负弯矩作用下考虑栓钉转动约束效应的钢-混凝土组合箱梁畸变屈曲分析

Distortional buckling analysis of steel-concrete composite box beams considering effect of stud rotational restraint under hogging moment

约束畸变屈曲是负弯矩作用下钢-混凝土组合箱梁的重要屈曲模式,其中钢梁腹板对钢梁底板的转动变形和侧向变形的约束是影响钢-混凝土组合箱梁畸变屈曲的重要因素。基于势能驻值原理,推导了腹板上边缘转动约束刚度、底板转动约束刚度和侧向约束刚度计算公式,建立了负弯矩作用下钢-混凝土组合箱梁畸变屈曲临界弯矩计算公式。基于20个算例,将本文理论计算方法与有限元数值计算方法进行了比较,结果表明:理论计算方法可以有效准确考虑栓钉、钢梁上翼缘等因素对钢梁底板的约束作用;钢梁底板转动约束刚度和侧向约束刚度均与外荷载和腹板上边缘转动约束刚度呈非线性耦合关系;在负弯矩作用下,腹板上边缘转动约束刚度对组合箱梁畸变屈曲临界弯矩有一定影响,组合箱梁畸变屈曲临界弯矩随腹板上边缘转动约束刚度的增大呈先增大后趋于稳定的趋势。

Restrained distortional buckling is an important buckling mode of steel-concrete composite box beams(SCCBB)under the hogging moment.Rotational and lateral deformation restraints of the bottom plate by the webs are essential factors affecting SCCBB distortional buckling.Based on the stationary potential energy principle,the analytical expressions for the rotational restraint stiffness(RRS)of the web upper edge as well as the RRS and the lateral restraint stiffness(LRS)of the bottom plate were derived.Also,the SCCBB critical moment formula under the hogging moment was derived.Using twenty specimens,the theoretical calculation method is compared with the finite-element method.Results indicate that the theoretical calculation method can effectively and accurately reflect the restraint effect of the studs,top steel flange,and other factors on the bottom plate.Both the RRS and the LRS have a nonlinear coupling relationship with the external loads and the RRS of the web’s upper edge.Under the hogging moment,the RRS of the web upper edge has a certain influence on the SCCBB distortional buckling critical moment.With increasing RRS of the web upper edge,the SCCBB critical moment increases at first and then tends to be stable.