Performance Analysis And Simplified Calculation Of Bonded Composite Beams With Embossed Steel Plates

Composite beams,such as steel-concrete composite beams,etc.have been widely applied in construction and bridges engineering fields due to their good mechanical properties.At present,the sub-beams of composite beam are connected mainly with the traditional shear connectors.However,due to the limitation of the connection form,there usually exist stress concentration in vicinity of the shear connectors,which can lead to stress failure of the composite beam.At the same time,because of the limited rigidity of the shear connectors,there exists an inevitable relative displacement at the interface of the two sub-beams.Therefore,it is of great theoretical significance and application prospect to study bonded-type composite beams with partial shear interaction,in which bonding technology is employed instead of traditional shear connector.There is a unique and novel construction form in bonded-type composite beam with vertical embossed steel plate studied in this dissertation,which can not only effectively eliminate the stress concentration of traditional shear connectors,but also enhance the mutual bonding between the sub-beams of the composite beam,thereby to make better use of material properties.Taking the deflection and slip displacement of the composite beam as the basic unknowns,the boundary value problem of the bonded-type composite beam with partial shear interaction is established in this dissertation,and the bending behavior of simply-supported two-span continuous composite beams is investigated.On this basis,based on the standard of equivalent deformation,the bonded-type composite beam with vertical embossed steel plate is equivalent to a uniform beam,and the bending rigidity of the equivalent uniform beam is given.The applicability of the equivalent uniform beam model is verified,and the influences material and geometric parameters of composite beam on the fundamental frequency of bonded-type composite beams with vertical embossed steel plates are analyzed.A simple and reliable approximate calculation method is provided for static and dynamic analysis of this type of composite beams.The main contents of the dissertation are as follows:Based on the structural characteristics of the composite beam with vertical embossed steel plates,and under the assumptions that the adhesive layer only deforming in the axial direction and the sub-beams satisfying the bending deformation of Euler-Bernoulli beam,a boundary value problem for bending of the bonded-type composite beam with partial shear interaction was established in the Second chapter,in which the basic unknowns are the deflection and interfacial slip displacement.The analytical expressions of the deflection and slip displacement of the simply-supported two-span continuous composite beam under uniform load are obtained by Laplace transform and its inverse transform.The parameter study is conducted,and the influences of different parameters on the deformation and internal forces of the continuous composite beam with partial shear interaction were obtained.The parameter configuration to reduce effectively the deformation of the continuous composite beam and the negative bending moment at the inner support was investigated mainly,and the method for reducing the negative bending moment at the inner support of the continuous beam is obtained.Based on the research in the previous chapter,the third chapter further studies the bending deformation and the axial strain of the upper sub-beam at the inner support of the simply-supported two-span continuous composite beam subjected to transversal load and longitudinal pressure at both ends of the composite.Analytical expressions for the deflection and slip displacement of this type of composite beam are obtained.The influences of longitudinal pressure at both ends of the composite beam on the deflection of the composite beam and the axial strain of the upper beam at the inner support are investigated,and a reasonable longitudinal pressure imposing method is obtained for the design reference of prestressed composite beams in the engineering.In the fourth chapter,for simplified analysis and design,the bonded-type composite beam with vertical embossed steel plates is equivalent to a uniform beam by the method of equivalent static stiffness,and a general method for determining the flexural rigidity of the equivalent uniform beam is given by least square method.On basis of verifying the reliability and applicability of the equivalent uniform beam model in static analysis,the applicable range of the equivalent uniform beam model for calculating the natural frequency of simply-supported composite beams is examined.Finally,the influence of parameter configuration of the composite beam on the fundamental frequency of the simply-supported composite beam with vertical embossed steel plates is analyzed,and the related conclusions are obtained.