Research Of Shear Lag Effect On Double-Level Continuous Box Girder

In the thesis,FEM and plexiglass model test are used for the research of shear lag effect on double-level continuous box girder. Modeling the general solid web continuous box girder and opening-in-web(open web)continuous box girder by ANSYS finite element modeling tool,node stress of governing section and corresponding shear lag values are analyzed.The solution is validated by comparing with variational results and modeling test values.Based on the model,the section shear lag induced by dead load,prestress tendons and car loads under the most unfavorable condition and lateral symmetry are also approached.The influence of shear lag effect in double-level continuous box girder is considered with opening-in-web and the web location.The analysis indicates that double-level-load arouses less shear lag effect than one-level-load.When self-weight and prestressed tendons act on together,the shear lag effect on box girder take on a evidently change. Based on the research of influenced parameters on constant and varying depth solid web box girder before,the shear lag aroused by the parameters including width-span ratio,outstanding flange on base slab and the position of the tendons are further studied.The investigation show that shear lag values diminish along with the decease of width-span ratio and the departure from the symmetrical axis of anchor position,but outstanding flange is contrary to the former. The plexiglass model test is carried out by two selective shape,the stress of each test operating loads was obtained in order to validate the correctness of the finite element modeling.In this paper,a regularity of shear lag effect of main sections in two kinds of box girder is given. As the foresight project of double-level-driveway continuous box girder,this research fully utilizes the space of box girder structure and flexural and torsional properties of high-depth box girder,which have innovative significance and applied foregroundin engineering.