| Prefabricated structure can effectively reduce the generation of construction waste,shorten the construction period and reduce labor costs.Steel concrete composite beams are widely used in engineering due to their light weight and large span.The prefabricated composite beam has the common advantages of both,and the prefabrication of the composite beam is better than that of the concrete beam.At present,there are many researches on precast concrete box girder,but few researches on the connection between precast concrete box girder and steel box girder or steel box composite girder.The connection between precast steel reinforced concrete column and beam is mostly focused on its connection with concrete beam or steel reinforced concrete beam,while the connection between precast steel reinforced concrete column and composite beam is relatively less studied.Therefore,it is necessary to further study the connection of precast composite beam and the joint of composite beam and steel reinforced concrete column,and the mechanical analysis and numerical experiment research of joint were carried outIn this paper,several new types of prefabricated composite beams connected by integral precast slabs and steel beams and the joints of integral precast composite beams were proposed based on the existing connection of prefabricated composite beam;Based on the analysis of the existing joints between concrete box girder and steel beam or composite beam,the prefabricated joint between concrete box girder and steel box composite beam was proposed;Several connection modes of precast steel reinforced concrete column and composite beam were designed by using flange plate,bracket,embedded parts and bolts.According to the characteristics of the joint,the mechanical analysis was carried out,and the bearing capacity calculation formula of the joint and the connector was given.The differential equation of interface slip of steel-concrete composite beam considering creep effect was established,and the calculation formulas of interface slip under different working conditions were derived.With the increase of concrete age,the amount of interface slip decreases gradually,and the law is the same as that of concrete creep,creep has a great influence on it in the first 100 days of loading.Interface slip is basically linear relationship with load and concrete strength.The interface slip is inversely proportional to the connection stiffness,connection stiffness is increased by two times,and the interface slip is reduced by about 65%.ABAQUS was applied to establish the analysis model of composite beam with steel plate and concrete plate in negative moment area and the joint of steel box composite beam with concrete box beam.The parametric analysis was carried out and the following conclusions are drawn:the analysis results of composite beam with steel plate and concrete plate in flange plate show that the influence of stud spacing on it can be ignored;The bearing capacity increases with the increase of the thickness of the steel plate or the height of the concrete flange plate;However,the ductility decreases with the increase of flange height;When the thickness of steel plate exceeds 8 mm,the increase of bearing capacity is no longer proportional to the increase of steel plate thickness.From the deformation curve of the joint section of concrete box girder and steel box composite girder,it can be concluded that the stiffness changes smoothly;The tensile stress of the web of the concrete beam with embedded bolts is large,so the prestressed tendons can be set locally or the fiber concrete can be used in the design and construction;With the increase of the thickness of the bearing plate,the maximum stress of the bearing plate and the steel box girder decreases.When the bearing plate is 60 mm,compared with 50 mm,the maximum stress of the bearing plate and steel box girder decreases by 23.6%and 15%respectively;The influence of bearing plate thickness on concrete beam can be ignored. |
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