Research On Structural Strength Criterion Of Pontoon Bridge Combining With Catamarans

Pontoon bridge analyzed in the present paper is a kind of separated floating bridge combined with series of catamarans by hinged joints.The pontoon bridge which has lower cost,shorter construction period,larger carrying capacity and better economy plays an important role on river-crossing traffic in the Yellow River,and it has been promoted abroad in recent years.But it is pity there have been no proper rules for designing and constructing the pontoon bridge until now.The catamaran is short and wide,but the cross structure is single deck.The driving direction of the vehicles is mainly along the width direction of the catamarans,and the traffic load is increasing,so transverse strength is worth considering.In the present paper,a pontoon bridge with kiloton level two-way four-lane traffic is taken into account.Full-scale test and numerical simulations are combined in this paper to conduct the research on the structural strength of the pontoon bridge.To achieve the research goals,main attention and energies have been devoted into the following aspects:(1)Considering its characteristics and actual loading conditions,the methods on structural strength direct calculation are proposed.Three-dimensional whole ship finite element model is generated firstly.Calculation cases are determined considering the structural characteristics and the severest loading situation.The proper dynamic effect is taken into account by dynamic loading coefficient.Spring element is adopted to simulate the change of buoyancy due to the vehicle load.Structural strength of catamaran and connecting structure is evaluated.(2)Transverse bulkhead structure arrangement and amount of reinforcing plate on the cross structure have an effect on the structural strength,so the influence of them on the structural strength is discussed in order to choose the better structure layout.Besides,increasing cross structure span can decrease amount of catamaran,which can effectively reduce costs,so the influence of it on the structural strength is studied for increasing the span reasonably.(3)The dynamic loading coefficient test of the pontoon bridge subjected to moving load is carried out,for obtaining the proper dynamic loading coefficient.The influence of moving speed and weight on the dynamic stress is revealed.Then the maximum dynamic loading coefficient is analyzed.(4)Axle load distribution of heavy vehicle under different longitudinal gradient is investigated by conducting in-situ test and model experiment.The maximum longitudinal gradient of the pontoon bridge is analyzed to ensure the safe pass of vehicles.(5)Dynamic stress test is performed to validate the proposed structural strength direct calculation method and to make clear the stress levels of structure.It is showed that the test result has good agreement with the computational result.