Abstract
The paper presents the nonlinear section analysis for composite steel-concrete beams with different degrees of shear connection. The analysis is fiber based, i.e., integration over the cross section is performed numerically, and any uniaxial nonlinear material model can be assigned to the steel and concrete parts of the cross section or to the reinforcement bars. The analysis assumed full interaction between steel and concrete and therefore, is suitable for analysis of composite steel-concrete beam cross sections with nonductile shear connectors. Its accuracy is verified on few experimental results. The presented section analysis is used in the parameter study in order to evaluate different methods proposed by design codes for determining the bending moment resistance of composite cross sections with nonductile shear connectors and different degrees of shear connection. The following effects are considered: variation of concrete and steel material models, presence of slab reinforcement, and creep of concrete. Special attention is paid on two different constructional methods: propped and unpropped. The weaknesses of the simplified design method in determining bending moment resistance are identified and recommendations for practical design analysis are formulated.
Highlights
Composite steel-concrete structures are in increasing use over the last several decades [1,2,3]
In order to evaluate the analysis methods described in the previous section, the following numerical model for nonlinear section analysis is defined. e analysis is based on the fiber section model and adopts the assumption of the linear strain distribution over the composite section height. e considered cross section from Figure 1(a) consists of concrete slab and steel section. e section is divided into a number of layers since the performed analysis considers only bending about strong axis
In order to verify the section analysis method proposed above, seven experimentally investigated tests are numerically analysed. e first group of tests includes specimens by Zhao and Yuan [11] of the flexural behaviour of steel-concrete composite beams. e beams consisted of the welded steel I section and concrete slab. e section sizes of steel beams satisfied the Eurocode 4 requirements for compact sections
Summary
Composite steel-concrete structures are in increasing use over the last several decades [1,2,3]. Neutral axes in the steel beam and concrete slab differ [16] In these cases, according to design codes, bending resistance of composite section with ductile connectors can be determined using the simple equilibrium method and the rigid plastic analysis [5, 6, 16]. The analysis can take into account the real load-slip behaviour of connectors Since this relation is not always available and since the calculation of slip at the steel-concrete interface involves use of advanced numerical models, the design codes (Eurocode 4 [22], for example) suggest to completely ignore slip at the interface when nonductile shear connectors are used. Ma,Ed is the design bending moment acting on the steel section alone
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