大跨度连续刚构桥受力影响机理及控制策略研究

Research on Force Influence Mechanism and Control Strategy of Long-span Continuous Rigid Frame Bridge

摘要:

为探究大跨度连续刚构桥挠度及内力影响机理和控制策略问题，首先对主梁下挠成因进行了简要分析，并结合分析结果，给出了用于后续计算分析的计算工况和有限元模型；其次探究了主要影响因素对连续刚构桥挠度和内力的影响机理；最后基于影响机理分析结果，提出了减小主梁下挠和内力的控制策略。研究表明，影响大跨度预应力混凝土连续刚构桥主梁竖向挠度以及结构受力的主要因素有：相对湿度、加载龄期和预应力损失，其中影响程度从大到小的顺序为预应力损失＞相对湿度＞加载龄期；当预应力损失从5%变化到25%时，主梁竖向挠度最大约增加了18.86%，主梁弯矩约是原来的2倍，可见预应力损失会显著加大主梁的弯矩和主梁竖向挠度；为防治大跨度预应力连续刚构桥在营运过程中出现较大程度的下挠和内力问题，有必要从设计阶段、施工阶段以及营运阶段对预应力损失进行控制。

Abstract:

In order to explore the influence mechanism and control strategy of deflection and internal force of long-span continuous rigid-frame bridge, the causes of main beam deflection are briefly analyzed at first, and combined with the analysis results, the calculation conditions and the finite element model for the subsequent calculation and analysis are given. Secondly, the influence mechanism of main influencing factors on the deflection and internal force of continuous rigid frame bridge is explored. Finally, based on the analysis results of the influence mechanism, the control strategy to reduce the deflection and internal force of the main beam is proposed. The research shows that the main factors affecting the vertical deflection of the main beam and the structural force of the long-span prestressed concrete continuous rigid-frame bridge are the relative humidity, loading age and prestressing loss, in which the order of the degree of influence from large to small is the prestressing loss, relative humidity and loading age. When the prestressing loss changes from 5% to 25%, the vertical deflection of the main beam increases by 18.86% in maximum, and the bending moment of the main beam is about 2 times of the original, which can be seen that the prestressing loss will significantly increase the bending moment and vertical deflection of the main beam. In order to prevent the large-span prestressed continuous rigid-frame bridge from the lower deflection and internal force problems during the operation, it is necessary to control the prestressing loss in the design stage, construction stage and operation stage.