合龙方案对大跨PC箱梁桥成桥应力及线形的影响

Effect of Closure Scheme on Stress and Alignment of Long-span PC Box Girder Bridge

摘要:

大跨PC连续梁的合龙方案和温度等外界因素会对梁体内力分布、变形产生重要的影响。现以小清河大桥为工程背景，结合为期两周的主梁截面温度监测数据，建立空间有限元模型，研究合龙顺序、合龙温度、截面梯度温度对结构成桥应力、线形的影响。结果表明：先边跨后中跨合龙的应力分布更加平缓，所以更加合理。对于整体温度作用：合龙前升降温对结构内力影响较小。对于截面梯度温度效应：作用在中跨合龙前，对结构内力、变形影响均较大；作用在边跨合龙前，对成桥变形影响较大，但由于体系转换对成桥应力无影响。

Abstract:

The external factors of closure scheme and temperature of the long-span PC continuous girder will have an important influence on the inner force distribution and deformation of girder. Taking Xiaoqing River Bridge as the engineering background, combined with the two-week main beam cross-section temperature monitoring data, a spatial finite element model is established to study the influences of the closure sequence, closure temperature and section gradient temperature on the stress and alignment of the finished structural bridge. The results show that the stress distribution of the side span firstly and then middle-span closure is more gentle, so it is more reasonable. For the overall temperature effect, the temperature rise and fall before closure have little effect on the internal force of the structure. For the cross-sectional gradient temperature effect, its influence is large on the inner force and deformation of the structure. The influence is large on the deformation of the finished bridge before the closure of side span, but the system conversion has no effect on the stress of the finished bridge.