考虑二阶效应的混凝土桥墩弹塑性承载力理论研究与试验分析

Theoretical Research and Experimental Analysis of Elastic-Plastic Bearing Capacity of Concrete Bridge Piers Considering Second-order Effect

JTG 3362—2018《公路钢筋混凝土及预应力混凝土桥涵设计规范》计算考虑二阶效应的混凝土矩形墩柱截面承载力和配筋过程复杂且公式繁多,须先判断大小偏心再选择相应的计算公式,若采用等效矩形应力图简化计算又会带来一定的误差。针对这些问题,本文严格按照混凝土和钢筋的本构关系曲线计算其应力和内力,得到考虑二阶效应矩形桥墩对称配筋的无量纲诺模图,为工程设计提供一种简便实用的手算工具。同时,设计了钢筋混凝土偏心受压柱试验予以验证。结果表明:本文方法准确可靠,无需判断大小偏心,计算方便快捷,适用于对称配筋的任意截面尺寸和C50以下混凝土强度等级。

JTG 3362—2018 Specifications for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts has a complicated process and many formulas for calculating the bearing capacity and reinforcement of concrete rectangular piers considering the second-order effect. It is necessary to judge the eccentricity in advance,and then select the corresponding calculation formula. The use of equivalent rectangular stress diagrams to simplify the calculation will bring certain errors. In order to deal with these problems,the stress and internal force of concrete and reinforcement were calculated strictly according to the constitutive relationship curves of concrete and reinforcement,and the dimensionless nomogram of symmetrical reinforcement of rectangular pier considering the second-order effect was obtained,which provides a simple and practical manual calculation tool for engineering design. The results show that this method is accurate and reliable,does not need to judge the eccentricity in advance,and the calculation is convenient and fast. It is suitable for any section size of symmetrical reinforcement and concrete strength grade below C50.