| Corrugated steel web-steel floor-concrete roof composite box girder is an improved structure based on traditional corrugated steel belly composite box girder,which replaces concrete floor with steel floor.The structure is light in weight and convenient in construction and has been applied in practical engineering.Compared with the study on the mechanical properties of the traditional corrugated steel web composite box girder,there are few studies on the mechanical aspects of the corrugated steel web-steel floor-concrete roof composite box girder.There is a lack of theoretical data support in the promotion and application,so it is necessary and meaningful to study the mechanical properties of this new structure.The main research contents of this paper are:? The domestic and foreign literatures of corrugated steel web composite box girder were collected and the development history of corrugated steel web at home and abroad was summarized.The structural requirements,force characteristics,box girder shear lag definition and shear force of the new structure were expounded.Research methods and research status of stagnation;? The energy variation method in analytical method is used to solve the shear lag.The cubic parabola is selected as the warping displacement function to solve the shear lag coefficient and stress of the simply supported and continuous basic structures under concentrated load,uniform load and several load combinations.And the calculation formula of vertical deflection,the stress value and deflection value of the key section are obtained by calculation.The results show that the normal stress is unevenly distributed along the transverse bridge direction,and the deflection value increases proportionally with the increase of the load.? The 8 meters long model test beam was fabricated,and the simple support was continuously tested indoors for static load to obtain the stress value and deflection value of the critical section.The test results show that there are shear lag phenomenon in the simple corrugated steel web and the continuous box girder.With the increase of the load,the corresponding position deflection value increases.? The ANSYS refined finite element model was established according to the size of the model test beam.Firstly,the stress distribution of key sections under symmetric and continuous boundary conditions is studied.Secondly,the distribution law of shear lag is further studied.Finally,the variation of key section deflection with load is analyzed.The results show that the shear lag effect under concentrated load is obviously equal to the shear lag effect under uniform load and the ANSYS value,energy variation method and experimental value are basically consistent.? The distribution law of shear lag coefficient is studied.It is found that the section of the simply supported beam is the most obvious under the concentrated force.The section near the bearing is the most obvious under the uniform load.The two-span continuous beam is concentrated in the middle of the beam.When the cloth load is applied,the most obvious section of the shear lag effect appears in the section near the inner fulcrum.? The effects of different roof thickness,support length,diaphragm spacing,prestress and width to span ratio on shear lag effect of improved corrugated steel web composite box girder are discussed.It is found that wide span ratio is the main influence of shear lag effect.factor. |
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