The Top Flange Effective Width Of Steel Box-girder Bridge

In the design of steel box-girder bridge, the shear lag effect of box-girder with wide flange and small span is outstanding . In elementary beam bending theory, it is assumed that the stresses are constant through the width of the beam. However, for the wide flange girders, the stresses are not uniform. This variation of stresses is due to the action of in-plane shear strain in the plate, which is termed"shear-lag". Stresses larger than the elementary bending uniform stress thus develop at the web-flange connection. An appropriate reduced"effective width"of the plate-with the uniform stress equal to the maximum longitudinal stress-has been widely used by engineers in conjunction with the elementary beam bending theory . There are not definite code provision of evaluation of effective width about steel box-girder in many countries, especially curved bridge because its evaluation of effective width vary with the radius of the curve. In this paper ,the practical tables calculating the effective width of different structures are provided to perfect formulation concerned in the standard. A combination of finite element method and software ANSYS are adopted to analyse the simple supported-span, the continuous span, the curved simple supported-span and the curved continuous span to provide the practical tables calculating the effective width.As is well known, the effective width depends on several factors, such as the cross-section width, the height of web, the spacing of span and so on. We can conclude that width/span ratio(overhang width/span and central width/span)is the governing factor of the effective width. The effective width is not constant along the span of girder, and different point of interest in the span should be selected according to the different structure. For simply supported-span, mid span is selected as the point of interest. For continuous span, the whole span is divided into several...