Static And Dynamic Analysis Of Floating Platform On Bridge Construction

The bridge construction in deep water is generally using large diameter boredpiles as bridge pier foundation, and it’s easily influenced by deep water, floods andnavigation, etc. Therefore it’s necessary to set up temporary construction platform toexclude construction interference and solve the problem of accurate positioning, etc.For the reason of that it’s unable to meet the construction requirements of usingstationary platform or floating platform of vessel to complete the bridge construction,which is in the condition of that large lifting equipments are difficult to enter, or thedeep reservoir with basicly no velocity, etc, the floating platform with small pontoonis studied.Firstly, the research status at home and abroad of the construction platform inpile foundation construction in deep water is reviewed. By comparing the advantagesand disadvantages of stationary platform and floating platform, the necessity ofintensive study of floating platform is pointed out.Then, based on the finite element theory, the three-dimensional beam slabanalysis model of the overall floating platform is established. And through the zerodraft assumption and the concept of water spring, the depth of the draft of floatingplatform was compared by using the theoretical results and the uniform andnon-uniform stiffness of water spring under the condition of gravity and partial load.The result shows that it’s more accurate by uing the non-uniformstiffness of waterspring.Thirdly, the displacement and stress distribution of floating platform iscalculated in various operating conditions, by using rigid joint and hinge joint andhalf-rigid joint between pontoons. The result shows that the difference ofdisplacement is small and the difference of stress is large. It’s mainly due to thebigger longitudinal stiffness of floating platform caused by the longitudinal beam ofthe upper working platform. The indicators of the floating platform meet therequirements of the related standard, and the performance of the overall floatingplatform is good.Finally, the dynamic response of the floating platform is analyzed under themoving and impact loads. Due to the large stiffness of the overall floating platformand the speed of the moving gantry crane, the dynamic response of the floatingplatform under the moving loads is not obvious by considering and not consideringthe additional water quality and damping; and the dynamic response of the floating platform under the impact loads is quite different by considering and not consideringthe additional water quality and damping. When not considering, the dynamicresponse of the floating platform appears obvious cyclical increasing, and the peakvalue of the dynamic response is gradually decayed; when considering, the dynamicresponse of the floating platform also has the weak cyclical increasing.