配体外预应力钢束的曲线箱梁桥抗扭设计

为了抵抗曲线箱梁桥的扭转效应、改善结构的受力状态,在不增加预应力钢束数量的前提下,提出一种利用体外预应力钢束形成空间抗扭作用的方法.基于空间解析几何关系推导了体外预应力扭矩计算公式,以此建立了以最小扭矩为目标的体外预应力钢束的抗扭设计流程,并利用非线性规划方法给出钢束最优平面线形参数的数值解法.分析结果表明,与体内预应力钢束相比,通过合理的体外预应力钢束空间布置,能大幅降低扭矩峰值,抗扭效果明显,且不影响抗弯、抗剪能力;扭矩计算数值解与有限元分析结果吻合良好,能方便地用于实际设计.

Torsion resistant Design in Curved Box girder Bridges with External Tendons

In order to resist torsion effect to improve the stress state in curved box girder bridges, the torsion resistant design method of applying external tendons without increasing tendons is proposed. Based on the space analytic geometry relationship, the externally prestressing torsion calculation formulas are derived out. The torsion resistant design process of applying external tendons is presented with the objective of minimizing torsion. The optimal parameters of horizontal alignment of tendons are solved with non linear optimization method at the end of the process. The results indicate that the reasonable space layout design of external tendons instead of internal tendons significantly reduces peak torsion, and has almost no impact on the bending and shearing capacity. Comparison with the finite element analysis shows that the numerical results calculated by the formulas agree well with the finite element analysis, therefore the formulas can be a simple approach for practical design.