桁式钢管混凝土系杆拱桥拱轴线及吊杆索力优化

目前，针对桁式拱系杆拱桥拱轴线形和吊杆索力优化研究相对单一，为得到下承桁式钢管混凝土系杆拱桥的最佳成桥状态,对拱轴线形和吊杆索力进行一体优化。通过基于影响矩阵的最小结构体系应变能原理对吊杆索力进行优化,并利用Matlab中无约束优化算法进行求解；采用桁式拱肋主管偏心距最小法对拱轴线进行优化。经过迭代计算,得到一组满足偏心距阈值的无约束优化吊杆索力和拱轴线形。结果表明：优化后的吊杆索力较优化前更加均匀且均有不同程度的减小,短吊杆索力减小近30%,其抗疲劳性能得到大幅提高；成桥状态下主拱受力良好,上、下弦杆的跨中弯矩小且均匀,轴力值有所降低；优化后主梁端部截面弯矩值有所增大,轴力值基本不变,优化效果不明显；主拱上、下弦杆钢管和混凝土截面分配应力均小于材料承载力,均符合规范要求。

Optimization of Arch Axis and Suspender Cable Force of Truss Concrete-filled Steel Tubular Tied Arch Bridge

At present, the research on the optimization of arch axis shape and suspender cable force of truss arch tied arch bridge is relatively simple,in order to obtain the best completion state of the truss type concrete filled steel tube (CFST) tied arch bridge, the arch axis and suspender cable forces are optimized. Based on the influence matrix , the strain energy of the minimum structural system was used to optimize the cable force of suspender, and the unconstrained optimization algorithm was used to solve the cable force of suspender by Matlab. The arch axis is optimized by using the method of minimization of main eccentricity. After the iterative optimization calculation of the suspender cable force and the reasonable arch axis, the unconstrained optimized suspender cable forces satisfying the eccentricity threshold and reasonable arch axis are obtained. It is shown that the optimized suspender cable force is more uniform and decreases in different degrees than before. The shortest suspender cable force decreases by nearly 30%, and its fatigue performance improves greatly. The strain energy of the main arch structure decreases, the bending moment of the upper and lower chords is small and uniform, the axial force value decreases, and the main arch shows good stress state. However, the bending moment of the main beam section increases and the axial force unchange basically after optimization, the optimization effect is not obvious. The distributed stress of steel tube and concrete sections of the upper and lower chords of the main arch does not exceed the bearing capacity and meets the requirements of the criterion.