Welded Stud Shear Connectors Research Articles

Statistical modeling and safety analysis for developing design resistance of deconstructable HSFGB shear connectors in composite beam

In recent years, the high-strength friction-grip bolt (HSFGB) shear connectors in steel-concrete composite beams as deconstructable connectors are of great research interest since they are aligned with sustainable construction. However, the design strength equation for this type of connector has not yet been provided by the design codes such as AISC and Eurocode 4. In this paper, with regard to the reliability aspect, the design strength equation of HSFGB shear connectors is investigated which is projected into a partial safety factor according to Eurocode 4. Accordingly, the three-dimension finite element (FE) push-out model of the composite connection is developed and verified via experimental results to predict the load-slip behavior and failure modes in this type of bolted shear connector. Then One-Factor-at-a-Time (OFAT) method as a sensitivity analysis and Plackett-Burman (PB) design method as a screening analysis are utilized to identify the effective factors of the ultimate strength of HSFGB connectors. Finally, based on a complete database of all existing experimental findings, the results obtained from 55 three-dimension finite element models conducted in this paper, and appropriate statistical analysis, a high-precision equation for predicting ultimate strength is provided. Then the value of the partial safety factor is determined through a reliability study in accordance with EN1990, which provides an acceptable level of safety for the proposed design equation based on Eurocodes. Reliability analysis found that a partial factor of 1.52 was justified for the design strength of HSFGB connectors, which differed from the partial factor of 1.25 stated in the EC for welded stud shear connectors.

Reliability analysis of welded stud shear connectors on simply-supported bridge girders

This paper examines the reliability of welded stud shear connectors for steel-concrete composite bridge girders. A finite element model of a simply-supported bridge was created featuring link connector elements representing the shear studs between beam and shell elements, representing a steel girder and concrete deck, respectively. The model is programmed using a program interface to build a model including studs with random strengths. Using this approach, many analyses can be run in succession, with connectors failing between each analysis. This study considers the probabilistic characteristics of the welded studs and truck loading and recognizes the interaction between ultimate limit state and fatigue limit state. The example bridge employed in this study was designed according to the CSA S6-2014 code provisions. Based on the presented reliability analysis, an increase in the CSA S6-2014 24 MPa endurance limit of at least 1.45 times is found to be acceptable.

Full and Partial Interaction Analysis of Single Span Double Skin Composite Beams with Frictional Force

Double skin composite (DSC) construction consists of a layer of a plain concrete, sandwiched between two layers of relatively thin steel plate, connected to the concrete by welded stud shear connectors. This construction acts in a similar way to doubly reinforced concrete elements but the flexibility of connection between the steel plates and concrete gives rise to interface slip and additional overall element deflection. This results in a strong and efficient structure with certain potential advantages over conventional forms of construction. This paper presents a theoretical analysis of the behavior of simply supported single span DSC beams, assuming both full and partial interaction. The partial interaction analysis takes into account the flexibility of connection on both tension and compression faces. The partial interaction analysis is extended to cover the influence of frictional forces between the concrete and external steel plates, at the supports and load points. The theoretical solutions based on partial interaction theory, assuming realistic material and shear connector properties and incorporating the influence of interface frictional forces between the concrete and external steel plates, at the supports and load points, are compared with the results of tests on DSC beams. It is concluded that the proposed method shows good correlation with real behavior and may be reliably used for the analysis of simply supported single span DSC beams.

Experimental Investigation on Shear Connectors in Steel-concrete Composite Deck Slabs

Background/Objectives: The steel-concrete composite construction has become an effective construction practice in the recent years. The cold form profiled sheet acts a platform for during the construction phase and acts as an external reinforcement after the construction. In steel-concrete composite construction, the shear connectors transfer the longitudinal shear force across the steel flange/concrete interface. The ability to transfer longitudinal shear force by shear connectors mainly depends on the strength of concrete against longitudinal cracking and mechanical properties of the shear connectors. This research investigates shear connector's capacity; the experimental investigation is involved using push-out test for two sets with different shear connectors framing to the profile steel sheet. Methods/Statistical Analysis: Set-W consists of three composite slab specimens with welded stud shear connectors, while set-B consists of three composite slab specimens with bolted shear connectors. Trapezoidal profile steel sheet of thickness 1 mm with rectangular embossments is used. Several key parameters of the composite slab are examined and measured, including slippage capacity, load carrying capacity, composite slab ductility and failure mechanism. Findings: the welded shear connectors provided a better performance in resisting slippage and providing a welded set higher load carrying capacity, however, the bolted shear connector specimens set showed more ductile behavior as compared to of specimens.

Behavior and strength of welded stud shear connectors in composite beam

In this paper the behaviour of stud shear connectors in composite structures is analysed. The composite section is formed by steel profiles connected to solid concrete slabs. Some effective numerical models using the finite element method to simulate the push-out test are proposed. The results obtained from the numerical analysis were verified against experimental results. The material nonlinearities were considered in the models. A bilinear model for steel was considered, and a model of plastic damage (Concrete Damaged Plasticity) in concrete was also adopted. The shear connection capacity obtained from the finite element analysis is compared with the connection strength calculated using the American Specification and the European Code for headed stud shear connector in solid slab composite section. Modifications to existing expressions in these codes are proposed. New factors that improve the prediction of the shear connection capacity are considered.

Elatic Bending and Buckling of Steel-Concrete Composite Plate Considering Slip Effect

Steel-concrete composite plates are formed using steel plates connected to a concrete slabs by means of welded stud shear connectors. The flexibility of connection between the steel plates and concrete gives rise to interface slip and additional deflection. An analytical model considering slip effect for composite plate is presented in this paper. Analytical solutions for deformation of composite plate under lateral load and elastic critical buckling load of composite plate under axial compressive load are deserved. The model and the solutions are then validated by means of finite element analysis. According to the parametric study, when impact factor greater than 5, the critical buckling load of simply composite plate is close to the superposition of the critical buckling loads of steel and concrete slabs and the interaction of both slabs can be ignored.

Full-scale tests on composite steel–concrete beams with steel trapezoidal decking

This paper describes the detailed testing of two full-scale steel–concrete composite beams comprised of composite slabs with deep trapezoidal decking connected to universal beams by welded stud shear connectors. The ribs of the decking were orthogonal to the longitudinal axes of the steel beams. This situation exists in secondary beams in flooring systems of steel framed buildings, and beams with deep trapezoidal slabs of this type are economic since they are able to span large distances, with or without propping. Despite the popularity of these decks and many useful research contributions over several decades, there are some concerns related to the strength and ductility of the shear connection because of the large voids in the slab and the need to place the studs off-centre to circumvent welding them through the longitudinal stiffener in the rib. There is also significant disquiet as to the applicability of push test results on much smaller specimens to the design of full-scale beams. The experimental work in this paper therefore intends to provide benchmark data for the calibration of theoretical models and of design recommendations. The beams were 8 m long with low degrees of shear connection. The tests showed that both beams behaved in a very ductile fashion with the ultimate moment capacities being above those predicted from the Eurocode 4 guidelines.

Local Buckling of Steel Plates in Double Skin Composite Panels under Biaxial Compression and Shear

[Abstract]: Steel plates in double skin composite (DSC) panels are restrained by a concrete core and welded stud shear connectors at discrete positions. Local buckling of steel plates in DSC panels may occur in a unilateral mode between stud shear connectors when subjected to combined states of stresses. This paper studies the local and postlocal buckling strength of steel plates in DSC panels under biaxial compression and in-plane shear by using the finite element method. Critical local buckling interaction relationships are presented for steel plates with various boundary conditions that include the shear stiffness effects of stud shear connectors. A geometric and material nonlinear analysis is employed to investigate the postlocal buckling interaction strength of steel plates in biaxial compression and shear. The initial imperfections of steel plates, material yielding, and the nonlinear shear–slip behavior of stud shear connectors are considered in the nonlinear analysis. Design models for critical buckling and ultimate strength interactions are proposed for determining the maximum stud spacing and ultimate strength of steel plates in DSC panels.

Experimental investigation and design of longitudinal shear reinforcement in composite edge beams

The development of a new reinforcing component is reported. Its primary function is to prevent a special type of longitudinal shear failure from occurring in composite edge beams when profiled steel sheeting is laid transverse to the longitudinal axis of the steel beam, and welded-stud shear connectors are fastened through the sheeting either directly or in pre-cut holes. This brittle failure mode, referred to in the literature as a rib shearing failure, comprises horizontal splits that form in the concrete between the tops of the steel ribs in pans where there are shear connectors, while the failure surface locally avoids the studs by passing over their heads. It has been reported in the literature to have occurred on numerous occasions in push-out and beam tests, and is even shown to occur in tests on beams incorporating typical Australian profiled steel sheeting products with narrow, widely spaced steel ribs, and detailed in accordance with British Standard BS 5950, Part 3.1 and Eurocode 4, Part 1.1. It is now mandatory in Australian Standard AS 2327, Part 1 to reinforce against rib shearing failure. Other potentially important applications for the reinforcing component are also described.

Discussion

Discussion of ‘Fatigue of Welded Stud Shear Connectors in Steel-Concrete-Steel Sandwich Beams’ by T.M. Roberts and O. Dogan, J. Construct. Steel Res. 45(3) (1998) 301–320.

Fatigue of welded stud shear connectors in steel–concrete–steel sandwich beams

A series of tests to investigate the fatigue strength of welded stud shear connectors, attached to the tension plates of steel–concrete–steel sandwich beams, is described. Results of the beam tests are compared with the results of a series of push shear tests and also with the S– N curve for welded stud connectors given in Eurocode 3. The fatigue strength of the stud connectors, determined from the beam tests, was significantly higher than the fatigue strengths determined from both the push shear tests and the EC3 S– N curve. It is concluded therefore that the EC3 S– N curve provides a satisfactory basis for fatigue assessment of welded stud connectors in steel–concrete–steel sandwich beams.

Shear Strength of Composite Plate Girders with Web Cutouts

An experimental investigation of the shear strengths of composite plate girders, with centrally placed rectangular web cutouts, is described. A series of tests is conducted on short‐span girders having conventional welded stud shear connectors, connecting the composite concrete slabs to the top flanges of the plate girders. These tests indicated that it is the tensile or pullout capacity of the connectors that is primarily responsible for sustaining the composite action under predominantly shear loading. Subsequently, a further series of tests is conducted on short‐span girders with bolted tension connectors, designed to offer negligible resistance to horizontal shear forces at the interfaces between the concrete slabs and plate girders, which confirmed the previous conclusion. Both series of tests indicate that if adequate connectors are provided between a plate girder and a composite concrete slab, the shear strength of the composite girder is significantly higher than that of the plate girder alone. A simple analytical model for predicting the shear strengths of composite plate girders is also presented, which shows satisfactory correlation with the test results.

Partial interaction analysis of double skin composite beams

Double skin composite beams are formed using steel plates connected to a concrete infill by means of welded stud shear connectors. This construction acts in a similar way to doubly reinforced concrete elements but the flexibility of connection between the steel plates and concrete gives rise to interface slip and additional overall element deflection. This paper presents a closed form solution for the analysis of simply-supported double skin composite beams. This method takes into account the flexibility of connection on both tension and compression faces and is extended to cover the effects of concrete cracking and non-linear connector behaviour using a step-wise linearisation technique. The analysis is compared against model and full scale experimental work that has been previously reported by the authors. It is concluded that the proposed method shows good correlation with real behaviour and may be reliably used for the analysis of simply supported double skin composite beams.

Shear Strength of Thin Flange Composite Specimens

Light gage steel is finding increasing use in load-carrying elements of structural systems. If very thin steel sections are to be used extensively in composite construction, experimental data on the behavior of the shear connector system are necessary. The purpose of this study was to explore the behavior of stud shear connector composite pushout specimens. Previous experimental studies of this composite system have been concerned with determining the behavior of the specimen when failure occurs either by pulling-out of the shear connector from the concrete or byshearing of the connector. If very thin steel flanges are used, it must be expected that failure could be controlled by pullout of the connector from the steel flange. The tests reported here examined the behavior of thin flange push-out specimens with 0.5, and 0.75 in. diameter welded stud shear connectors. The line defining the shift in failure mode from stud shear to flange pull-out is located.