No abstract

The elastic collapse of long cylinders under combined external pressure and axial force was investigated using analytical approach. Long cylindrical pipelines laid on the seabed are subjected to external pressure, initial defect will cause the local collapse of the pipelines. Due to the change of subsea environments and construction conditions, circular pipelines are subjected not only to the hydrostatic pressure, but also to forces of other forms, such as axial tension or compression, so on and so forth. This paper studies the local collapse and the morphological characteristics of a circular pipelines subjected to hydrostatic pressure and axial force. Governing equations based on Karman-Donnell`s shell theory are derived and are solved using Ritz method.

We establish the entity model of groove beams in Midas FEA. Then we compare and analysis the shear lag effect of prestressed reinforcement caused in different locations. It can provide some suggestions for prestressed rib of groove beams. The result shows that when the prestressed steel beam is located in the middle of small beam, the effect of shear lag is maximum and the shear lag effects of prestressed in two ends are similar, Prestressed reinforcement can be arrangement refer to the results.

We use the finite element software Midas FEA to set up space entity model, and discuss various factors including the stiffness of bearing, counteracting force of adjacent beam, the influence of the stiffness of bridge pier on reaction at support. In the practical engineering. Coupling of shear lag, stiffness of beam, bending-torsional coupling and partial load can also affect the redistribution of reaction at support. Through the simulation of the finite element software, we check the support of a railway bridge in Guangzhou city. In the end we found that the stiffness of beam can make the middle support have a tendency to increase. If we take all the factors into account, the force of the middle support will be greater than on the both ends of bearing and the force on the both ends of bearing will be approximately equal.