预应力混凝土连续梁桥考虑徐变时的支座沉降次内力分析

为了研究在徐变作用下，超静定结构发生支座沉降时引起的次内力，以1座5跨预应力混凝土连续梁桥为例，采用换算弹性模量法对连续梁的次内力及最终内力进行计算，在此基础上进一步分析了次内力对连续梁内力分布的影响。计算结果表明:超静定连续梁发生支座沉降时，会在结构中产生显著的次内力，在徐变作用下，由支座沉降产生的弹性内力会随时间的变化而有所减小，徐变对由支座沉降产生的弹性内力具有卸载作用，结构上的最终内力大小约为弹性内力的45%。在满足连续梁安全性的前提下，可以适当地改变截面尺寸以降低桥梁刚度，有利于节约造价，创造更大的经济效益。在实际工程中，可以采用在连续梁上施加压重或者平衡重的方式来调整结构上的内力分布，进一步降低徐变产生的次内力对桥梁结构的影响。

Analysis on Secondary Internal Force of Support Settlement of Prestressed Concrete Continuous Beam Bridge Considering Creep

In order to study the secondary internal force caused by the support settlement of statically indeterminate structure under the action of creep, taking a five-span prestressed concrete continuous beam bridge as an example, the secondary internal force and the final internal force of continuous beam are calculated by using the method of conversion elastic modulus. On this basis, the influence of the secondary internal force on the distribution of the internal force of the continuous beam is further analyzed. The results show that when the support settlement occurs in the statically indeterminate continuous beam, a significant secondary internal force will be produced in the structure. The elastic internal force generated by the support settlement will decrease with time under the action of creep. Creep has the unloading effect on the elastic internal force produced by support settlement. The final internal force on the structure is about 45% of the elastic internal force. On the premise of satisfying the safety of continuous beam, the section size can be changed properly to reduce the stiffness of the bridge, which can save the cost and create more economic benefits. In practical engineering, the internal force distribution on the structure can be adjusted by applying the pressure or balance weight on the continuous beam to further reduce the influence of the secondary internal force caused by creep on the bridge structure.