Study On Ultimate Capacity Load Of Plate Girders With Perforated Web Under Axial Compression And Bending Moment

While plate girders are commonly used in ships,aircraft applications for their high efficiency and easy-to-study,the ultimate capacity load concern to security and reliability of ship structures.The presence of the openings(perforations)will cause section area decrease,structural discontinuity,stress redistribution and declining of ultimate bearing capacity of the plate girders.In spite of numerous papers in the literatures on plate girders subjected to failure mode of web crippling,the other failure modes such as plate buckling has not been exhaustively examined.The plate girders in ship and offshore structures are usually subject to axial compression and bending moment loads,which is the typical action pattern arising from cargo weight and water pressure together with hull girder motions in ships and ship-shaped offshore structures.Under such combined loads,the failure behavior of the plate girders is hard to predict and the influence of related parameters become complex,the plate girders with perforated web under axial compression and bending moment are rarely studied in the world.In this thesis,the experiment and finite element method are employed to analyze the ultimate capacity load of the plate girders with perforated web under axial compression and bending moment.First,the experiment of the ultimate capacity load of the plate girders with perforated web under axial compression and bending moment was conducted,the phenomenon and detail datas of the specimen were analyzed,the opening strengthening structures were strong enough to ensure the unstability or failure do not appear in the opening area.The failure modes and load-deflection curves of the specimen with opening on midspan and end of the web were compared,it was found that the specimen with opening on midspan has more influence on ultimate capacity load.The finite element mode way was used to predict the ultimate capacity of the specimen and predictions can agree with experimental results well.The finite element model that considering material nonlinearity and geometric nonlinearity was created.the influence of the cell size and partitions was investigated,and initial geometric deflection caused by residual stress was considered.The influence of the opening position and opening size were analyzed based on the model results.The concepts of “failure in opening area” and “failure not in opening area” were proposed based on the failure mode of the specimen.The basic characteristics and law of the influence between the failure mode and the ultimate capacity load were revealed.Finally,optimized proposals of opening parameters were presented.In the last part,five kinds of useful opening strengthening ways were discussed and the influence of the openingstrengthening structures were analyzed.The results showed that ringed stiffenerwas the most efficient of all single strengthening structures.The specification regulated sizes of the strengthening structures were serious surplus when the opening size was small.It was suggested to optimize the sizes of the strengthening structures when easy manipulation.