Behavior Of Shear Connectors Research Articles

Experimental analysis of shear connection between steel and lightweight concrete

This work describes the experimental tests carried out at the University of Minho to evaluate the behaviour of shear connection between steel and lightweight concrete. Two types of shear connectors are studied in the experimental campaign. These are headed studs with 19 mm, 22 mm and 25 mm of shank diameter and Perfobond rib with circular openings. The standard push-out test, as defined in EN 1994-1-1, is chosen for this analysis. The connection behavior is analysed in terms of its load-slip relation and the failure modes are identified. Also, the load capacity, maximum slip, elastic slip and plastic slip are quantified. Some of the push-out tests performed try to isolate the components of the steel to concrete connection in order to evaluate each one’s contribution. All the results that allow the characterisation of the connection between steel and lightweight concrete are compared with the results obtained by other authors with similar specimens made of normal density concrete.

Numerical Studies on Structural Behaviour of Shear Connectors in Push-Out Tests

A generalised three-dimensional finite element model is proposed for the study of structural behaviour of shear connectors in push-out tests of different specimen geometries, as well as different loading and boundary conditions. Concrete slabs, steel beams and shear connectors are modelled with eight-noded solid elements; and profiled steel deckings are modelled with eight-noded double curvature shell elements. It is assumed that steel deckings are bonded perfectly to concrete slabs, so that there is no relative slippage between steel deckings and concrete slabs. The accuracy of the model is verified through the calibration against a series of push-out tests. Premature failure in unbraced specimens due to flexural bending and global cracking in concrete sections was studied, and an analytical model is proposed for a better understanding of this failure mode.

Push-out tests and a new approach for the design of secondary composite beam shear connections

Most of the design approaches currently used around the world take into account the weakening effect of trapezoidal types of steel decking in the vicinity of a shear connection by applying a reduction factor to the nominal strength that the same connection would have in a solid concrete slab. Numerous push-out test results on shear connections incorporating this type of decking are presented. These demonstrate that not every shear connection incorporating profiled steel decking which is within the limits of the associated standards, can be classified as sufficiently ductile. A new and more reliable design approach is proposed which also allows for the inclusion of special reinforcing devices to overcome these brittle behaviours. The key element of this design approach is to classify the anticipated connection behaviour, with respect to its deformation capacity, into either ductile or brittle, hence ensuring satisfactory shear connection behaviour where these types of trapezoidal steel decking are used.

Advanced finite element modelling of perforated composite beams with flexible shear connectors

An extensive research and development programme has been undertaken by the authors to develop advanced analysis and design tools for practical design of long span composite beams in buildings. Both two- and three-dimensional finite element models employing solid and shell elements with material, geometrical and interfacial non-linearity were established to examine the full range structural behaviour of composite beams. In this paper, two-dimensional finite element models employing plane stress elements are established to examine the structural behaviour of perforated composite beams, and shear connectors with non-linear deformation characteristics are incorporated into the models through the use of both vertical and horizontal springs. It is demonstrated that after careful calibration against test data, the finite element models are able to predict the load carrying capacities of composite beams with large rectangular web openings against ‘Vierendeel’ mechanism satisfactorily. Moreover, a number of important structural quantities such as local axial and shear forces together with local bending moments acting onto the composite and the steel tee sections at failure are obtained after data analyses. Together with the load carrying capacities, these quantities compare favourably with the values obtained from a design method proposed previously by the authors, and hence, this provides quantitative justification to the proposed design method. Furthermore, the finite element models provide detailed information on the structural behaviour of shear connectors along the beam length, such as the longitudinal shear forces, the pull-out forces as well as the slippage of the shear connectors. Based on the findings of the finite element modelling, a number of recommendations on the design and construction of perforated composite beams are suggested.

A New Design Proposal for Secondary Composite Beam Shear Connections Incorporating Trapezoidal Steel Decking

An extensive experimental program was undertaken to investigate the behaviour of secondary composite beam shear connections incorporating trapezoidal steel decking. Based on the test results, a new design proposal to determine the shear connection strength was developed, which also incorporates the application of stud reinforcing devices that have been found to significantly improve the behaviour of the shear connection. The new proposal has been coupled with a reliability analysis that has been calibrated to provide a safety index similar to stud applications currently in use. Simple strength reduction factors for the types of trapezoidal steel decking available in Australia are presented, and can be applied to the current shear connection strength as given in AS 2327.1 (Standards Australia, 2003) for a fast and simplified design.

Composite Action of Structural Steel Beams and Precast Concrete Slabs for the Flexural Strength Limit State

This paper addresses the issue of composite behaviour between structural steel beams and precast concrete planks for multi-storey buildings. Whilst it is becoming increasingly more common to use precast concrete planks in the Australian building construction, the benefits of composite behaviour have not yet been fully realised with these systems. The main advantages of this form of construction are that the precast concrete units and the steel frames are both derived from manufacturing technology and share the quality control, accuracy and reliability of factory production and thus lead to savings associated with reduced construction times. This paper provides an initial investigation into the issues that need to be resolved for the shear connection in order to establish composite action. The paper outlines various structural forms including hollow-core or solid precast concrete construction manufactured in Australia and considers the behaviour and design of these systems for ultimate loads. Furthermore, the paper provides some very preliminary test results which were undertaken to consider the behaviour of shear connectors adopting the various accepted practices for construction as outlined in Australia. These should prove useful for structural engineers until a more comprehensive experimental program which considers a whole range of parameters is completed.

Experimental Investigation on the Structural Behavior of Shear Connectors Used in the FRP and Concrete Bridge Deck System

Feasibility study on the use of newly developed FRP and concrete composite bridge deck system is conducted. To lengthen the service life of bridge deck, the steel-free bridge deck system is developed. In this deck system, shear connectors between FRP module and concrete are utilized and structural behavior of shear connectors is investigated experimentally. The result of an investigation reveals that the system is promising.

Performance of shear connection in composite beams with profiled steel sheeting

This paper describes the structural performance of shear connection in composite beams with profiled steel sheeting. An accurate and efficient nonlinear finite element model was developed to study the behaviour of headed stud shear connectors welded through-deck. The profiled steel sheeting had transverse ribs perpendicular to the steel beam. The material nonlinearities of concrete, headed stud, profiled steel sheeting, reinforcement and steel beam were included in the finite element model. The capacity of shear connection, load–slip behaviour of the headed stud, and failure modes were predicted. The results obtained from the finite element analysis were verified against experimental results. An extensive parametric study was conducted to study the effects on the capacity and behaviour of shear connection by changing the profiled steel sheeting geometries, the diameter and height of the headed stud, as well as the strength of concrete. The capacities of shear connection obtained from the finite element analysis were compared with the design strengths calculated using the American Specification, British Standard and European Code for headed stud shear connectors in composite slabs with profiled steel sheeting perpendicular to the steel beam. It is found that the design rules specified in the American and British specifications overestimated the capacity of shear connection, but the design rules specified in the European Code were generally conservative.

Behaviour evaluation of shear connection by means of shear-connection strips

Comparison of behaviour of shear connections by means of shear-connection strips (perfobond and comb-shaped strips) and headed studs under static and repeated loading, possible failure modes of concrete dowels and ways of the quantitative differentiation of some failure modes are described in the paper. The article presents a review of knowledge resulting from the analysis of shear-connection effects based on tests of perfobond and comb-shaped strips carried out in the laboratories of the Faculty of Civil Engineering of the Technical University of Kosice (TU of Kosice) in Slovakia and their comparison with results obtained by other authors.rn

Composite Behavior of Shear Connections in Full-Depth Precast Concrete Bridge Deck Panels on Steel Stringers

This study investigates the composite behavior of full-depth precast concrete bridge deck systems under static loading. Entailed is a detailed evaluation of quarter-scale and full-scale system components, with a focus on the number of pockets per specimen, number of studs per pocket, and the benefits of a grouted haunch for the connection between the precast slab and its supporting system.

The behaviour of through-deck welded shear connectors: an experimental and numerical study

This paper describes a study of the behaviour of shear connection between steel beams and composite slabs, which use through-deck welded shear connectors. An experimental study involving three push-out test specimens was carried out and these test results were discussed. A push-out test specimen was simulated and analysed in both two and three-dimensions. The effect of the inclusion of profiled steel sheeting, the effect of the width of a concrete slab, and the effect of different loading and support conditions have been discussed. The pull-out strength of the concrete has also been studied and compared with the experimental results of tests carried out by the authors and others. A new expression based on wedged cone failure has been developed for the effective width of a concrete slab in a two-dimensional numerical analysis.

The behaviour of shear connections in a composite beam with a full-depth precast slab

For the design of shear connections with a full-depth precast slab, it is necessary to investigate strength, stiffness, slip capacity and fatigue endurance. For these purposes, push-out tests were performed with variations of the stud shank diameter and the compressive strength of the mortar. From the experimental work, it could be observed that the deformations of the studs in a full-depth precast slab were greater than those in a cast-in-place slab. The static strengths of the shear connections obtained agree approximately with those evaluated from the tensile strength of the stud shear connectors owing to the effect of the bedding layer. An empirical equation for the initial shear stiffness of a shear connection is also proposed. On the basis of the results of push-out tests, a full-scale composite beam with 8·0 m span was designed and fatigue tests were carried out to study the behaviour of the stud shear connection and its effects on the flexural behaviour of the beam. The bonding and friction between the concrete slab and the steel beam considerably increased the fatigue endurance of the shear connection. Discussions about design are also presented.

The longitudinal shear behaviour of a new steel sheeting profile for composite floor slabs

Longitudinal shear failure is the most common failure-type in composite slabs. In this paper, the shear-connection behaviour of composite slabs with a particular profiled steel sheeting having a depth of 153 mm is experimentally studied. Twenty-seven push-out test specimens of different shapes, sizes, locations of embossments and different steel sheeting thicknesses are carried out in two test series. The embossments are first rolled onto the profiled sheeting, then every embossment is punched through along one side. It is found that the shear-connection behaviour of composite slabs is significantly affected by the depth of embossments. For the profiled steel sheeting with penetrated embossments, the reduction of Young's modulus caused by the penetrated embossments is an important factor that affects the determination of the depth and width of the embossments. Finally, a new type of profiled steel sheeting, which can offer longitudinal shear strength in composite slabs up to 0.6 N/mm 2, is proposed for further research.

Inelastic behaviour of shear connection by a method based on FEM

The aim of the present paper is to propose a new numerical methodology to simulate the push out test in order to investigate the behaviour of shear connectors in composite structures. This methodology is based on the Finite Element Method (FEM). The load-slip curves for shear connectors are mainly based on empirical relationships. The proposed method has the advantage of taking into account the exact geometry of the push out test arrangement, the material description and the load conditions. Then, linear and nonlinear behaviour of the shear connectors can be considered with accuracy. A series of push out tests has been performed at the Laboratory of Steel Structures of the Democritus University of Thrace, and the obtained results are compared with those from the FEM analysis. Thus the method could be a possible substitution for the push out tests.

A finite element for modelling the nonlinear behavior of shear connectors in composite structures

A three dimensional bar element has been developed that can be used to model the nonlinear behavior of the shear connectors in composite concrete-steel structures. An available empirical shear force-shear deformation relationship is utilized to establish the shear stiffness properties of the element. The flexural and torsional stiffness of the bar are ignored while the axial deformations are accounted for similar to normal beam element. The element is implemented in a nonlinear finite element program and its implementation is verified by the analyses of two beams tested by others. The good comparison between the analytical result and experimental data demonstrates the accuracy of the proposed element.

Behaviour of shear connectors under dynamic loads

The details of an experimental investigation of the fatigue strength of stud type shear connectors are described. A new type of test set-up called ‘New Standard Test Method’ has been employed to assess the fatigue strength of an individual shear connector. The results of the fatigue tests are discussed and a simple relationship between the stress range and the number of cycles has been obtained. This relationship is compared to the one obtained by Slutter on the basis of his experiments.