梯度温度对钢箱梁应力影响的测试和分析

Testing and Analysis for Impact of Gradient Temperature on Stress Acting on Steel Box Girder

本项目依托南京市某钢箱梁人行桥进行研究,对桥梁竖向不同位置的温度进行测试。建立Midas Civil有限元模型,将实桥温度数据、中英规范规定的温度作用分别模拟,相互对比,得出以下结论:尽管英国BS5400规范关于钢箱梁温度的规定已经较为详尽,但由于实际钢箱梁桥受太阳辐射、对流的温度差异实时变化明显,实际温差与规范有一定的差异。分析以双折线为代表的我国规范与以四折线为代表的英国规范的存在一定的差异,英国规范在Sbz和组合应力方面略大于我国规范。同时,钢箱梁轴向应力和Sby应力一天中随着时间的变化较小,基本维持在10 MPa之内,而Sbz的最大应力和组合应力随时间的变化波动较大,应力值介于-30~-70 MPa之间。内外弧受力存在差异与边界条件的约束能力有关。

In the study of a pedestrian bridge of steel box girder in Nanjing,the temperatures corresponding to different vertical positions of the bridge are tested,and Midas civil finite element model is built to simulate real data on the bridge temperature and compare the temperature actions specified respectively in Chinese and British codes.It is concluded that the temperature of steel box girder has been elaborately specified in British Code BS5400,but real temperature difference deviates from BS standard due to obvious real-time variation of temperature difference of the steel box girder bridge caused by solar radiation and convection.A certain differences exist between Chinese code represented by double-broken line and British code represented by four-broken line.British standard is slightly larger than Chinese standard in terms of Sbz stress and combined stress.Meanwhile,the axial stress and Sby stress of steel box girder change a little bit with time variation in a day and basically remains 10 MPa or lower.The max.Sbz stress and combined stress fluctuate greatly with time variation,and range from-30 MPa~70 MPa.Different stresses act on inner and outer arcs,is related to the restraint of boundary conditions.