Research On The Effective Flange Width Of Twin-cell Box Girder

At present, the domestic specification gives the curve of the effective distribution width of single-cell box girder and simply refer to the table in order to obtain the effective distribution width value of simply supported beam, continuous beam and cantilever beam, which is single-cell box girder. However, twin-cell box girder is widely used in the engineering, but the effective distribution width of twin-cell box girder without corresponding reference basis, it is indispensable to consider the twin-cell box girder shear lag effect, the effective distribution width of twin-cell box girder and draw the effective distribution width curve of twin-cell box girder. This paper studies under the Natural Science Foundation of China which are Space Mechanics and Finite Segment Method of Thin-Walled Multi-cell Box Girders, Shear Lag Effect of Thin-Walled Multi-cell Box Girders Supported by Cables and Shear Lag Behavior of Prestressing Effect on PC Box Girders. The main research results are as follows:(1)In order to obtain fine finite element analysis model of twin-cell box girder by shell element and beam element, establishing APDL parametric finite element analysis model of simple supported beam with twin-cell box girder,using the two element simultaneously. By the stress and deflection, and comparing to the experimental results, determining modeling method of twin-cell box girder by shell element and beam element.(2) Reference existing twin-cell box girder section design standard and 200 finite element analysis models are established with different box girder of depth-span ratio, web plate spacing, the angle of inclined web, roof and floor thickness and web plate thickness,summarizes the simple supported beam with twin-cell box girder across the mid span of the effective flange width value distribution, and the parameters of the distribution curve is established based on stochastic method. By comparing to effective flange width value of single-cell box girder in existing standard, found that the stiffness reduction of the structure according to existing standard is unsafe. Therefore, it is necessary to establish special value curve of effective flange width aim at the simply supported beam with twin-cell box girder.(3) Reference existing twin-cell box girder section design standard and 480 finite element analysis models are established with different depth-span ratio, side span ratio and section in detail size of twin-cell box girder, summarizes the continuous beam with twin-cell box girder across the mid span of the effective flange width value distribution, and the parameters of the distribution curve is established based on stochastic method. Across the beam section of the span of continuous beam flange distribution width discount impairment will be smaller than the standard single-cell box girder discount impairment; Side span across the beam section of the effective flange distribution width coefficient and single-cell box girder specification is close to the value.(4) Reference existing twin-cell box girder section design standard and 200 finite element analysis models are established with different depth-span ratio and cantilever length and cross section size of the details of twin-cell box girder, summarizes the cantilever beam with twin-cell box girder across the mid span of the effective flange width value distribution,and the parameters of the distribution curve is established based on stochastic method.According to different width span ratio, some structure in the existing specifications of single-cell box girder based on the distribution of effective flange width provisions is modified, not a single single-cell box girder effective width of box girder is adopted to improve single-cell box girder of the cantilever beam stiffness reduction.(5)Statistical analysis data for the effective flange width distribution of the simply supported beam with twin-cell box girder across the mid span, continuous beam with twin-cell box girder across the mid span and the cantilever beam with twin-cell box girder across the mid span. Combination of reliability theory, draw the design proposal curve of effective flange width distribution of the simply supported beam with twin-cell box girder across the mid span, continuous beam with twin-cell box girder across the mid span and the cantilever beam across the mid span. for the selection of the twin-cell box girder design.