Research On Shear-Lag Effect In Bridge At The Cantilever

Thin-walled box girder is often used in modern bridge engineering. However, there is shear-lag effect in thin-walled box girder when thin-walled box girder is bent in the longitudinal direction. If neglect the shear-lag effect, it will cause the insecurity of design work of construction. Recent years, some scholars have done some studies and discusses about shear lag, but there are many problem.This thesis expatiates the conception of the shear-lag effect about thin-walled box girder and its disadvantage to structure, makes a summary of a variety of theories and methods to solve the shear lag problem in engineering group. The applicability and limitation about above theories and methods are particularly comment in this thesis and it gives the research prospect. Due to the supposition of the longitudinal displacement function is not in accord with fact. This thesis supposes that the longitudinal displacement function is distribute according to m-degree parabola, uses energy variation method derives the differential equation and the closed-form solutions of the box girder in transverse load. Then does some examples, compared with the results obtained from ANSYS and from energy variation method, determines the m.Simulation analysis is made in construction phase of continues bridge by means of ANSYS finite element analysis software, find the distribution of the shear lag in cantilever construction. The comparison analysis is made between the ANSYS result and other method result, the results fit together very well. The distribute regulation of the shear-lag effect can be found, and based on it we can offer the important according for cantilever designation and construction.