| ABSTRACT:On the basis of detailing the present status of research and methods, the thesis associated with the practical projects tightly, and researched the shear lag effect in ultra wide double-triangle side box girder of concrete cable-stayed bridge. The main contents that were presented in the thesis were summarized as follows:1. Based on the method of solving the shear lag effect in box-girder by the Bar Simulation Method, the expression of double-triangle side box girder stiffener’s equivalent area was derived. According to the characteristics of double-triangle side box girder section, the main girder relied on tower roof’s shear lag coefficient was solved by means of classical3-bar simulation method. By means of the establishment of general bar simulation method’s differential equation and its solving thought, the simply-supported double-triangle side box girder’s floor differential equations were deduced under uniform or concentrated load, and the expression of each coefficient was obtained by solve the differential equations. Combined the solved differential equations with the backing project’s section coefficient, the shear lag coefficient of towrer box girder floor could be calculated, and the correctness of the result was verified by local segmental model;2. The horizontal distribution features and diffusion Angle of the inhaul cable horizontal force was obtained by establishing finite element model based on the practical projects. Combined with the diffusion feature of the inhaul cable horizontal force and Saint-Venant principle, the stress characteristics of girder under different load was analysed by the local segmental model. The analysis result of the local segmental model was verified by using the measured normal stress distribution of the similar bridge. The normal stress distribution and shear lag of the major construction state and the completion state was analysed through multiple local segmental models. At length the effective width of top flange and bottom flange in the completion state was obtained according to the concept of effective distribution width.3. The influence of transverse prestress on normal stress distribution law and the shear lag was analysed by establishing the local segmental model. Combined with the complicated influence of the transverse prestress on the longitudinal stress, then the shear lag effect sensitivity to longitudinal clapboard forms, straight web thickness, straight web spacing and inclined web thickness was separately analysed in detail. The most significant factors was transverse prestress, Followed by straight web spacing. |
