高强轻质混凝土连续刚构桥箱梁长期变形分析

为探明局部使用高强轻质混凝土对连续刚构桥上部箱梁长期挠度带来的影响,根据一座预应力高强轻质混凝土连续刚构弯梁桥的结构特点,采用有限元理论对该桥在不同荷载长期作用下箱梁竖向挠度的时变效应进行了空间计算和分析,并与相同结构尺寸的普通混凝土连续刚构桥在同工况下的长期变形效应进行了对比。恒载作用下,应用高强轻质混凝土的大跨径连续刚构桥,成桥五年后主跨跨中挠度可较普通混凝土桥减小;持载时间对应用高强轻质混凝土的连续刚构桥后期挠度较普通混凝土桥减小程度影响较大,荷载作用时间愈长,后期挠度减小幅度愈大;高强轻质混凝土的长期性能对局部使用高强轻质混凝土连续刚构桥的长期变形有重要影响。所得分析结果,对指导高强轻质混凝土桥梁的设计具有理论意义和工程实用价值。

Analysis on Long-term Deflection of High Strength Light-weight Concrete Box Beams of Continuous Rigid Frame Bridges

In order to explone up what influences long-term deflection of box girder on continuous rigid frame bridge with partly using high strength light-weight concrete,based on the structure design characteristic of a three-span prestressed light-weight concrete continuous rigid frame bridge,spatial calculation and analysis with FEA theories were carried out on long-term deflection of the box girder subjected to the permanent load and focus load.Deflections of box girder on continuous rigid frame bridge were calculated in different loadings.Conclusions are drawn as following:(1) Under the permanent load,deflection of middle stride of the continuous rigid frame bridge could be effectively decreased five years after the bridge being made up with the application of high strength light-weight concrete,which could be 20% less than the same structure of common concrete bridge;(2) There is obvious influence on decreasing degree of the upper deflection with the lasting time of the load.The longer the load lasts,the more decreasing degree of the upper deflection will be;(3)Long-term capability of high strength light-weight concrete operates importantly on the long-term deflection of continuous rigid frame bridge which made partly by high strength light-weight concrete.All the above gives a reference to light-weight concrete bridge design.