Calculation of Cable Force for Long-Span Multi-rib Arch Bridge Construction Based on Zero-Order Optimization Method

Daning River Bridge is a steel truss arch bridge with triple-ribs. Its´ main arch were installed by non-bracket cable-stayed suspension. Calculation of cable force is a key problem while segments were assembled. For structural features of this bridge, an optimization method was presented, which regarded minimum displacement deviation caused by cable force and self-weigh between cable-released arch and naked arch as objective function, chord stresses and tower deformation caused by buckle cable and anchor cable as constraints. According to the zero-order optimization method, a specialized program to compute cable force was developed with ANSYS Parameter Design Language (APDL). There are two procedures: cable force of sectional installation was firstly determined by zero-order method then taking the results as initial values, cable force of step segment was iteratively calculated. Thus, elevations of three arch ribs being assembled in turn were consistent with objective of sectional installation. By means of comparison of the optimized results and measured values, it found that cable force is uniformly, and the influence of cable force is very small for subsequent construction phase.