Analysis of Mechanical Behavior in Construction of Oblique-pulling Truss Bridge

Cantilever installation is a commonly used method of construction in the superstructure construction of oblique-pulling truss bridge.For considering construction safety,the mechanical behavior was analyzed for each phase of superstructure construction of the bridge.Based on building 3-D finite-element model of Kaziwan Bridge,girder's alignment,key section's stress and stability of the different construction phases were calculated,and the comparative analysis between the calculation results and the test's results on vertical displacement,axis deviation,key section's stress was carried out.The results show that(1) the measured values of vertical displacement are smaller than the calculation values due to actual stiffness of structure is larger than theory stiffness;(2) change rules between the theoretical calculation and the measurement value of key section's stress of the bridge agree pretty well in the construction,and structural mechanical behavior is the most disadvantageous from the maximal cantilever length phase to entire bridge closure phase;(3)the outward direction stability is obviously poor than the inward direction stability with cantilever length increasing and local outward loss stability is quite obvious on partial truss members.