考虑侧向约束的预应力混凝土超静定结构次内力计算及影响

由于侧向约束对超静定结构中预压力的传递以及二次内力产生的影响,有侧向约束的框架梁或连续刚构桥的预应力次内力计算比无侧向约束的连续梁次内力计算更为复杂.文中提出一种计算思路,把预加力分解为侧向约束引起的作用在柱上的预压力损失及作用在梁上有效预压力,结合等效弹簧模型及简化结构计算侧向约束预压力损失引起的次内力,利用约束次弯矩法计算有效预压力引起的次内力,然后进行叠加计算总次内力影响.通过实例分析了有侧向约束对框架结构二次内力的影响.结果表明,该影响随着梁柱刚度比减小而增大,忽略侧向约束预压力损失引起的附加二次内力影响是不合理也不安全的,文中方法能够满足工程实际中的精度要求,有助于预应力框架结构的设计和内力分析.

Calculation for secondary interior force in statically indeterminate prestressed concrete structure considering the effect of lateral restraints

Due to the transfer of compressive force and the production of secondary interior force were affected by the lateral restraints, the calculating secondary interior force for frame beam or continuous rigid frame bridge are more complicated than for the continuous beam. This paper proposed a calculation thought of calculating secondary interior force. The prestressing force was decomposed into prestress loss on the column affected by the lateral restraints and effective pre-compressed force in the beam, calculated secondary interior force caused by prestressing force with the equivalent springing model and simplify structure, using the concept of restraining secondary moment to calculate secondary interior force caused by effective pre-compressed force. The results of the examples analysis show that the effect of lateral restraints increases with the decrease of the stiffness ratio of beam-column, and it is unreasonable and unsafe neglected the third interior force induced by the prestress loss because of the effect of lateral restraints. The method proposed in this paper can fully satisfy the engineering precision is easy to be understood and is helpful to structural design and analysis for frame beam or continuous rigid frame bridge.