Effect Of Shear Lag For Skew Pre-stressed Concrete Box-section Girder Bridge Under Moving Vehicular Loads

When the transportation is constructed, the choice of line can be more optimized by skew box girder. It can be better able to adapt to changes in line. The skew box girder is widely used in the design now. When we do some study of skew box girder, static force was used to load to bridge before. When the vehicle moving load applied to skew box girder, the study of shear lag effect is not done enough. The skew box-section girder bridge finite element model under dynamic load is established in this thesis. Some study and discussion about the shear lag effect of skew box girder caused by vehicle moving load are done.The 3-D physical finite element mode of simply skew box-section girder bridge and three-span skew box-section girder bridge is established by ANSYS. First, vehicle and bridge model is introduced. Vehicle is simulated by a quarter vehicle mode with six parameters and two degree of freedom. Skew pre-stressed concrete box-section girder bridge is simulated by SOLID65 and LINK8 element. Through compare with already published literature, the correctness of dynamic analysis model is proved. Then, the most unfavorable section of skew box-section girder bridge is analyzed. The change trend of its shear lag effect under dynamic load with the change of parameters is studied. These parameters are mainly include: driving eccentric and slope and traffic conditions and width-span radius and flange width and diaphragm number and pre-stress value and weight of the vehicle and length-span radius. The following results is obtained:The mid-span section is the most unfavorable one in the simple skew pre-stressed concrete box-girder bridge. With the change of parameters, driving speed, wide-span ratio and traffic condition have more effect to its shear lag effect through calculation. Every mid-span section is the most adverse section in the three-span continuous skew pre-stressed concrete box-girder bridge. Driving speed, wide-span ratio, traffic condition and diaphragm number have more effect to its shear lag effect through contrast. At last, some suggestions are given to reduce shear lag effect at the end of this thesis.