| Trough beam is widely used in rail transit system due to its advantages of low building height,high cross section space utilization,obvious noise reduction effect,safe and comfortable driving.Corrugated steel web has the advantages of light weight,simple and beautiful structure.The corrugated steel web is used to replace the concrete web of trough beam to form the composite trough beam with corrugated steel web.Combined with the advantages of corrugated steel web and trough beam,the composite trough beam with corrugated steel web has a good development prospect.In order to optimize the structure of composite trough beam with corrugated steel web and improve the bending capacity,lateral stiffness and working performance of the bottom concrete plate,based on the requirements of efficient construction and high durability of the structure,it is proposed to wrap a thin steel plate outside the concrete bottom plate of composite trough beam with corrugated steel web to form a new structure named composite trough beam with corrugated steel web wrapped with steel plate,which referred to as composite trough beam wrapped with steel plate.This study shows that the proposal of composite trough beam wrapped with steel plate improves the working performance of composite trough beam with corrugated steel web and has many structural advantages.In this paper,theoretical derivation,experimental test and ABAQUS nonlinear finite element simulation were combined to analyze the structural advantages of composite trough beam wrapped with steel plate.This paper studied the bending capacity theory,failure mode and strain distribution of cross section under bending load,shear displacement calculation method,bond slip mechanism and construction method of composite trough beam wrapped with steel plate,summed up the design points of composite trough beam wrapped with steel plate,and verified its feasibility in the field of bridge engineering through the example analysis.The main research contents and conclusions are as follows:(1)In this paper,the equivalent calculation cross section of composite trough beam wrapped with steel plate was proposed,and the calculation method of the bending capacity of composite trough beam wrapped with steel plate under different section types were obtained;The formulas for solving the geometric characteristics of the cross section of composite trough beam wrapped with steel plate were derived,and the method for solving the geometric characteristics of cross section of composite trough beam with complex reinforced section was obtained;Based on the basic assumptions,the height of relative limit compression area of composite trough beam wrapped with steel plate was deduced,the judgment of the limit failure of composite trough beam wrapped with steel plate was analyzed,and some suggestions on the setting of beam materials and the structural reinforcement were put forward.(2)In this paper,two pieces of scaled composite trough beam wrapped with steel plate were designed and fabricated.The processing technology,test point arrangement and loading scheme of the experimental beam were formulated.The failure mode,load-displacement curve and cross section strain distribution of the experimental beam were obtained.(3)The full beam model,half beam model and quarter beam model of composite trough beam wrapped with steel plate were established by ABAQUS finite element software.The modeling differences between different models were compared.The steps of nonlinear finite element modeling process were summarized,and the key points in nonlinear finite element modeling process were summarized;Through ABAQUS nonlinear finite element simulation,the failure mode,bending capacity and load-displacement curves of the scaled experimental beams were compared and analyzed,the correctness of the method for calculating the bending capacity of the composite trough beam wrapped with steel plate was verified.(4)This paper analyzed the load-displacement curve,lateral displacement,crack width and beam damage status of composite trough beam before and after adding the steel plate,verified the structural advantages of composite trough beam after adding the steel plate,and proved the rationality of the new structure of proposed in this paper.The effects of different height span ratio,thickness of steel plate and reinforcement diameter of upper flange plate on bending capacity,load-displacement curve,compression damage status of upper flange plate and tensile damage status of bottom plate of composite trough beam wrapped with steel plate were studied,which can provide reference value for parameter selection in design of composite trough beam wrapped with steel plate.(5)The analytical method and the energy method were used to solve the shear displacement of composite trough beam wrapped with steel plate under different loading conditions,the formulas for solving the shear displacement were obtained,and the differences between the two methods were compared;ABAQUS finite element software was used to verify the correctness of the theoretical formulas,and the effects of different beam parameters on shear displacement and total displacement were obtained.(6)A micro section of composite trough beam wrapped with steel plate was took as an example,the formulas for calculating the bond slip and the additional displacement of bond slip of composite trough beam wrapped with steel plate under different loading conditions were derived;The correctness of the theoretical formulas were verified by ABAQUS finite element software.The parameters such as stud diameter,stud spacing and beam parameter size were selected as the analysis indexes,and the effects of different parameters on the additional displacement of bond slip were studied;The proportions of bending displacement,shear displacement and bond slip additional displacement of the beam under different loading conditions were studied,which provided reference value for parameter selection in the design of composite trough beam wrapped with steel plate.(7)Based on the structural characteristics of composite trough beam wrapped with steel plate,two rapid construction schemes were proposed,and some suggestions on the selection of materials of steel plate were put forward.(8)In this paper,a simply supported composite trough beam wrapped with steel plate was designed,and the checking results of various indexes all meet the requirements of relevant specifications.The research contents can provide reference value for the design and application of composite trough beam wrapped with steel plate in practical engineering. |
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