Shear Stud Spacing Research Articles

Experimental study on the effect of partial shear studs layout on flexural behavior of steel-concrete composite beams

In steel-concrete composite beams, partial shear connection offers advantages including greater ductility and lower cost. However, partial shear connection constraints on composite beam structural performance, such as reduced beam stiffness, increased steel-concrete interface slip, etc., should not be neglected. Several researches have revealed that shear connector layout is one of the main approaches to limit partially composite beam vulnerability. Shear connector layout optimization has not been completely investigated experimentally, and its effect on composite beam structural performance is still unknown. This paper focusses on the experimental study of the effect of shear connectors layout on the flexural performance of composite beams. It reports the optimization of the layout of shear connectors based on blocked distribution of shear connectors laid in a single row, while concentrating the highest number of shear studs towards the supports of a simply supported composite beam. A fully composite beam with normal layout of shear studs was tested as control specimen, while the rest of the beams used partial shear connection (η = 0.5). Beams with partial shear connection had 3 different layouts of shear studs. The first had uniformly distributed shear studs, and the rest had shear studs laid out in 2 and 3 blocks each of uniform spacing respectively. The results showed that the beam with 3 blocks layout each of equal spacing of shear studs had the closest best structural performance to the fully composite beam and had better ductility than the latter.

Study on headed shear studs influencing the interfacial bond behaviour in CFST columns

AbstractThe performance of concrete‐filled steel tubular (CFST) columns with headed shear studs under push‐out loading has been investigated. The primary objective of the research programme was to investigate the bond behaviour between the steel tube and the infill concrete core of the square CFST column. A numerical investigation has been carried out using the commercially available finite element software. For the simulated numerical models, they have been initially validated with existing experimental results. The validations were made in terms of failure modes, bond strength‐slip curves and the initial stiffness. The validated models were further used to carryout parametric studies. The parameters studied include, vertical spacing of shear studs, horizontal spacing of shear studs, and CFST cross‐section slenderness. From the investigation, it is observed that with reduced vertical spacing of studs, the bond strength increases significantly. Specimens having horizontal spacing of studs as width/4 has more bond strength than specimen with horizontal spacing of width/2 and 0. For specimens with reduced vertical and horizontal spacing of studs though leads to higher bond stress, but also drops suddenly due to loss of contact between the stud and concrete. Therefore, 70% of the peak stress value may be considered as the achieved bond stress, as this stress value sustains for higher slip values. Lastly, as the column cross‐section slenderness reduces, there is a trend in increase in interfacial bond strength.

Experimental and numerical study on seismic behavior of partially steel-reinforced concrete beam-to-steel tube column joint

Steel-reinforced concrete (SRC) beams are commonly used in the transfer structures of high- and super-high-rise buildings since concrete-encased steel elements have good resistance to buckling and seismic performance. However, the full-length steel shapes utilized in SRC beams are ineffective and pose many construction challenges. This study proposes a new steel-reinforced concrete beam-square steel tube (SST) column joint in which the SRC beam is embedded with a partial-length steel shape. Experimental tests are conducted on three joint specimens with varying cross-sectional dimensions of the SRC beam and lengths of the steel shape. The experimental results show that all the specimens exhibit good deformation, load-carrying capacity, and stable hysteresis responses. The three specimens demonstrate a considerable strength drop at drifts exceeding 5%. Besides, significant plastic deformation occurred at the column base region and in a limited region of the steel beam flange near the beam-column joint. Finite element models are developed to study the effects of single-side steel length, shear stud spacing, and thickness of beam concrete cover on the seismic performance of the proposed joint. The elastic deformations that caused the total column drift were theoretically analyzed. The predicted joint initial rotational stiffness using the proposed equation agrees well with the test and numerical results. The study’s limitations are also discussed.

Experimental study, finite element simulation and theoretical analysis on failure mechanism of steel–concrete-steel (SCS) composite deep beams with UHPC

Configurations of steel faceplate (SP) and filled concrete (FC) are the main concern issue in steel- ultra-high performance concrete (UHPC) -steel (SUS) composite deep beams, which have important effects on failure modes, mechanical behaviors and interfacial slip. This paper aims to quantify the relationship between failure modes and configurations of SP. Results can be used to explore the failure mechanism and propose the theoretical models of SUS composite deep beams. 6 SUS composite deep beams were measured. Results indicate that SUS composite deep beams with different configurations of SP and FC, exhibit different failure modes, including shear without slip failure, slip failure and flexural without slip failure. Influence mechanism of SP, FC, spacing of shear studs on failure modes, mechanical behaviors and interfacial slip was explored. Failure mechanism was revealed by a modified Strut-and-Tie model. Subsequently, finite element (FE) models of SUS composite deep beams were developed to obtain the width of concrete diagonal strip, and configuration relationship between SP and FC. Based on the test results and FE results, the theoretical models of SUS composite deep beams corresponding to different failure modes were deduced and validated, considering the interfacial slip between SP and FC.

Experimental and numerical investigations into the compressive behaviour of circular concrete-filled double-skin steel tubular columns with bolted shear studs

Eight medium-length circular concrete-filled double-skin steel tubular (CFDST) columns were examined under axial compression to evaluate the influence of bolted shear studs on the axial performance of CFDST columns. The specimens comprised six columns with bolted shear studs with longitudinal spacings of 100 mm, 75 mm, and 50 mm, and two control columns without bolted shear studs for comparison. The investigated parameters were the failure mechanisms, load-displacement curves, initial axial stiffness, compressive strength, toughness, ductility, residual strength, as well as load-strain responses. Besides, a finite element (FE) model was developed and validated against experimental results to further investigate the performance of columns. The test results demonstrated that the bolted shear studs avoided shear failure and significantly increased the ductility of the specimens. Reducing the bolted shear stud spacing reduced the intensity of local buckling in the outer tube and improved the confinement effect. Additionally, the confinement effect provided by the outer tube was remarkably improved by introducing the bolted shear studs.

Composite action on web-post buckling shear resistance of composite cellular beams with PCHCS and PCHCSCT

This paper aims to study the composite action on web-post buckling (WPB) resistance of composite cellular beams with precast hollow core slab (PCHCS) units and with precast hollow core slab units with concrete topping (PCHCSCT). Geometrical and material non-linear analyses are performed. A parametric study is developed, varying the opening diameter, the web-post width and the shear stud spacing, with single and double row. It was found that the models with double row of shear studs showed global shear resistance greater than or equal to the models with only one row. For models with PCHCS, there was a reduction in global shear resistance in some analyses due to the absence of shear studs in the second opening, close to the support. For PCHCSCT models, there was an increase in the global shear resistance, in comparison with PCHCS models. However, in most of these models, shear stud rupture occurred. Finally, the WPB models were compared with a simplified equation that takes into account the global shear resistance due to buckling, composite action and Vierendeel bending. The average, standard deviation and variation value of the ratio between the analytical and numerical models were 0.833, 12.47% and 1.55%, respectively.

Ultimate capacity and failure mechanism of SCS and S-UHPC composite deep beams: Test and modeling

In this study, a type of steel–concrete–steel (SCS) composite deep beam with ultra-high-performance concrete, named S-UHPC deep beam, was developed. Eight simply supported deep beams, including three SCS deep beams and five S-UHPC deep beams, were tested under static loads. The effects of different parameters (including the shear span ratio, concrete type, and shear stud spacing) on the ultimate capacity, ductility, and interfacial slip of the specimens were explored. Moreover, the observed failure modes were categorized into shear failure without slip, slip failure, and flexural failure with the snapping of steel fibers. To analyze the failure mechanism systematically, finite element (FE) models of the specimens were established and validated. By analyzing the FE simulation results on the compressive damage and stress distribution of the filled concrete, the von Mises stress distribution of shear studs, and the equivalent plastic strain distribution of the bottom steel faceplate, the failure mechanism of the specimens with the observed failure modes was simplified as a modified Strut-and-Tie model. Based on the force transfer analysis of the modified Strut-and-Tie model, a slip coefficient was deduced to quantify the composite action and provide theoretical supports for the reasonable design of shear connectors. Theoretical models of SCS deep beams and S-UHPC deep beams with different failure modes were presented to predict the ultimate capacity.

Improved stud layouts for steel-plate–concrete walls subject to blast load

An analytical study using a non-linear finite-element method was carried out to evaluate the effect of the shape and spacing of shear studs on the behaviour of steel-plate–concrete walls subject to blast loads. The size of the analytical model was determined by reference to an existing literature review and code requirements (Kepic-SNG). The analytical model was validated against experimental results. The behaviour of a wall subject to blast loading was then analysed for various stud spacings and shapes. As found in previous research, the maximum deflection increased as the spacing of studs increased and the time when the maximum deflection occurred was delayed. Improved studs were found to be effective in reducing displacement when arranged at lengthwise spacings of 100 mm or more.

Numerical and theoretical analysis of seismic behaviour of CFDSP composite shear walls

In the present study, the seismic behaviour of concrete-filled double-steel-plate (CFDSP) composite shear walls was numerically and theoretically investigated. Finite element (FE) models of CFDSP composite shear walls were designed, validated, and analyzed. Based on the FE models, the influence of the width-to-thickness ratio, height-to-width ratio, axial compression ratio, thickness of steel plates, number of stiffeners and spacing of shear studs on the seismic behaviour of CFDSP composite walls was also investigated. The failure mode, hysteretic curve, skeleton curve, stiffness, shear-bearing capacity, and ductility of CFDSP composite shear walls are discussed. It was revealed that CFDSP composite shear walls make full use of the steel and concrete materials and exhibit excellent seismic performance. Additionally, a restoring force model for describing the hysteretic behaviour of CFDSP composite shear walls has been proposed and discussed. The predicted hysteretic curves obtained from the restoring force model are in good agreement with the test results. This research confirmed that CFDSP composite shear walls are suitable lateral resisting members of high-rise buildings.

Fire Resistance of Composite Beams with Restrained Superposed Slabs

To investigate the fire resistance of composite beams with restrained superposed slabs, three specimens were tested under uniformly distributed loads in a furnace. The effects of the thickness of the postcast top layer in superposed slabs and the spacing of shear studs on the structural behaviours of composite beams under fire were further examined. During the tests, the temperature distributions of the superposed slabs and steel beams as well as the displacements at their key positions were recorded and analysed. It was found that the temperature of the concrete superposed slabs decreased long their heights from the bottom. The most drastic change of the temperature along the slab cross section was found in the region with a distance of 40 mm to the slab bottom. The concrete superposed slabs could impose restraints to the steel beams due to their incompatible deformations. Cracks were developed on the top surfaces of the specimens and the superposing interfaces between the precast slabs and postcast top layers were not broken. Through the comparisons of different specimens, the spacing of shear studs could have a significant effect on the fire resistance of composite beams, especially for their deformation recovery capacities. In contrast, the effect of the thickness of the postcast top layers was negligible. ABAQUS was employed to simulate the temperature fields and deformation behaviours of composite beam specimens based on a sequenced thermomechanical coupling analysis. The numerical results agreed well with the experiment data, which validated the developed numerical model.

Ultimate strength behavior of steel plate-concrete composite slabs: An experimental and theoretical study

Steel plate-concrete composite slabs provide attractive features, such as more effective loading transfer, and more cost-effective stay-in-place forms, thereby enabling engineers to design more high-performance light structures. Although significant studies in the literatures have been directed toward designing and implementing the steel plate-concrete composite beams, there are limited data available for understanding of the composite slabs. To fill this gap, nine the composite slabs with different variables in this study were tested to unveil the impacts of the critical factors on the ultimate strength behavior. The key information of the findings included sample failure modes, crack pattern, and ultimate strength behavior of the composite slabs under either four-point or three-point loading. Test results showed that the failure modes varied from delamination to shear failures under different design factors. Particularly, the shear stud spacing and thicknesses of the concrete slabs significantly affected their ultimate load-carrying capacities. Moreover, an analytical model of the composite slabs was derived for determining their ultimate load-carrying capacity and was well verified by the experimental data. Further extensive parametric study using the proposed analytical methods was conducted for a more comprehensive investigation of those critical factors in their performance. These findings are expected to help engineers to better understand the structural behavior of the steel plate-concrete composite slabs and to ensure reliability of design and performance throughout their service life.

Shear Capacity of Open Sandwich Steel Plate‐Concrete Composite Slab: Experimental and Analytical Studies

Considering that the fixed crack model by default of the general finite element software was unable to simulate the shear softening behavior of concrete in the actual situation, a rotational crack model based on the modified compression field theory developed by UMAT (user material) of ABAQUS software was proposed and applied to the nonlinear analysis, and a numerical simulated model for the steel‐concrete composite slab was built for shear analysis. Experimental studies and numerical analyses were used to investigate the shear load‐carrying capacity, deformation, and crack development in steel plate‐concrete composite slab, as well as the effects of the shear span ratio and shear stud spacing on the shear performance and the contribution of the steel plate and the concrete to the shear performance. Shear capacity tests were conducted on three open sandwich steel plate‐concrete composite slabs and one plain concrete slab without a steel plate. The results indicated that the shear‐compression failure mode occurred primarily in the steel plate‐concrete composite slab and that the steel plate sustained more than 50% of the total shear force. Because of the combination effect of steel plate, the actual shear force sustained by the concrete in the composite slab was 1.27 to 2.22 times greater than that of the calculated value through the Chinese Design Code for Concrete Structures (GB 50010‐2010). Furthermore, the shear capacity of the specimen increases by 37% as the shear stud spacing decreases from 250 mm to 150 mm. By comparing the shear capacity, the overall process of load deformation development, and the failure mode, it was shown that the simulation results corresponded with the experimental results. Furthermore, the numerical simulation model was applied to analyze the influence of some factors on composite slab, and a formula of shear bearing capacity of slab was obtained. The results of the formula agreed with the test result, which could provide references to the design and application of steel plate‐concrete composite slab.

Bond-slip effect in steel-concrete composite flexural members: Part 2-Improvement of shear stud spacing in SCP

The use of shear studs usually placed in the form of mechanical shear connectors makes it possible to adopt composite steel-concrete structures in various structures, and steel-concrete plate composite (SCP) is being seriously considered for the installation of storage tanks exposed to harsh environments. However, manufacturing of SCP must be based on the application of existing design guidelines which require very close arrangement of shear studs. This means that the direct application of current design guidelines usually produces very conservative results and close arrangement of shear studs precludes pouring concrete within exterior steel faceplates. In this light, an improved guideline to determine the stud spacing should be introduced, and this paper proposes an improved ratio of the stud spacing to the thickness of steel plate on the basis of numerous parametric studies to evaluate the relative influence of the stud spacing on the stability of the SCP.

Shear failure mechanisms of SCS sandwich beams considering bond-slip between steel plates and concrete

The steel-concrete-steel (SCS) sandwich structure has been proposed for containment buildings in third-generation nuclear power plants. In this paper, 27 static tests on SCS sandwich beams (by the authors and others) are adopted serially to summarize the failure modes and explore the failure mechanisms of SCS sandwich beams with different bond-slip conditions between the steel plate and concrete. Further, a three-dimensional finite element (FE) model is developed to simulate the ultimate strength of SCS sandwich beams under different failure modes. The accuracy of the developed FE model in predicting ultimate strength, cracking behaviours and bond-slip behaviours is verified by static tests. Based on the validated FE model, 65 numerical cases are calculated to investigate the effects of analytical parameters on the failure mechanism and ultimate strength of SCS sandwich beams under different bond-slip conditions. The analytical parameters include the steel plate ratio, shear span to depth ratio, spacing of shear studs and shear reinforcement ratio. In addition, theoretical models are proposed to predict the ultimate strength of SCS sandwich beams under different bond-slip conditions. The accuracy of the theoretical model is verified by comparison with current design codes for SCS sandwich beams.

Bending experiment on a novel configuration of cold-formed U-shaped steel-concrete composite beams

This paper discusses a novel configuration of rebar truss stiffened cold-formed U-shaped steel-concrete composite beams (RCUCB). The open steel U-section is stiffened by a rebar truss. The interface between concrete slab and lower part (including steel U-section, encased concrete, and reinforcement) is enhanced with uniformly distributed inverted U-shaped rebars. The reinforcement is installed at the bottom of the lower part to control the concrete longitudinal deformation. A flexural experiment on ten specimens was conducted considering reinforcement ratio, steel ratio, beam depth, and shear stud spacing (at the bottom of steel U-section). Typical flexural failure mode was observed and the rebar truss and inverted U-shaped rebar were found to provide significant integrity for the RCUCB. Thus, the RCUCB can achieve plastic bending capacity and excellent deformability. The mid-span deflection, plastification factor, and ductility factor of the RCUCB are up to L0/20, 2.08, and 24, respectively. An effective slab width of b + L0/3 may be chosen according to the strain distribution. The bending capacity calculated according to EC4 and JGJ 138-2016 agrees generally well with the test result. Finally, design details pertaining to the width to thickness ratio of bottom steel soffit, the height to thickness ratio of steel web, the transverse reinforcement ratio of concrete slab, and bottom longitudinal reinforcement are suggested accordingly.

Fire resistance of concrete-filled steel plate composite (CFSPC) walls

Concrete-filled steel plate composite walls (CFSPC walls) have recently emerged as promising alternatives to conventional reinforcement concrete shear walls due to the benefits of effective space use, less construction time/effort, and higher ductility. While the basic load carrying capacity and seismic performance of CFSPC walls have been receiving great attention, little work has been conducted so far on their fire performance. This paper aims to bridge the knowledge gap by performing 12 fire tests on CFSPC walls, where shear stud spacing, wall height, wall thickness, steel ratio, and fire scenario (uniform or single-sided fire) were considered as the main test parameters. For the uniform fire tests, the specimens exhibited reasonably good fire resistance, where the fire resistance time exceeded 2h. Three dominating failure modes were observed, namely, local buckling of steel plates (LB), severe cracking (‘tearing’) of the weld along the corner line of the wall (WC), and global instability (GI). For the specimens subjected to single-sided fire, minor local buckling of the heated steel plate accompanied by tie bar failure in the buckled areas were observed, but no further load bearing failure was induced by the end of the heating process. The fire resistance time, which exceeded 2.5h for the specimens exposed to single-sided fire, was governed by the ‘thermal insulation criterion’. After 2.5h of heating, some specimens lost their thermal insulation capacity. Based on the test phenomena, preliminary design recommendations are proposed, and future research directions are also outlined.

Seismic performance of composite plate shear walls

Nonlinear seismic responses of a 4-storey and 6-storey composite plate shear wall (C-PSW) are studied. A nonlinear finite element model which includes both material and geometric nonlinearities is used for this study. Nonlinear seismic analysis shows that composite plate shear walls, in high seismic region, behave in a stable and ductile manner. It has been observed that the boundary members and the reinforced concrete panel of C-PSW carry significant amount of shear which is not considered in design of C-PSW in AISC 341-10. The study also shows that design axial forces and moments in the boundary columns designed according to capacity design concepts are in good agreement with those of the nonlinear seismic analyses. A series of C-PSWs with different geometry are designed and analysed to evaluate the current period formula in building codes. It is observed that the current code predicts periods that are generally shorter than the periods obtained from finite element analysis. An improved simple formula for estimating the fundamental period of C-PSW is developed by regression analysis of the period data obtained from analysis of the selected C-PSWs. Finally, two equations for determining shear stud spacing and thickness of reinforced concrete panel for the C-PSWs are proposed.

Buckling behavior of double-skin composite walls: An experimental and modeling study

Double-skin composite (DSC) panels can offer high strength and robustness while improving the convenience of construction, with great potential for application in high rise buildings and nuclear power plants. In DSC panels, the stability of the outer surface steel plates are governed by the constraints of the in-fill concrete and the discrete shear connectors, i.e., the ratio of connector spacing (B) and surface steel plate thickness (t). In this paper, tests were performed on 10 specimens to assess the buckling behavior of DSC panels. The arrangement of the shear studs and the B/t ratio were varied in the tests. The results show that the arrangement and spacing of the shear studs can considerably influence the buckling shapes and loading capacity of the steel plates. Three-dimensional finite element (FE) models were developed to simulate the behavior of DSC panels subject to compression, and the FE results were found to be in good agreement with the observed buckling behavior during tests. A theoretical model based on Euler's equation was also proposed to predict the buckling stress of steel plates, and it showed reasonable agreement with the experimental measurements and FE results. The formula proposed in this paper can be used for determining the number or spacing of shear studs in DSC walls.

Stiffness and capacity of steel–concrete composite beams with profiled sheeting

The present study investigated the stiffness and capacity of steel–concrete composite beams with profiled sheeting by considering shear slip effects. Using an analytical method similar to that for common steel–concrete composite beams accounting for slip effects, the equivalent stiffness and elastic flexural capacity of steel–concrete composite beams with profiled sheeting were derived. A formula for ultimate flexural capacity of steel–concrete composite beams with profiled sheeting was also developed, which verified the applicability of the interpolation method suggested in the literature. Meanwhile, a coefficient γ was defined in this paper for considering the influence of the shear stud spacing on the shear stud capacity. Comparison with the measurements of the five specimens tested in the present study and other available test results shows that the proposed formulae predict results with a good accuracy.