预应力混凝土斜拉桥肋板式主梁施工过程中的剪力滞效应研究

摘要

During the construction control of pre-stressed concrete cable-stayed bridge ,the theoretical stress of the main girder will accord with the measured stress by considering shear lag effect .On the bases of the energy variation method , the finite segment method theory with two shear-lag degrees of freedom was applied during the construction control of the cable-stayed bridge .The results showed that the main girder’s cross section had both positive and negative shear lag ef-fect ,and with the increase of axial pressure in the main girder ,the negative shear lag effect would transform to the posi-tive shear lag effect .The bending shear lag coefficient of the main girder had significant change in the construction pro -cess .The research of shear lag effect not only breaks through the limitation for bridge design ,but also improves and sup-plements the theory of the construction control for long-span pre-stressed concrete bridge .%在预应力混凝土斜拉桥的施工控制中，应考虑剪力滞效应，对主梁的应力进行监测，使理论应力与实测应力更加吻合，准确判断主梁的安全状态。基于能量变分法导出每节点两剪力滞自由度的有限梁段法理论，并在某斜拉桥的施工控制中予以应用。结果表明：主梁截面既有正剪力滞效应，也有负剪力滞效应，且随着主梁内轴压力的增大，有从负剪力滞效应向正剪力滞效应变化的趋势；主梁的弯曲剪力滞系数在施工过程中变化幅度较大。在大跨度预应力混凝土桥梁的施工监控中开展剪力滞效应研究，不但突破了剪力滞理论仅应用于桥梁设计的局限性，并完善补充了桥梁施工监控的理论。