大跨径混凝土梁桥设计新思路

以大跨径预应力混凝土梁桥存在开裂、下挠过大等病害为对象,研究病害的主要成因和对策,试图探讨解决这些问题的设计新思路,即引入斜拉桥施工监控原理,对影响其应力、位移的主要因素,即自重、预应力摩阻损失、混凝土收缩徐变等进行施工和使用阶段的监控,并根据参数识别在施工阶段对预应力束进行股数调整,在使用阶段利用体内和体外备用束视监控情况进行内力调整,从而提高梁体的抗裂性能,达到有效预防混凝土梁桥常见的梁体开裂、跨中下挠过大等病害,文中对珠江大桥的设计做了简单介绍。

A New Concept of Designing Long Span Concrete Beam Bridge

Main causes of crack and large deflection on long span concrete beam bridges are studied and a new concept to account for them is discussed.The theory of cable-stayed bridge construction monitoring is applied to prestressed concrete beam bridge.Controlling stress and displacement of bridge caused by dead weight,attrition loss of prestress wire,creep and shrinkage of concrete,temperature effect and foundation settlement etc.are analyzed during the construction stage and operation stage.The number of prestress wires are adjusted based on parameter identification during construction,and the spare internal tendons and external tendons are modified according to internal force on operation.By these measures,the prevent cracks of girder and undue deflection at midspan of long span prestressed concrete beam bridge could be prevented.At the same time,the design principle of the Zhujiang River Bridge is briefly introduced.