钢桁腹式混凝土组合箱梁的挠度计算

为了研究钢桁腹式混凝土组合箱梁的挠度计算方法和影响其挠度变化的因素,将钢桁腹杆换算为具有等效厚度的换算钢腹板,对悬臂板纵向位移函数进行修正,再利用变分法原理推导综合考虑腹杆剪切变形和剪力滞效应的挠度计算公式.运用有限元软件ANSYS建立组合箱梁的有限元模型,对有限元数值计算值和理论计算值进行比较分析,并在此基础上研究高跨比和腹杆水平倾角对组合箱梁由腹杆剪切变形和剪力滞效应产生的附加挠度的影响.研究结果表明:对组合箱梁悬臂板纵向位移函数进行修正可提高挠度计算精度;对于处于合理高跨比的组合箱梁而言,其腹杆的剪切变形和剪力滞效应产生的附加挠度不可忽略;组合箱梁腹杆水平倾角仅会对腹杆剪切变形引起的附加挠度产生影响.

Deflection calculation of concrete composite box girder with steel truss webs

In order to study the calculation method of deflection for concrete composite box girder with steel truss webs and factors influencing the composite box girder′s deflection, steel truss webs are converted into steel webs with equivalent thickness, the longitudinal displacement function of cantilever plate is modified, and a formula considering steel truss webs′ shearing deformation and shear lag effect is deduced for predicting deflection by variational method. Then, a finite element model of the composite box girder is established by using the finite element software ANSYS. The numerically predicted values and theoretically calculated values are compared and analyzed respectively. On this basis, the influence of height-span ratio and the horizontal inclination angle of abdominal rod on the additional deflection produced by steel truss webs' shearing deformation and shear lag effect are both studied in details. The results show that: the accuracy of deflection calculation can be improved by modifying the longitudinal displacement function of cantilever plate of composite box girder; for composite box girder with reasonable height span ratio, the additional deflection produced by steel truss webs′ shearing deformation and shear lag effect may not be ignored; the horizontal inclination angle of abdominal rod only affects the additional deflection caused by steel truss webs′ shearing deformation.