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Design model for headed studs as shear connectors under additional tensile loading Headed studs are primarily subjected to shear when used as shear connectors in usual steel‐concrete composite structures. Consequently, initial design rules for shear connectors in composite structures did not address tensile forces directly. In case of horizontally lying headed studs embedded in a thin concrete slab such as in composite bridges, the headed studs may be subjected to tensile forces. For horizontally lying studs, current design rules consider a possible failure caused by a tensile load due to pull‐out by specifying geometric boundary conditions. As a consequence, relatively long shear connectors are required, which lead to uneconomical or impractical embedment lengths of the shear connectors. As meanwhile European code rules for fasteners under shear and tension (EN 1992‐4) have been developed, the upcoming Eurocode 4 refers to them for the design of shear connectors under combined tension and shear in composite structures. The fastening technology allows a direct design for tensile loading for different failure mechanisms, considering the influence of the reinforcement and concrete strength. Following this idea, this paper presents a design model for shear connectors in steel‐concrete composite structures under additional tensile loading based on experimental and numerical investigations considering recent developments in fastening technology. [ABSTRACT FROM AUTHOR]

Abstract: Limitations to the use of partial shear connection in composite beams with single flange steel beams and composite dowels – Part 1: Theoretical background, methodology and development of FE‐models. The plastic bending resistance design of composite beams with partial shear connection in EC4 is subject to several limitations of use. For instance, the shear connectors, usually shear studs, have to provide sufficient ductility (at least 6 mm deformation capacity) and the geometry of the steel beam is restricted to sections with either equal flanges or only slightly differing areas of top and bottom flange. Furthermore, EC 4 defines a minimum degree of partial shear connection. For composite members with single flange steel section and composite dowels, limitations to the use partial shear connection have not yet been researched. Because of remarkable differences regarding steel section geometry and deformation behaviour of the connectors a simple transfer of EC 4 rules is not possible and likely non‐conservative. In the first of two companion papers on that topic, the theoretical background and the methodology to investigate the limitations of use for partial shear connection are provided. Besides plastic design of several beams sections with partial shear connection, the paper presents the development of nonlinear, 3D FE‐models of composite beams with single flange steel beam and composite dowels, which are validated against experimental beam tests from the literature. [ABSTRACT FROM AUTHOR]

Abstract: Large‐size HV‐bolt sets in ring‐flange connections are crucial structural members of wind turbine support structures, which are subjected to strong static as well as cyclic loads with considerable numbers of load cycles. Additionally to direct experimental investigations on the structural components themselves, analytical and numerical assessment methods of the bolts performance inside ring‐flanges are valuable engineering tools to gain knowledge about the structural behaviour and to support the development of appropriate design solutions. In this paper, probabilistic fatigue assessment, using Monte Carlo Simulation technique, is utilized to compute the failure probability and to investigate the influence of the scattering parameters on the fatigue performance of HV‐bolt sets in ring‐flange connections. Subsequently, an analytical fatigue calculation approach for large‐size bolts, based on the local strain‐life concept, is introduced. Results from two different methods for determination of required base material properties are compared. The calculations are validated on fatigue tests on HV‐bolt sets and results are discussed with regard to the evaluation of local loading conditions, damage assessment parameters and sensitivity to base material input. [ABSTRACT FROM AUTHOR]

Abstract: Investigations on the load bearing behavior of composite dowels positioned close to the free concrete surface. Composite dowels are an economic alternative to headed studs with various advantages. Modern concrete slabs are dimensioned increasingly thinner and often include several additional functions, for example air conditioning or thermal activation of concrete surfaces. For those applications composite dowels can be positioned horizontally in the concrete slab. Existing investigations on composite dowels describe different failure modes of composite structures such as splitting of the concrete, local compression of the concrete, pry‐out of a concrete cone or plasticizing of the steel teeth. At University of Kaiserslautern composite dowels with positions close to the free surface of the concrete slab were investigated experimentally by push‐out‐tests and on the basis of numerical simulations. In addition, the positive influence of a spiral reinforcement between the steel teeth was analyzed. Further primary and secondary failure mechanisms were observed for this specific position of the composite dowels. These investigations and a design approach will be presented within the paper. [ABSTRACT FROM AUTHOR]

Abstract: Limitations on the use of partial shear connection in composite beams with single flange steel beams and composite dowels – Part 2: Analysis of the load bearing and deformation behaviour and modes for the minimum degree of partial shear connection. For composite beams with single flange steel beams and composite dowel connectors, the limitations to the use of partial shear connection have not yet been clarified. In this paper (continuation of [1]) the bearing and deformation behavior is analyzed using experimentally verified FE models. For this purpose, a comprehensive parametric study is performed, in which, in addition to the degree of shear connection and different cross‐sectional types, different parameters of the composite beam are varied which do not enter into the analytical calculation of the plastic bending moment capacity. These are, on the one hand, properties which depend on the static system, such as the loading situation (single load or uniformly distributed load) and the span, on the other hand, the slip deformation behavior of the connectors is varied by establishing different ductility characteristics for pry‐out and steel failure of composite dowels. Based on the simulation results, equations are derived for the minimum degree of partial shear connection for beams with single flange steel sections and composite dowel connectors including all required limitations of use for plastic design. The own models are compared to regulations given in a technical approval for composite dowels. The models may also be adopted for composite beams with steel T‐sections and horizontally lying shear studs. [ABSTRACT FROM AUTHOR]