Design And Application Of Highway Steel Concrete Composite Beam Based On Construction Conditions In Qinghai Province

With the development of the theory of steel-concrete structure,the application of steel-concrete composite beam bridge is more and more extensive.Composite beam bridge has irreplaceable advantages in many aspects,but its structure and stress are more complex,so it is necessary to carry out fine mechanical analysis and geometric parameter analysis.Qinghai highway is one of the most important traffic fortresses in China,which can not be ignored in bridge construction.However,the environment of Qinghai Province is characterized by high altitude and high altitude,which will have a significant impact on bridges,especially composite girder bridges.Based on the investigation and research of dozens of highway bridges in Qinghai Province,a series of composite beam design techniques are studied in this paper.As follows:(1)This paper investigates and analyzes the service environment conditions of highway bridges in Qinghai Province,as well as the parameters of existing highway bridges,and summarizes the common problems of highway bridges in Qinghai Province.It is considered that under the environment of high altitude and cold,the composite beam bridge still needs further research in general drawing design,structural structure and application.(2)The section form and structure of composite beam are studied.The results show that the prestressed concrete deck slab of 12.5 m is suitable for the prestressed concrete slab of 12.5 m in Qinghai area;if the cross-section of I-beam is 2.5 m,the composite steel slab with the maximum span of 2.5 m can be used If three pieces are used,it is not necessary to set Transverse Prestress.(3)In this paper,the mechanical properties of composite beams under negative bending moment,shear lag,live load and temperature effect in cold environment are analyzed by using the method of bar system and solid fine finite element.The results show that the stress of composite beam concrete is complex.In order to simplify the design,the longitudinal and Transverse Prestress are not set in the general drawing.According to the reinforced concrete member design,the crack width in the negative bending moment area is controlled at about 0.1 mm.(4)The mechanical properties of wet joint structure of bridge deck with different parameters were tested.The results show that the same bending and tensile bearing capacity can be achieved by directly welding U-shaped steel bars,and the bearing capacity of U-shaped steel bars has no significant change between 350 mm and 550 mm.