大跨度波形钢腹板连续刚构桥徐变效应研究

Creep Effect of Long-span Continuous Rigid Frame Bridge with Corrugated Steel Webs

为研究大跨度波形钢腹板连续刚构桥徐变效应,建立一座连续刚构桥有限元模型,主梁分别采用波形钢腹板箱梁与预应力混凝土箱梁,在预应力布置一致前提下对桥梁跨中与墩顶徐变变形、主梁顶底板应力及预应力损失进行对比研究。分析结果表明:预应力混凝土(Prestressed Concrete,PC)连续刚构桥中跨跨中徐变导致的挠度为波形钢腹板(Corrugated Steel Web,CSW)连续刚构桥的1.64倍,CSW连续刚构桥墩顶水平位移为PC连续刚构桥的1.21倍;在相同预应力配置下,CSW连续刚构桥顶底板徐变应力明显小于PC连续刚构桥,CSW连续刚构桥徐变预应力损失较PC预应力连续刚构桥大,说明采用CSW连续刚构对预应力损失较为不利。总体上看,采用CSW连续刚构桥梁可有效减小跨中下挠及结构应力水平,但对桥墩应力的不利影响以及预应力损失问题仍需关注。

In order to study the creep effect of the long-span continuous rigid frame bridge with corrugated steel webs,a finite element model of the continuous rigid frame bridge was established.The main girder of the bridge adopts corrugated steel webs box girder and prestressed concrete box girder.Under the premise of the same prestress arrangement,the creep deformation of the middle span and pier top,the stress of the top and bottom plate of the box girder and the prestress reinforcement loss of the bridge were compared.The results show that the deflection of prestress concrete(PC)continuous rigid frame is 1.64 times of corrugated steel web(CSW)continuous rigid frame,and the horizontal displacement of the pier top of CSW continuous rigid frame is 1.21 times of PC continuous rigid frame.Under the same prestressed reinforcement configuration,the creep stress of the top and bottom plate of CSW continuous rigid frame is less than PC continuous rigid frame significantly,and the creep prestress reinforcement loss of CSW continuous rigid frame is greater than PC continuous rigid frame,which indicates that the prestress reinforcement loss is more unfavorable for the CSW continuous rigid frame.On the whole,CSW continuous rigid frame bridge can effectively reduce the midspan deflection and structural stress level,but the adverse effect on pier stress and prestress reinforcement loss still need to be concerned.