Optimization analysis of steel suspension box cofferdam

In order to optimize the steel suspension box, the element calculation model is set up to analyze its mechanical characteristics during construction at first. The results show that the critical conditions of the whole structure maximum stress occurs during casting the first layer cap concrete at high tide level and the overall stress level is low in every construction condition. Then sensitivity degrees of the whole structure maximum stress to three main components - base plates, main beams in base plates and steel tube brace are researched respectively using sensitivity analysis method. The researches indicate that the whole structure maximum stress is increasing while the base plates thickness becomes thinner, decreasing while the moment inertia of main beams in base plates is added, increasing while the steel tube braces diameter becomes bigger. The researches also indicate the thickness of base plates is the most sensitive to the whole structure maximum stress, comparing to the moment inertia of main beams in base plates and the diameter of steel tube braces. At last, decreasing the moment inertia of main beams in base plates can be used to optimize the steel suspension box considering the overall balance of the structure, deformation and change of stress.