Stud Shear Connectors Research Articles

Economic construction management of composite beam using the head stud shear connector with encased cold-formed steel built-up fix beam via efficient computer simulation

With regard to economic efficiency, composite fix beams are widely used to pass longitudinal shear forces across the interface. The current knowledge of the composite beam load-slip activity and shear capability are restricted to data from measurements of push-off. Modelling and analysis of the composite beams based on Euro-code 4 regarding to shear, bending, and deflection under differing loads were carried out using Finite Element through an efficient computer simulation and the final loading and sections capacity based on the failure modes was analysed. In bending, the section potential was increased by an improvement of the strength in both steel and concrete, but the flexural and compressive resistance growth is very weak (3.2% 3.1% and 3.0%), while the strength of the concrete has increased respectively from 25 N/mm2 to 30, 35, and 40 N/mm2 compared to the increment of steel strength by 27% and 21% when it was raised from 275 to 355 and 460 N/mm2, respectively. It was found that the final flexural load capacity of fix beams was declined with increase in the fix beam span for both three steel strength. The shear capacity of sections was remained unchanged at constant steel strength and different length, but raised with final yield strength increment of steel sections by 29%, and 67% when it was raised from 275 N/mm2 to 355 N/mm2 and 460 N/mm2, respectively.

Experimental Study on an Innovative Shear Connector in Steel-UHPC Composite Structure

In order to improve the stiffness and shear bearing capacity of steel-UHPC composite bridge, an innovative shear connector named arc-shaped reinforcement shear connector was proposed and compared with the stud and perforated bar steel plate shear connector using the static push-out test. Considering shear connector diameter, a total of ten push-out specimens for five groups were designed. The results indicated that the failure modes and failure mechanism of the arc-shaped reinforcement shear connectors were significantly different from stud shear connector and perforated bar steel plate. Obvious failure characteristics such as crack and reinforcement were not observed for the arc-shaped reinforcement specimens except for fine cracks on the top of one specimen, but these were observed for the others two types of shear connector. The relative slip value of arc-shaped reinforcement shear connector at the maximum load was the smallest and less than 1 mm in three types of shear connectors. The stiffness and shear bearing capacity of arc-shaped reinforcement were higher than those of stud and perforated bar steel plate under the same diameter. Increasing arc-shaped reinforcement diameter could improve significantly static behavior of shear connector. When the diameter of arc-shape reinforcement was increased from 8 mm to 12 mm, the ductility factor, stiffness, and shear bearing capacity of arc-shaped reinforcement shear connector were improved by 174.32%, 214.76%, and 54.2%, respectively. A calculation method of shear bearing capacity was proposed by the least square method and multiple regression analysis and agreed well with the test result.

Study on the shear performance of adhesive shear connectors in push-out tests

This paper introduces the adhesive shear connector aiming to remedy the defects of traditional mechanical shear connectors, such as stress concentration, discontinuous shear stress transmission and welding residual stress. To study the shear behavior of such connectors, the push-out tests of two groups of adhesive shear connector specimens (6 in total) were designed and completed, in which the adhesive materials are epoxy resin and magnesium phosphate cement (MPC) respectively. During the whole process of loading, the stress–strain curve, stress-slip curve and failure modes were obtained. In addition, the calculation method of predicting the ultimate shear bearing capacity of adhesive shear connectors was also explored. The results show that the shear strength of epoxy resin shear connector is higher than that of MPC one. The average shear strength of epoxy resin shear connectors is about 4.07 MPa, which is higher than that of the traditional stud shear connectors which is 3.0 MPa, indicating that epoxy resin shear connectors have the same interface shear capacity as traditional stud shear connectors. The failure mode of epoxy resin shear connectors is mainly the strength failure of concrete or adhesive layer, while the failure mode of MPC shear connectors is mainly the debonding failure between binder and steel. Suggestion for further study is that metal shear connectors can be used in combination with the adhesive shear connectors so as to make full use of the advantages of both.

Numerical Analysis on Shear Behavior of Grouped Head Stud Shear Connectors between Steel Girders and Precast Concrete Slabs with High-Strength Concrete-Filled Shear Pockets

Abstract This study numerically investigated the shear behavior of novel composite shear connectors, which consisted of grouped head studs embedded in high-strength concrete-filled (HSC-filled) she...

Numerical Simulation of Composite Beam Subjected to Harmonic Force Vibration

Simply supported steel and concrete composite beams connected by a number of headed stud shear connectors were adopted considering the existence of interface slip under the effect of forced vibration. ANSYS software is used to carry out the finite element simulation. Static load was applied first then different load cases of harmonic loadings were applied. The comparison between available experimental data and the obtained results from the numerical analysis proves the reliability of the developed model. The analysis results confirm that the shear connection degrees are a significant index related to the longitudinal shear ability and the overall flexure stiffness of the composite beam. The increase of average slip and mid-span deflection are mostly affected by the static load and with a little significant under dynamic load, whereas, the slip amplitude is mostly affected by the dynamic loading amplitude. The magnitudes of deflection rely on the frequency range and amplitude of loads and the value of frequency reflects the magnitude of applied load that make the deflection vary with the applied loads.

Experimental and numerical study of an innovative OMEGA-shaped connector for composite beams

Shear connectors in composite beam are used to ensure proper connection between concrete slab and steel beam. Headed stud shear connectors are the types most commonly used in composite constructions. Despite its popularity, this type of connectors has presented some drawbacks, notably its installation technique which demands many requirements. Recently, several shear connectors have been developed as an alternative to studs. The aim of the present paper is to present a study of a new type of OMEGA-shaped connector that is easy to design, fabricate and install. The geometry of the connector proposed allows good concrete confinement and provides high flexural stiffness. Experimental push-out tests have been carried out on OMEGA connectors and on headed studs to study their strength, ductility and failure mode. A comprehensive comparison between the two types of connector was established, which showed that the OMEGA connector proposed provides greater strength against shearing and uplifting. Thus, it can be used as an alternative to the conventional connector (headed studs) used in composite steel-concrete beams. The finite element models (FEM) of the push out test were developed using Abaqus software to conduct a parametric study on various dimensions of the OMEGA connector and different concrete strengths to evaluate their influences on the shear capacity and failure mechanism of the steel-concrete connection. It was concluded that the shear strength and failure mode of the OMEGA connector was relatively affected by increasing the shear area and concrete compressive strength, without significant impact on connection ductility. Based on the results obtained from the parametric study, a general equation for predicting the shear strength of the OMEGA connectors was introduced.

Assessment of composite beam performance using GWO–ELM metaheuristic algorithm

Composite beams (CBs) include concrete slabs jointed to the steel parts by the shear connectors, which highly popular in modern structures such as high rise buildings and bridges. This study has investigated the structural behavior of simply supported CBs in which a concrete slab is jointed to a steel beam by headed stud shear connector. Determining the behavior of CB through empirical study except its costly process can also lead to inaccurate results. In this case, AI models as metaheuristic algorithms could be effectively used for solving difficult optimization problems, such as Genetic algorithm, Differential evolution, Firefly algorithm, Cuckoo search algorithm, etc. This research has used hybrid Extreme machine learning (ELM)–Grey wolf optimizer (GWO) to determine the general behavior of CB. Two models (ELM and GWO) and a hybrid algorithm (GWO–ELM) were developed and the results were compared through the regression parameters of determination coefficient (R2) and root mean square (RMSE). In testing phase, GWO with the RMSE value of 2.5057 and R2 value of 1.2510, ELM with the RMSE value of 4.52 and R2 value of 1.927, and GWO–ELM with the RMSE value of 0.9340 and R2 value of 0.9504 have demonstrated that the hybrid of GWO–ELM could indicate better performance compared to solo ELM and GWO models. In this case, GWO–ELM could determine the general behavior of CB faster, more accurate and with the least error percentages, so the hybrid of GWO–ELM is more reliable model than ELM and GWO in this study.

Parametric study of innovative bolted shear connectors using 3D finite element modelling

This paper describes an extensive numerical analysis and parametric studies conducted to evaluate the performance of shear connectors as a key component in the design of composite beams. The shear connector is essentially used to transfer shear forces across steel beams and concrete slabs in composite structures. However, conventional methods which rely mainly on the welded stud shear connector are not as efficient in terms of recycling and reusing building components. Therefore, to address the issues of deconstruction and materials reuse and to improve the structural performance of the composite beams, bolted shear connectors have been developed to replace the conventional welded stud. In order to further study their behaviour, the structural performance of the bolted shear connectors were simulated and compared with the welded studs using Abaqus software. A tridimensional numerical model was validated using previously conducted experimental tests and was used as a reference for the parametric study. Height to diameter ratio, friction coefficient of steel-concrete interface, and concrete strength were selected as the main variables for the parametric study, along with the effects of the bolt-hole clearance. The results of numerical simulation were used to develop shear stress and ductility criteria of the innovative shear connector for design rules. The results of parametric studies also showed that the load carrying capacity of composite beams using the bolted shear connectors is influenced by the bolt's height, the friction coefficient of contact surfaces and the concrete strength.

Theoretical Study on the Influence of Welding Collar on the Shear Behavior of Stud Shear Connectors

Arc stud welding will melt the root of the stud to form a welding collar. For the purpose of exploring the influence of welding collar, numerical method is adopted for the theoretical analysis on shear resistance of the stud under several groups of different welding collar parameters. Firstly, the shear resistance between whether the headed studs considering the welding collars or not is compared. Then, the radius and height parameters of welding collar are changed. Finally, the increment ratio of bearing capacity by welding collars with the same height-diameter ratio is taken into consideration. Experimental data from three push-out test are adopted to validate the accuracy of the numerical method. The results show that the welding collar changes the yield area at the bottom of the stud. The height parameter has less influence than the radius. Under the condition that welding collars have the same height-diameter ratio, the improvement of shear resistance with different diameters roughly converges to 7.28%. The formulas of various countries show that at the height-diameter ratio of 0.25, the average value of bearing capacity of welding collar in various specification approach 7.1% of formula value.

Experimental and numerical studies on the shear connectors in steel-concrete composite beams at fire and post fire exposures

Shear connectors are required to build composite (concrete and steel) beams. They are placed at the interface of concrete and steel to transfer shear and normal forces between two structural components. Such composite beams are sensitive to provide structural integrity when exposed to fire as they loss strength, stiffness, and ductility at elevated temperature. The present study is designed to investigate the shear resistance and the failure modes of the headed stud shear connectors at fire exposure and post-fire exposure. The study includes ordinary concrete and concrete with carbon nanotubes (CNTs) to build composite (concrete-steel) beams with structural steel. Experimental push tests were conducted on composite beams at ambient and elevated temperatures, such as 200, 400 & 600C. Moreover, push tests were performed on the composite beams after being exposed to 200, 400 & 600C. Push test results illustrated the reduction of ultimate shear capacity and stiffness of headed stud shear connectors as the temperature increased. Although similar values of ultimate shear were obtained for the headed stud connectors in both ordinary and CNT concrete, the CNT modified concrete reduced the concrete spalling and cracking compared to ordinary concrete and was observed to be effective at temperatures greater than 400C. All specimens showed a lower shear resistance at fire exposures compared to the corresponding post-fire exposures. Moreover, numerical simulation by Finite Element (FE) analyses were carried out at ambient temperature and at fire conditions. The FE analysis results show a good agreement with the experimental results. In the experimental studies, failure of all specimens occurred due to shear failure of headed stud, which was later validated by FE analyses using ABAQUS.

Evaluation of Effect of The Flexible Shear Connector Type Embedded in High And Normal Strength Concrete on Load-slip Relationship

Shear connectors resists shear force that developed between interface of concrete and steel and thenprevent pull – out failure. Stud shear connectors are commonly used and most of research focused on behavior of this type. It's useful to study behavior and efficiency of other types. This investigation is about the effect of different parameters on load-slip and stiffness of flexible shear connectors. Three parameters were considered in this investigation; strength of concrete (35.5 and 62 MPa); type of connector (stud, C-shape and L-shape) and type of connection between shear connectors and steel section. It was found that increasing the compressive strength led to decrease in slip while load increasing. Stiffness of connectors increased with increasing of compressive strength. The stud connectors found to be stronger than C-shape and L-shape connectors while C-shape is the weakest one. Finally using welding connection gave a higher load, lower slip and higher stiffness compared to epoxy regardless of type of connectors and strength of concrete.

Experimental investigation on composite beams under combined negative bending and torsional moments

In this study, straight composite steel-concrete beams were tested to investigate their mechanical performance under combined negative bending and torsional moments. Two specimens were used in this study, and different ratios between the applied negative bending and torsional moments were induced. Load and deflection relationships, strain development on the steel main girder and shear connectors (stud), and the slip development on the steel-concrete interface were recorded in the test and reported in this paper. The results indicate that increase of torsional moment will result in the significant decrease of the load-carrying capacities (e.g. yield load and ultimate load) of the specimens. It was also found that the normal strains of stud shear connectors in such beams are very large and non-negligible compared to their shear strains. In addition, the maximum interface slip was found occurring at around the 1/4 span, and the support conditions and serious crack of the concrete were considered to be the main causes. The research results obtained in this study can provide references for the design and analysis of steel-concrete composite beams subjected to the combined negative bending and torsional moments.

A study on structural performance of deconstructable bolted shear connectors in composite beams

An experimental study according to EC4 on deconstructable steel-concrete composite bolted shear connectors is carried out to investigate the effect of various bolt size, concrete strength, bolt strength and clearance size between the precast concrete slab and bolt on the static behaviour of this type of composite connection. Shear load capacity for the first bearing, average major slip at the first bearing, maximum shear load capacity per bolt, slip corresponding to the maximum shear load capacity, maximum average slip between the precast concrete slab and steel beam and failure modes are assessed. A total of 12 composite specimens were tested according to EC4 with different parameters using deconstrcutable bolted shear connectors. In addition, two steel-concrete composite connection specimens using welded headed stud shear connectors were tested as control specimens to determine the influence of prefabricated concrete panels and deconstructable friction-grip bolted shear connectors on the performance of the steel-concrete composite connection. The experimental results show that deconstrcutable steel-concrete composite bolted shear connectors have completely different behaviour compared to welded headed stud shear connectors. Furthermore, a 3D finite element model of the steel-concrete composite connection having precast concrete slabs and deconstructable bolted shear connectors was performed. Numerical model was verified against experimental results, and was shown to accurately simulate their observed structural behaviour.

Fatigue life prediction of rubber-sleeved stud shear connectors under shear load based on finite element simulation

Rubber-sleeved studs, which are headed studs wrapped with rubber sleeves, have been found to be prospective to overcome some challenges in the design of steel–concrete composite structures with ordinary stud shear connectors. A finite element-based approach was provided for the fatigue life prediction of rubber-sleeved stud shear connectors. After calculating the stress and strain state of the connector by finite element models, the fatigue crack initiation life was predicted based on the critical surface method, and fracture mechanics was adopted to predict crack propagation life. The prediction method was validated by fatigue push-out test results. The subsequent finite element parametric study revealed the effect of shear stress range, rubber sleeve height, and elastic moduli of rubber and concrete on the fatigue life of shear connectors. Further, fatigue life prediction formulas for ordinary stud and rubber-sleeved stud shear connectors were proposed for facilitating the engineering application. The reliability of these formulas was verified by comparing with S-N curves in the design codes and those obtained from fatigue push-out tests.

Bond Behavior in Flexural Members: Numerical Studies

Adhesive bonding has recently emerged as an alternative to shear stud connection in steel–concrete composite flexural members. Research on adhesive-bonded steel–concrete composite flexural members is in a preliminary stage, and the behavior of the bond layer in these structures is not well understood yet. A three-dimensional finite element model is developed and used to conduct the parametric investigations. The developed model is validated with experimental results available in the literature. The behavior of the bond layer is defined in terms of normal stress, normal strain, shear stress, and shear strain. Seven different parameters are studied regarding their effect on the behavior of the bond layer. The parameters include load proportion factor, longitudinal distribution of load, transverse distribution of load, width of concrete slab, depth of the concrete slab, Young’s modulus of the adhesive and transverse location of the adhesive fiber. Parametric investigations are carried out to establish the relevance of parameters in terms of their effect on the behavior of the bond layer. The most significant parameters are identified as load proportion factor, longitudinal distribution of load, and Young’s modulus of adhesive.

Shear stiffness of headed studs on structural behaviors of steel-concrete composite girders

Steel-concrete composite structures have been extensively used in building, bridges, and other civil engineering infrastructure. Shear stud connectors between steel and concrete are essential in composite members to guarantee the effectiveness of their behavior in terms of strength and deformability. This study focuses on investigating the shear stiffness of headed studs embedded in several types of concrete with wide range of compressive strength, and their effects on the elastic behavior of steel-concrete composite girders were evaluated. Firstly, totally 206 monotonic push-out tests from the literature were reviewed to investigate the shear stiffness of headed studs embedded in various types of concrete (NC, HPC, UHPC etc.). Shear stiffness of studs is defined as the secant stiffness of the load-slip curve at 0.5Vu, and a formulation for predicting defined shear stiffness in elastic state was proposed, indicating that the stud diameter and the elastic modulus of steel and concrete are the main factors. And the shear stiffness predicted by the new formula agree well with test results for studs with a diameter ranging from 10 to 30 mm in the concrete with compressive strength ranging from 22.0 to 200.0MPa. Then, the effects of shear stiffness on the elastic behaviors of composite girders with different sizes and under different loading conditions were analyzed, the equations for calculating the stress and deformation of simply supported composite girders considering the influence of connection

Load sharing mechanism between shear studs and profiled steel sheeting in push tests

Push tests as suggested in Eurocode 4 have been widely used to determine the shear strength of stud shear connectors. In the presence of profiled steel sheeting, however, the push load is jointly resisted by both types of components, i.e., shear studs and sheeting. As a result, the exact load carried by a shear stud remains unknown. This paper intends to study the load sharing mechanism between the shear studs and sheeting in push tests through the development of a three-dimensional finite element model. It is found that the sheeting itself can carry 20–65% of the push load when the thickness of the sheeting is in the range of 0.9–1.5 mm. Accordingly, the actual load resisted by the shear studs is much lower than the prediction of Eurocode 4, which does not exclude the strength contribution from the sheeting. A parametric analysis is conducted to check the influence of a wide range of parameters including sheeting orientation, stud position and layout, diameter and height of studs, concrete grade, rib height, sheeting thickness, yield stress of sheeting, and level of transverse loading on the load sharing between studs and sheeting in composite slabs with trapezoidal steel sheeting. Finally, the ultimate push load and the actual stud strength obtained from parametric analysis are compared with the predictions from Eurocode 4. The comparison indicates that the accuracy of Eurocode 4 in predicting the ultimate push load can be improved. Meanwhile, new models are required to predict the actual shear strength of studs.

Experimental Investigation of Steel Confinement of Clustered Large-Size Stud Shear Connector in Full-Depth Precast Bridge Deck Panel

The research focuses on investigating different types of steel confinements around a clustered large-size stud shear connector using in full-depth precast concrete bridge deck panel. The tests were based on Push-off test of two main groups of specimens: (1) the specimens with 4-stud shear connector where three different types of confinement were adopted including of O-ring confinement, Wire-mesh confinement, and L-angle confinement), and (2) the specimens with 8-stud shear connector where two different types of confinement were investigated including of Plate-ring confinement and L-angle confinement. The test results concluded that L-angle confinement type of the group of specimens with 4-Stud is the most sufficient type comparing between the different types of confinement in the same group. The maximum resistance was found at 41-ton, while as the displacement was found to be the most expansible and gradually reduced until the failure point. This means that the sign of failure can be noticeable prior to a collapse of the structure. For the group of specimens with 8-Stud, the resistance of this group was higher than the group of specimens with 4-Stud about 50 - 100% increase depending on each type of confinement. The maximum resistance was found for Plate-ring confinement type at 70-ton, which was agreed with the increment of the displacement about 20 - 50%. In comparison between specimens with 8-Stud, the Plate-ring confinement showed greater resistance and more relative displacement about 15% than the L-angle confinement.

Shear behavior of large stud shear connectors embedded in ultra-high-performance concrete

In this article, the static shear behavior of large-headed studs embedded in ultra-high-performance concrete was investigated by push-out test and numerical analysis. A total of nine push-out specimens with single and grouped studs embedded in ultra-high-performance concrete and normal strength concrete slabs were tested. In the testing process, only shank failure appeared without cracks occurring on the surface of ultra-high-performance concrete slab when the steel–ultra-high-performance concrete specimens reached ultimate shear capacity. The shear capacity of specimens with large studs embedded in ultra-high-performance concrete slab increased by 10.6% compared those in normal concrete, and the current design codes such as Eurocode4, AASHTO LFRD 2014, and GB50017-2003 all underestimate the shear capacity of such kind of steel–ultra-high-performance concrete composite structures according to experimental results. Numerical models were established using ABAQUS with introducing damage plasticity material model. The influence of stud diameter, concrete strength, thickness of clear cover, and spacing of studs on the static shear behavior was thoroughly investigated via parametric analysis. Based on the experimental and numerical analysis, the existence of wedge block and the decrease of axis force are beneficial for improving the shear capacity of stud shear connectors.

Third-point flexural test on concrete-filled rectangular tubular flange girders

The influence of shear stud connectors on the horizontal displacement brought about by the occurrence of shear stress at the interface between the rectangular steel tube and in-filled concrete on Concrete-filled Rectangular Tubular Flange Girders (CFRTFG) was investigated. As a composite structure, providing shear stud connectors allow stress transfer between steel and concrete which may result for the two (2) components to work as a single unit. Accordingly, a three-dimensional finite element software called SOLIDWORKS® was employed. Static linear analysis was performed using the finite element (FE) models to study the effect of shear stud connectors on the resulting stresses and slip on CFRTFGs. Results showed that the maximum slip occurred at CFRTFG without shear stud connectors while CFRTFG under full composite action had the least slip. Correspondingly, the maximum shear stress for both CFRTFG under full and partial composite action occurred at the shear stud connectors, while the maximum shear stress for CFRTFG without shear connectors occurred at the supports. Conducting finite element analysis using SOLIDWORKS® proved to be theoretically accurate as in the case of this study.