Stud Shear Connectors Research Articles

Behaviour of a new type of shear connector for steel-concrete composite construction

Abstract The objective of this study was to investigate the structural behaviour of a new type of shear connector developed known as the Embossed Steel Plate connector (ESP). The need for the development for a new type of shear connector was due to the advancement of composite structures which subsequently enhances the composite behaviour as the shear connectors plays an important role in predominating the bearing capacity of the composite structure as a whole. Therefore, this study attempted to explore the structural behaviour of the newly developed shear connector by conducting push out test in accordance with Eurocode 4. The test results were correlated with the conventional head stud shear connectors and the structural behaviour of ESP connector was evaluated from the load slip curves.

Static behavior of stud shear connectors in high-strength-steel–UHPC composite beams

High-strength structural steel and ultra-high-performance concrete (UHPC) are being researched in many countries to expand their potential for wider application in civil engineering. This study investigated the shear performance of stud connectors in high-strength steel (fy = 690 MPa)-UHPC composite beams. A total of 6 pushout specimens, classified into three groups, were tested under static load. The test parameters included the diameter (13 mm/19 mm) and layout of the studs (single-stud/grouped-stud). The grouped-stud specimens were studied for assembly construction in composite beams. Based on the experimental results, empirical formulae for the load–slip curve of single-stud and grouped-stud specimens were proposed. Experimental results indicated that the failure mode of all the high-strength steel-UHPC pushout specimens was stud shank failure. The diameter of the studs significantly affected their shear performance. The shear capacity and shear stiffness of studs with a 19 mm diameter were 82.4% and 46.0% greater than those of studs with a 13 mm diameter, respectively. The layout of the studs had little effect on their shear capacity, with a 2.7% difference in shear capacity between single-stud and grouped-stud specimens on average. However, the stud arrangement had a great effect on the shear stiffness per stud. When the studs were arranged in a group, the shear stiffness per stud was 19.6% lower than the single-stud specimen on average because of the group effect. Although the grouped-stud specimens take advantage of assembly construction, the shear stiffness per stud decreased in the grouped-stud specimens. It was found that high-strength steel has little effect on the shear performance of studs compared with normal steel in pushout specimens. However, UHPC significantly improves the shear capacity and shear stiffness compared with normal concrete, but the ductility become relatively poor because of the higher elastic modulus of UHPC. In this paper, a formula for calculating the shear stiffness of grouped-stud specimens is also proposed based on the energy equivalent model. The main reason for the group effect is thought to be the ineffectiveness of concrete between studs in shear resisting owing to the short distance of studs. Thus, the shear stiffness per stud decreased in the grouped-stud specimens.

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.

Static and Fatigue Behavior of Rubber-Sleeved Stud Shear Connectors as Part of Field-Cast Ultra-High Performance Concrete Connections.

Field-cast ultra-high performance concrete (UHPC) connections are an innovative and prospective solution for combining full-depth precast concrete decks and steel girders. However, previous studies show that the slip capacity of stud shear connectors embedded in UHPC cannot meet the requirements for ductile connectors by Eurocode 4, which can reduce the resistance of steel and concrete composite members. In this study, the rubber-sleeved stud shear connector, which is a composite of ordinary stud and rubber sleeve, was adopted for the field-cast UHPC connections. Push-out tests were conducted to investigate the static and fatigue behavior of the rubber-sleeved stud shear connector as part of field-cast UHPC connections. Results of static tests showed that the rubber-sleeved stud shear connector has sufficient deformation capacity and its slip capacity is 1.5 times that of the ordinary stud shear connector. Compared to ordinary stud shear connectors, UHPC with high strength and stiffness has a relatively small effect on improving the shear strength and stiffness of rubber-sleeve stud shear connectors. Results of fatigue tests showed that the rubber-sleeved stud shear connector in UHPC has similar fatigue behavior to that in normal strength concrete. Though UHPC improves the restraint to the stud deformation, the influence of rubber sleeves is still decisive in determining the fatigue behavior of rubber-sleeve stud shear connectors. In addition, based on the results of strain gauges at stud roots, it was found that the crack initiation process consumes a small proportion of the fatigue life of rubber-sleeved stud shear connectors, which is about 5%.

Numerical study of the behavior of bolted shear connectors in composite slabs with steel deck

Nowadays, conventional shear connectors used in the composite slab with steel deck are welded headed shear studs. If the structure reaches the end of its design life, repairing these connectors will cost a lot and cause significant environmental damage. In this paper, with a numerical study, welded shear stud connectors were replaced with new bolted shear ones and the effects of parameters, such as: concrete strength, different positions, heights and diameters of the shear connectors, and the type and thickness of the steel deck, as well as the effect of the reinforcement arrangement on the behavior of these connectors, are evaluated. Moreover, various failure modes are investigated and the results are compared to AISC equations provided for welded shear connectors, to calculate the shear capacity of new bolted connectors. The results show that these connectors could be a good alternative to welded shear studs.

Behaviour of blind bolt shear connectors subjected to static and fatigue loading

This paper focusses on the performance of bolted shear connectors embedded in concrete slab when subjected to static and fatigue loading. The static and fatigue capacities of shear connectors between concrete slabs and steel beams are important issues, as existing composite structures experience complex loadings during their functional working life. The conventional headed stud shear connector is the most common form of shear connection in composite construction; in contrast the high strength bolts are not commonly used as shear connectors. Among different types of bolted shear connectors, the ability of blind bolt shear connectors to be attached and detached from one side of a structure resulting in faster installation and reduce the environmental cost is attractive. Therefore, in this study stiffness, ultimate strength, and ductility of blind bolt shear connector were examined through static tests. Furthermore, high-cycle fatigue tests were conducted to develop a S-N curve for the blind bolt shear connectors. In addition, failure modes of this type of shear connector were identified in detail.

Structural behaviour of stud shear connections in composite floors with various connector arrangements and profiled deck configurations

This paper investigates the structural behaviour of stud shear connections in composite floors with various connector arrangements and profiled deck configurations. The numerical investigation adopts a number of advanced finite element models which have been carefully calibrated against standard push-out tests conducted by the authors. In order to capture the complex interactions that take place between the concrete and the headed shear studs, a number of distinctive load transfer mechanisms within the solid concrete and the profiled composite slabs are identified and discussed. Detailed parametric studies are then undertaken using the calibrated models for the purpose of quantifying the shear resistance and deformation characteristics for connections with various stud and deck arrangements. A configuration parameter β is proposed for use in conjunction with the reduction factor kt given in EN 1994-1-1 to incorporate the effects of installation positions of headed shear studs and trough widths of profiled decks as well as the presence of longitudinal stiffeners if any. It is shown that the values of β are in the range of 0.55 to 1.0, which are significantly smaller than those commonly allowed for in the design of stud shear connections in composite floors.

Experimental and numerical analysis of grouped stud shear connectors embedded in HFRC

To investigate the mechanical behavior of grouped stud shear connectors embedded in hybrid fiber reinforced concrete (HFRC), nine push-out tests were performed with various parameters including the spacing and number of studs, and a refined 3D nonlinear finite element (FE) model incorporating the constitutive model of HFRC was developed using ANSYS. Firstly, the test results were discussed and used to validate the standard FE model of push out tests. Secondly, a total of 17 FE models of grouped stud-HFRC shear connectors were analyzed with various parameters including the number of studs, the fiber volume fractions of HFRC and the spacing of stud. Finally, an equation considering the contribution of steel fiber (SF) and polypropylene fiber (PF) was proposed by the regression method to estimate the capacity of a single stud for grouped stud-HFRC shear connectors according to FE analysis and test results of this paper and other researchers.

Behavior of rubber-sleeved stud shear connectors under fatigue loading

The fatigue performance of the rubber-sleeved stud shear connector, which is a composite of ordinary stud and rubber sleeve, is not clear yet, which limits its application in steel and concrete composite structures subjected to fatigue loading. In this paper, fatigue push-out tests on nine shear connector specimens were conducted to provide insight into the influence of shear stress range and rubber sleeve height on the fatigue performance of shear connectors. Nominal shear stress-based fatigue strength curves for rubber-sleeved stud shear connectors were established. It was observed that the fatigue strength of shear connectors decreases with the rubber sleeve height. In addition, rubber sleeves with low stiffness lead to a larger relative slip growth rate of rubber-sleeved stud shear connectors. However, the static stiffness degradation laws of the ordinary stud and rubber-sleeved stud shear connectors are similar, and a unified static shear stiffness degradation model was established. Moreover, fatigue failure mechanism of rubber-sleeved stud shear connectors was analyzed. The results illustrated in this paper can provide reference for the fatigue design of rubber-sleeved stud shear connectors and support their application in steel and concrete composite structures.

Flexural behavior of steel-UHPFRC composite beams under negative moment

Only few studies have been reported on the flexural behavior of steel-ultra high performance fiber reinforced concrete (UHPFRC) composite beams subjected to negative moment. Addressing this limitation, this paper presents the experimental and analytical studies on the steel-UHPFRC composite beam. Two large-scale beams, including one made of normal-strength concrete (NC) slab and another consisted of UHPFRC slab, experienced four-point bending test to investigate their flexural behavior. In this study, the steel girders and NC/UHPFRC slabs were made composite by embedding the stud shear connections in the pockets that were preformed on the precast slabs. The experimental results showed that the use of UHPFRC slab increased the stiffness and improved the crack control capacity of the composite beam. In addition, the full composite action was achieved in both tested beams, evidencing the sufficiency of the stud shear connectors for the tested conditions. The flexural strength and crack width were calculated through simplified analytical approaches. Good agreement was achieved between the measured and computed values.

Restraint Performance of Stud Connection during Lateral-Torsional Buckling under Synchronized In-Plane Displacement and Out-of-Plane Rotation

AbstractGenerally speaking, steel beams are mechanically assembled with a concrete slab and stud shear connectors. The concrete slab works as a restraint against buckling instability such as latera...

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.

Behavior of grouped stud shear connectors between precast high-strength concrete slabs and steel beams

This study aims to examine the interface shear behavior between precast high-strength concrete slabs with pockets and steel beam to achieve accelerated bridge construction (ABC). Twenty-six push-out specimens, with different stud height, stud diameter, stud arrangement, deck thickness, the infilling concrete strength in shear pocket (different types of concrete), steel fiber volume of the infilling concrete in shear pocket concrete and casting method, were tested in this investigation. Based on the experimental results, this study suggests that the larger stud diameter and higher strength concrete promoted the shear capacity and stiffness but with the losing of ductility. The addition of steel fiber in pocket concrete would promote the ductility effectively, but without apparent improvement of bearing capacity or even declining the initial stiffness of specimens. It can also be confirmed that the precast steel-concrete composite structure can be adopted in practice engineering, with an acceptable ductility (6.74 mm) and minor decline of stiffness (4.93%) and shear capacity (0.98%). Due to the inapplicability of current design provision, a more accurate model was proposed, which can be used for predicting the interface shear capacity well for specimens with wide ranges of the stud diameters (from13 mm to 30 mm) and the concrete strength (from 26 MPa to 200 MPa).

Numerical study on the deformation behavior of steel concrete composite girders considering partial shear interaction

The present paper focuses on the study of deformation behavior of steel concrete composite (SCC) girders with partial shear interaction. The main objective of this work is to bring out the relative significance of the partial shear interaction with respect to full interaction, which has been addressed with the help of parametric study considering various influencing parameters such as, degree of shear connection, span length, type of loading, distribution of shear stud connectors, geometry of steel girder, yield strength of structural steel and concrete grade. The parametric study has been carried out using a simplified numerical modelling technique with the help of commercially available finite element software SAP2000. The numerical modelling involves simulation of composite action between the concrete deck and the steel girder in the SCC girder, which has been carried out by using various elements such as, beam elements, rigid link elements and spring elements. Further, a comparative study has been carried out to study the accuracy of numerical model with the available analytical models. The results of the numerical model are also compared with the results of the equations given in several national codes to calculate deflections, to study the efficacy of the codal provisions. It is seen that the various aforementioned parameters have considerable influence on the deformations of SCC girders. It is also seen that the change in distribution type of shear stud connectors considerably reduce their number without significantly affecting the deformations of SCC girder.

EXPERIMENTAL STUDY ON BEHAVIOUR OF SHEAR CONNECTORS IN MOMENT RESISTANCE OF STEEL COMPOSITE JOINTS

AbstractThis paper presents an experimental investigation on the behavior of steel stud connectors in steel composite joints with precast hollowcore slabs in resisting the static bending moment. An experimental program including 5 flexural tests was carried out, and the failure modes of the studs, as well as the shear capacity of stud connectors are investigated. Their contribution to the overall joint moment capacity were studied in depth. The pertinent design recommendation in shear stud design for enhance the moment capacity of the composite joints are also proposed. The testing results and design recommendations presented in this paper can provide basic for future design of composite joints using shear stud connectors with precast slabs

ANALYSIS OF THE EFFECT OF CONCRETE STRENGTH IN EMBEDDED SHEAR CONNECTORS OF STEEL‐CONCRETE CORRUGATED WEB COMPOSITE BRIDGES THROUGH PUSH‐OUT TESTS

AbstractTraditionally in steel‐concrete composite bridges, the structural elements with different materials are work together with headed stud shear connectors welded to the top flange of the steel beam. The application of trapezoidal corrugated web embedded in the concrete slab provides an alternative for steel‐concrete composite and hybrid structures, however requires new solutions for shear connectors. The paper focusing on the corrugated web type composite and hybrid girders with embedded shear connector called concrete dowel. The paper provides an overview of the push‐out test program performed in the Structural Laboratory of the Department of Structural Engineering in BME.

Different load bearing mechanisms in headed stud shear connectors for composite beams with profiled steel sheeting

Different load bearing mechanisms in headed stud shear connectors for composite beams with profiled steel sheeting

Full scale experiments on splitting behaviour of concrete slabs in steel concrete composite beams with shear stud connection

This paper presents the results of 15 push-off tests to determine, with a high degree of precision, the longitudinal splitting characteristics of a concrete slab in a novel steel-concrete composite beam with headed shear stud connectors. A modified test rig was developed, instead of the standard push-off test rigs. Both monotonic and cyclic loadings were considered. The experiments allowed the exploration of several currently unknown effects of various loads on components of steel-concrete composites, such as transverse loading and low-level cyclic loading on shear stud capacity. The results allowed the splitting failure mode to be characterised in unprecedented detail. It was found that for the case of cyclic loading, when many cycles were applied, it did not lead to premature failure of the composite beam, but instead increased the capacity of the beam against longitudinal splitting. This is significant for composite members under variable loading, such as floor supporting beams in car parks. It was also shown that the transverse compression forces across the base of the studs would increase the capacity of the beam against longitudinal splitting. Also studied were the differences and limitations of EuroCode 4 and New Zealand (NZS) standards and their effects on composite beam failure characteristics. It was shown that the presence of anti-splitting reinforcement would result in a gradual loss of load carrying capacity, compared to a sudden loss when not present. Even with sufficient side cover from the stud to the edge of the concrete, following the NZS standard, longitudinal splitting in composite beams continues to be observed.

Stress Redistribution of Headed Stud Connectors Subjected to Constant Shear Force

In order to evaluate the stress concentration of stud shear connectors considering creep effect of concrete, finite element analysis of the push-out specimen is carried out. The rate of creep method is used in the solid model to reflect the creep property of concrete. Local bearing stress and splitting stress of concrete are analyzed. The stress concentration of steel beam and stud near the weld toe are obtained. Results show that owing to the creep effect of concrete, the local stresses of the stud are redistributed, even under constant shear force. The stress concentration factor (SCF) of concrete bearing stress in front of the weld collar decreases by about 52%, while the bending deformation of the stud increases due to the stress redistribution given 10 years of creep time. SCF at the weld toe of steel beam increases about 1.5 times of short-term, and SCF of stud shank increases about 3 times. The stress concentration at the root of studs become more obvious under constant shear force due to concrete creep, which is adverse for the long-term behavior of studs in the normal service stage.

Experimental study on time-dependent deformation of hybrid steel–PRC girder with headed stud shear connections under sustained loading

In a hybrid girder, the connections at the steel–prestressed reinforced concrete (steel–PRC) junction must be designed to resist steel–concrete interfacial tensile and shear forces. Headed stud shear connections are most commonly and widely used for such an application. In Japan, the Japan Road Association specifies a stud capacity that is 0.12, 0.13, and 0.22 times those of the American Institute of Steel Construction, Japan Society of Civil Engineers, and EURO code specifications, respectively. Hence, in Japan, the existing design method uses less than 50% of the actual nominal shear capacity of connectors. Owing to a low design shear force, the influence of sustained loads has not yet been considered nor studied comprehensively. Moreover, in a hybrid girder, the prediction of the time-dependent deformation behaviour under sustained loading is crucial for ensuring serviceability; however, few studies have focused on this subject. Five scaled-down hybrid steel–PRC girder specimens of a real bridge with headed stud connections were tested under sustained and static loads. The time-dependent deformation behaviour was sensitive to the exposure time, previous loading history, prestress level, concrete strength, and creep and shrinkage phenomena. The results of this study provide an important basis and reference data for designing such girders while considering their long-term response with time effects.