钢桁梁桥密支座体系钢桥面板高温摊铺受力分析

Mechanical Analysis of Steel Highway Deck Supported on Dense Bearings during Asphalt Placement at High Temperatures for Steel Truss Girder Bridge

公铁两用钢桁梁桥上层公路改造时常采用密支座体系钢桥面板,为选择合适的铺装方案,保证高温摊铺期结构安全,以九江长江大桥公路桥加固改造工程为背景,通过现场摊铺试验,测试高温摊铺期结构温度场;采用ANSYS软件建立钢桥面板局部模型,基于测试结果,考虑高温摊铺作用,对比分析不同摊铺分幅方案(1次整幅摊铺、分2次半幅摊铺、分4次四分幅摊铺)钢桥面板应力和支座反力。结果表明:摊铺区域钢桥面板受高温影响明显,实测顶板与底板局部最大温差为69.8℃;各分幅摊铺方案下钢桥面板均受力安全(最大应力115 MPa);仅分4次四分幅摊铺方案下全部支座符合设计要求;分幅宽度较小时钢桥面板应力和支座反力均较小。该桥采用分4次四分幅摊铺方案,结构安全,效果良好。

In this paper,the upgrading project of highway deck of Jiujiang Changjiang River Bridge is used as a case.The pavement construction methodologies after the upgrading of upper highway deck of the steel truss girder rail-cum-road bridge are compared and analyzed to ensure the safety of the steel truss girder bridge with dense bearings during the pavement construction period.Field tests were carried out to examine the temperature field in the structure during asphalt placement at high temperatures.The local finite element model of the steel deck was established by ANSYS to analyze the stresses in the steel deck plates and reaction forces of bearings in four different placement schemes,including one-off placement covering the full width of the deck,two-phase placement(half deck in each phase)and four-phase placement(a quarter deck in each phase).During the finite element analysis,the field test results and placement effect at high temperatures were counted.It is shown that the high-temperature effect on the steel deck plates in the placement zone is significant,with maximum local temperature difference in the top and base plates reached up to 69.8℃,while in the phased placement schemes,the loading condition of the steel deck was safe(the maximum stress is 115 MPa),and the four-phase placement scheme could enable the bearings to meet the design requirements.Smaller placement area would lead to relatively smller stresses in the steel deck plates and reaction forces of bearings.The four-phase placement scheme of the Jiujiang Changjiang River Bridge is proved effective,which guaranteed the safety of the structure.