱梁的设计提供一定的参考。

In recent years, because of the advantages of large span, light quality and large bending torsional rigidity, the thinwalled box girder is widely used in modern bridge construction. However, the shear lag effect of wide box girder is a significant problem. Due to the shortcomings of shear lag effect, the wide box girders are blocked in bridge design and application. In order to obtain the influence of shear lag effect on the stress of thin-walled wide box girder bridge under different lane loads, the paper takes the thin-walled wide box girder bridge of Nanzhen Bridge as a calculation example. The structural analysis of the main bridge of Nanzhen Bridge is carried out by Midas/Civil 2015 space finite element software, and the shear lag effect of thin-walled wide box girder under different lane loads is analyzed and summarized. If the effect of shear lag is neglected in the design of thin-walled wide box girder bridges, the increase of normal stress at the web and flange slab of box girder will be omitted, which will lead to excessive concentration of normal stress at the joint of web and flange slab, and will easily lead to local failure and instability of bridges. Suggestions are given for the problems existing in practical engineering. The conclusions of the study will provide some references for the design of thin-walled wide box girders in the future.