基于板-梁理论的桁架拱整体稳定分析

桁架拱结构因其受力性能良好,大范围应用于桥梁及大跨度建筑结构。取桁架拱单一节间为研究对象,基于抗扭刚度等效原则,将腹杆等效为腹板。基于板-梁理论求得桁架拱节间的平面外抗弯、抗扭以及翘曲刚度。选取9个不同跨径比的桁架拱,建立有限元模型,验证了简支桁架拱在轴压和纯弯两种不同工况条件下的整体屈曲情况。轴压状态下桁架拱一阶屈曲计算承载力与有限元分析承载力平均误差1.18%,最高误差3.50%。纯弯状态下平均误差0.21%,最高误差4.54%,证明了求得的桁架拱截面等效方法及截面参数的正确性,可为工程实践提供可靠的计算方法。

Overall Stability Analysis of Truss Arch Based on Plate-Beam Theory

The truss arch structure is widely used in bridges and long-span buildings because of its good mechanical performance.Taking the single internode of truss arch as the research object,based on the equivalent principle of torsion rigidity,the web is equivalent to the plate.Based on the plate beam theory,the-out-of plane bending stiffness,torsional stiffness and warping stiffness of the truss are obtained.Nine truss arches with different span ratios are selected to establish a finite element model,which verifies the overall buckling of simple truss arches under two different conditions of axial compression and pure bending.The average error between the first-order buckling calculation and the finite element analysis is 1.18%,and the maximum error is 3.50%.In pure bending state,the average error is 0.21%,and the maximum error is 4.54%.It is proved that the equivalent method of truss arch section and the correctness of section parameters,which can provide a reliable calculation method for engineering practice.