Headed Stud Shear Research Articles

Nonlinear finite element analysis of simply supported composite beams stiffened with steel channel

A composite beam is an accumulation of differentmaterials so as to form a single unit to exploit the prominentquality of these materials according to their position within thecross-section of the composite beam. The present studyinvestigates the structural behavior of six simply supportedcomposite beams, in which a reinforced concrete T-beam isconnected together with a steel channel located at the bottomof a T-beam by means of headed stud shear connectors. Theused degrees of shear connection are (100%, 75%, 50%, and38%). Three dimensional nonlinear finite element analysis hasbeen used to conduct the numerical investigation for thegeneral behavior of beams which are subjected to central pointload. ANSYS 12.1 program code was used to estimate theultimate loads, deflections, stresses, strains, end slip. Concretewas modeled by brick element (SOLID65), while the steelchannel was modeled as a brick element (SOLID45). Two-nodediscrete elements (LINK8) are used to represent the steelreinforcement and shear connectors. The perfect bond between thereinforcing rebars and the concrete was assumed. The load onbeams was applied monotonically in increments up to failure.The reduction of the degree of shear connection from 100% to38% causes increasing of strain, mid-span deflection and endslip with an average of 3.95%, 13%, and 111% respectively,while the ultimate load decreases with an average of 7.3%. Inorder to observe the efficiency of the 3-D model, a comparisonwas made with available experimental work. Good agreementwas obtained throughout this work between the finite elementand available test results.

Behavior of Large-Scale Hybrid FRP–Concrete–Steel Double-Skin Tubular Beams with Shear Connectors

AbstractHybrid fiber-reinforced polymer (FRP)–concrete–steel double-skin tubular members (DSTMs) are a new form of hybrid members that consist of an outer tube made of FRP and an inner tube made of steel, with the space between them filled with concrete. The existing studies on hybrid DSTMs have been mainly focused on their use as compression members, with only a very limited number of studies on their use as flexural members [i.e., hybrid double-skin tubular beams (DSTBs)]. This paper presents the first ever experimental study on large-scale hybrid DSTBs with headed shear studs; the effect of an integrated deck is also examined. The main parameter examined in the experimental program was the section configuration. The test results show that both the DSTBs and the DSTB-deck unit possessed a very ductile response, and that the headed shear studs effectively reduced or eliminated slips between the steel tube and the concrete. This paper also presents a theoretical model based on conventional section analysi...

Performance of unprotected and protected cellular beams in fire conditions

This paper describes an experimental study at elevated temperatures on the behaviour of full-scale composite floor unprotected and protected cellular steel beams with intumescent coating having different size and openings shape. All beams were designed for a full shear connections between the steel beam and the concrete flange using headed shear studs in order to fail in by web-post buckling. In fire, the temperature distribution across a composite member is non-uniform, since the web and bottom flange have thin cross-sections and a greater exposed perimeter than the top flange. The deterioration of the material properties of the web will therefore become an important effect on the overall performance of the member in the event of fire. Fire resistance and protection of cellular beams has been very controversial concerning their behaviour in elevated temperatures, the fire protection material and the required thickness. Two failure temperatures were observed in the fire tests indicated that cellular beams failed by web post buckling and Vierendeel bending associated with the buckling of the web posts of the steel section. The finite element modelling software TNO-Diana was used to complete the numerical investigation. Comparison of the experimental and FEM results is presented and both are in good agreement. However the Euro code approach can be improved by using the correct material specification of the intumescent coating used.

Influence of Shear Connector Size on Ultimate Strength in Composite Construction with Cold-Formed Steel Channel Lipped Section

In conventional composite construction for buildings and bridges, Hot-Rolled Steel (HRS) section is well known to be used. The composite action is usually achieved by using conventional headed stud shear connectors. However, for Cold-Formed Steel (CFS) section, the use of headed stud shear connectors is not feasible as the section is very thin and incapable to be weld. Therefore, a suitable shear connection system of bolt and nut is proposed in this study by varying the size of the bolted shear connectors. This paper presents the prospect of using a bolt and nut as shear connector that could be well-suited with CFS section when integrated in Self-Compacting Concrete (SCC). The experimental test comprised of push-out and was conducted to determine the strength and ductility of the proposed bolted shear connectors as used in composite construction. Eight push-out test specimens of bolted shear connector size consist of M12, M14 and M16 of grade 8.8 were fabricated and tested to failure. The experimental results show that the bolted shear connectors used to possess good shear resistance capacity. Influence of varying the size of the bolted shear connectors was investigated. The results show that the size of bolted shear connectors influenced the ultimate strength capacity of the shear connectors significantly.

Flexurally-triggered punching shear failure of reinforced concrete slab–column connections reinforced with headed shear studs arranged in orthogonal and radial layouts

Shear strength of reinforced concrete slab–column connections can be increased through the use of headed shear studs. To reduce interference with slab flexural reinforcement, stud rails are often placed in an orthogonal layout. In this layout, no stud rail is placed in regions extending from the corners of a column, as opposed to stud placement in a radial layout. Some experiments have found the absence of radial stud rails could lead to premature shear failure at slab–column connections. This problem may not have been noticeable in experiments that tested slabs with either short-spans or with a high flexural reinforcement ratio. This paper presents an experimental study to evaluate the effectiveness of these stud layouts in slab–column connections whose slabs have relatively low flexural reinforcement ratios. Three full-scale slab–column connections that represent a flat plate structure with 25ft (7620mm) spans were tested. All three specimens had an identical flexural design, in which the reinforcement ratio was 0.8%. One specimen was built without shear reinforcement, and the remaining two specimens were reinforced with shear studs in either a radial or orthogonal layout. For the specimens with shear studs, calculated shear strengths were higher than their estimated flexural strengths.

Experimental and analytical studies of curved steel–concrete–steel sandwich panels under patch loads

The paper proposes a novel curved steel–concrete–steel (SCS) sandwich panel for Arctic offshore platform to resist the ice loads due to ice floes in Arctic region. The SCS sandwich panel consists of two curved steel plates infilled with a type of novel ultra-lightweight cement composite (ULCC) with a compressive strength of 60MPa and a density less than 1400kg/m3. Headed shear studs working in pairs with overlapped lengths are used to achieve composite action between the core material and steel face plates. This paper investigates the performance of curved SCS sandwich composite panel experimentally and analytically. Ten quasi-static tests on the curved sandwich composite panels subjected to patch loads are carried out to explore their failure modes, ultimate strength and load–defection behaviour. The main failure modes of the tests are identified as flexural failure, diagonal concrete strut crushing and shear tension failure. Based on the failure mechanism, a unified deep beam model is constructed to estimate the shear resistance of flat and curved SCS sandwich panels by considering equilibrium status, material yielding criteria and boundary conditions. The validations show that the modified model can provide close and conservative estimations on shear resistance for SCS sandwich composite panel.

Numerical and parametric study of curved steel-concrete-steel sandwich composite beams under concentrated loading

The curved steel-concrete-steel (SCS) sandwich structure has been developed as the ice-resistant wall for Arctic oil and gas drilling platform. This developed curved SCS sandwich structure adopts ultra-lightweight cement composite and overlapped headed shear studs as the core material and bonding measures at the steel-concrete interface, respectively. This paper develops a three-dimensional finite element (FE) model by general commercial FE program ABAQUS to simulate the ultimate strength behaviour of the curved SCS sandwich beam. The developed FE model considers the geometric and material nonlinearities of the concrete, steel plates and connectors. The reasonable agreement between FE analysis and the quasi-static tests on nine SCS sandwich beams confirms the accuracy of the FEM in predicting the ultimate shear resistance and cracks in the concrete core of the curved SCS sandwich beam. Based on this validated FE model, a subsequence parametric study comprising 54 cases investigates the influences of the curvature, thickness of the steel face plate and core material, and horizontal movements of the supports on the shear resistance of the curved SCS sandwich beams. Finally, the paper validates accuracy of an analytical model on the shear resistance of the curved SCS sandwich beam via a comparison against a total of 41 results (32 FEA and 9 tests).

COMPOSITE CONSTRUCTION OF COLD-FORMED STEEL (CFS) SECTION WITH HIGH STRENGTH BOLTED SHEAR CONNECTOR

Composite construction is well known to be effectively used in the construction of buildings and bridges using hot rolled steel (HRS) and headed studs connectors. The shear connectors provides the enhancement as established in current design codes. In this paper, the shear connection mechanism was proposed using high strength bolted shear connector to provide composite action between concrete and the steel section. The conventional headed stud shear connector was eliminated since Cold-formed steel (CFS) was used and welding was not practically possible due to thinness nature of the CFS section. Therefore, in this study investigation was carried out on the strength capacity, ductility and the ultimate flexural capacity of the proposed high strength bolted shear connector and the composite beam specimens respectively. Four push-out and two full-scale composite beam specimens were fabricated using high strength M16 bolted shear connector of Grade 8.8 connected to the top flanges of the CFS I-section and tested to failure using push-out and four-point bending tests respectively. The results show that ultimate load and ultimate moment capacities of the proposed system were significantly improved by using the proposed connectors. The experimental results were compared with theoretical results based on the provision of Eurocode 4, and good agreement between the results was observed. In conclusion, compared results proved that the ultimate moment capacity of the proposed composite beams can be estimated efficiently by using the constitutive laws as prescribed by Eurocodes and British standards.

Shear force of headed shear studs, high-strength shear studs and steel plate embedded in concrete: an experimental study

Diverse shear studs and steel plate are frequently installed within engineering structures to increase resistance of external shear force at steel frame and reinforced concrete joints. In the current study, tests were undertaken in order to compare both variable shear stud strength (normal-strength shear studs and high-strength shear studs) and type (normal shear studs and headed shear studs) with steel plate. Results have been evaluated in the context of experimental data, finite element analyses results and the current ACI318-11 code.

Finite element modelling of steel–concrete composite beams with high-strength friction-grip bolt shear connectors

High-strength friction-grip bolts (HSFGBs), that can be easily unbolted during deconstruction and structural modification, are proposed as shear connectors between the steel beam and concrete slab of composite beams in lieu of conventional headed shear studs for which deconstruction is problematic. These beams are potential sustainable and recyclable element for modern construction, but research contributions on composite beams with HSFGB shear connectors are very limited. This paper develops a three-dimensional finite element model to investigate the structural behaviour of steel–concrete composite beams with HSFGB shear connectors. Material non-linearities and the interaction of structural components are included in the model. Quasi-static finite element analysis using the dynamic explicit procedure is adopted for the analysis. The accuracy and reliability of the proposed finite element model are validated by comparing their results with available experimental results. An example is contrived to elucidate the typical mechanical performance of the composite beam, which the finite element study shows is different to that normally encountered in composite beams with headed stud connectors. Parametric studies are presented to quantify the effects of the change in the bolt spacing, diameter of hole, bolt pretension and the longitudinal reinforcement on the behaviour of the beam, so that usable design rules may be crafted.

Nonlinear finite element modelling and parametric study of curved steel–concrete–steel double skin composite panels infilled with ultra-lightweight cement composite

Curved steel–concrete–steel (SCS) double skin composite structure with shear connectors has been developed and exhibits versatile potential applications in building and offshore constructions. A novel ultra-lightweight cement composite is used as core material and headed shear studs are welded on steel face plate to achieve the composite action. This paper demonstrates a comprehensive 3D nonlinear finite element (FE) analysis of curved double skin composite panels infilled with ultra-lightweight cement composite (ULCC) under patch load. Nonlinear FE analyses are performed using ABAQUS to study the load deflection behaviour up to the maximum load resistance. A constitutive model for ultra-lightweight cement composite is generated from standard test data and assigned to the concrete materials. A simplified connector element incorporated tension–elongation behaviour is proposed for the shear studs in the curved double skin composite panels. The accuracy of the FE model is validated using experimental results from the literature in terms of load displacement curves, failure modes and maximum load resistance. An extensive parametric study is carried out to identify the effect of the rise-to-span ratio, span-to-thickness ratio, concrete compressive strength and steel yield strength and loading type on the ultimate resistance.

STRENGTH AND BEHAVIOR OF COMPOSITE STEEL TUBE CONCRETE BEAM

This paper deals with an experimental and analytical study to investigate the structural behavior of simply supported composite steel-concrete tube beams with external load, in which a concrete is connected together with steel circular tube by means of headed stud shear connectors. This type of structure not only inherits the characteristics of traditional concrete tube beams but also possesses its own unique attributes, such as advantageous mechanical performances, facilitating construction process, and low maintenance cost etc. Seven composite steel-concrete tube beams were tested to their ultimate strength. The effect of thickness and diameter of steel tube on structural performance of composite beams were investigated. Experimental results proved that, due to increase tube thickness from (2mm to 6mm), the strength increased by (63.5%) and the ultimate deflection increased by (75%). While the strength increased by (190.3%) and the ultimate deflection decreased by (47%) when the tube diameter increased from (75mm to 200mm). Based on the experimental results, a theoretical model for predicating the flexural resistance of composite steel- concrete tube beam is proposed. ANSYS computer program (version 13.0) has been used. The calculated flexural resistance based on proposed model has a high level of accuracy when compared with test results.

Behaviour and Design of Composite Beams with Stiffened and Unstiffened Web Openings

This paper presents an investigation on behaviour and design of composite beams with stiffened and unstiffened web openings. The composite beams were simply supported and had profiled steel sheeting oriented transversely to the steel beams. Nonlinear 3-D finite element models were developed to analyse the inelastic behaviour of composite beam components comprising the steel beam, concrete slab, profiled steel sheeting, headed stud shear connectors, reinforcement bars as well as interfaces among these components. In addition, the load-slip characteristic of the headed stud shear connectors in composite slabs with profiled steel sheeting were carefully incorporated into the finite element models. The finite element models of the composite beams have been validated against published experimental results. The composite beams had different moment-to-shear (M/V) ratios at the openings, stiffened and unstiffened web opening sizes, web opening locations, profiled steel sheeting, shear connections, beam lengths, concrete slab strengths and steel beam strengths. The ultimate loads of the composite beams, load-deflection relationships and modes of failure of the beams were predicted from the finite element analysis and compared well against the test results. Furthermore, the variables that influence the composite beam behaviour and ultimate load comprising different stiffened and unstiffened web opening sizes, M/V ratios at openings, web opening locations, beam lengths, concrete strengths and steel beam strengths, were also investigated in an extensive parametric study. It is shown that the ultimate loads of composite beams with stiffened web openings with horizontal stiffeners located above and below the openings, having an opening height equal to 0.6 the steel beam depth, can be considerably increased compared with that of unstiffened openings. It is also shown that the increase in structural steel strength has a remarkable effect on the composite beam ultimate loads. In addition, the ultimate loads of the composite beams with stiffened and unstiffened web openings predicted from the finite element analysis were compared with the design ultimate loads calculated using the Eurocode 4 and technical report SCI P355 published by the Steel Construction Institute for composite beams with profiled steel sheeting and rectangular stiffened and unstiffened web openings. Generally, it is shown that the design ultimate loads accurately predicted the ultimate loads of the composite beams within an average of 6% difference from the ultimate loads predicted using the finite element analysis.

Ultimate strength behavior of steel-concrete-steel sandwich beams with ultra-lightweight cement composite, Part 2: Finite element analysis

Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of 1,450 kg/m3 has been developed and used in the steel-concrete-steel (SCS) sandwich structures. This paper investigates the structural performances of SCS sandwich composite beams with ULCC as filled material. Overlapped headed shear studs were used to provide shear and tensile bond between the face plate and the lightweight core. Three-dimensional nonlinear finite element (FE) model was developed for the ultimate strength analysis of such SCS sandwich composite beams. The accuracy of the FE analysis was established by comparing the predicted results with the quasi-static tests on the SCS sandwich beams. The FE model was also applied to the nonlinear analysis on curved SCS sandwich beam and shells and the SCS sandwich beams with J-hook connectors and different concrete core including ULCC, lightweight concrete (LWC) and normal weight concrete (NWC). Validations were also carried out to check the accuracy of the FE analysis on the SCS sandwich beams with J-hook connectors and curved SCS sandwich structure. Finally, recommended FE analysis procedures were given.

Headed stud shear connector for thin ultrahigh-performance concrete bridge deck

Ultrahigh-performance concrete (UHPC) provides much higher compressive and tensile strength than conventional concrete. UHPC is advantageous for use as a bridge slab deck owing to its higher strength, stiffness, and durability. One drawback, however, is the fact that the joint region connecting the deck and girder generally has a thicker cross-section to ensure proper shear connection, which hinders making the overall UHPC deck thinner and lighter. In addition, the shear strength of stud shear connectors embedded in UHPC slab has not been verified to be the same as that in a conventional concrete deck. This study investigates a stud shear connector embedded in a UHPC deck through 15 push-out tests. The ultimate strength of the stud and relative slips are measured. The test parameters were chosen to prove the feasibility of a thinner slab. The stud aspect ratio, overall height-to-diameter, and cover thickness on top of the stud head requirement are also examined to verify the existing geometrical constraints specified in the AASHTO LRFD and Eurocode-4 design codes for UHPC decks. It was shown that the aspect ratio can be reduced from 4 to 3.1 without loss of shear strength of the stud, and the cover could be reduced from 50mm to 25mm without causing a splitting crack at the UHPC slab. However, the required ductility demand, 6mm, was not realized in all cases. Therefore, the stud shear connectors in a UHPC deck should be designed according to the elastic criterion.

Static behaviour of multi-row stud shear connectors in high- strength concrete

In regions of high shear forces in composite bridges, headed stud shear connectors need to be arranged with a small spacing in order to satisfy the design requirement of resisting the high interface shear force present at this location. Despite this, studies related to groups of headed studs are somewhat rare. This paper presents an investigation of the static behaviour of grouped stud shear connectors in high-strength concrete. Descriptions are given of five push-out test specimens with different arrangements of the studs that were fabricated and tested, and the failure modes, load-slip response, ultimate load capacities and related slip values that were obtained are reported. It is found that the load-slip equation given by some researchers based on a single stud shear connector in normal strength concrete do not apply to grouped stud shear connectors in high-strength concrete, and an algebraic load-slip expression is proposed based on the test results. Comparisons between the test results and the formulae provided by some national codes show that the equations for the ultimate capacity provided in these codes are conservative when used for connectors in high-strength concrete. A reduction coefficient is proposed to take into account the effect of the studs being in a group.

Ultimate strength behavior of steel-concrete-steel sandwich beams with ultra-lightweight cement composite, Part 1: Experimental and analytical study

Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of <TEX>$1450kg/m^3$</TEX> has been developed and used in the steel-concrete-steel (SCS) sandwich structures. ULCC was adopted as the core material in the SCS sandwich composite beams to reduce the overall structural weight. Headed shear studs working in pairs with overlapped lengths were used to achieve composite action between the core material and steel face plates. Nine quasi-static tests on this type of SCS sandwich composite beams were carried out to evaluate their ultimate strength performances. Different parameters influencing the ultimate strength of the SCS sandwich composite beams were studied and discussed. Design equations were developed to predict the ultimate resistance of the cross section due to pure bending, pure shear and combined action between shear and moment. Effective stiffness of the sandwich composite beam section is also derived to predict the elastic deflection under service load. Finally, the design equations were validated by the test results.

Sustainable and Deconstructable Semi-Rigid Flush End Plate Composite Joints

Composite construction is a popular and effective method of construction, exploiting the strengths of both reinforced concrete and structural steel in building construction in a complementary fashion. Within paradigms related to minimisation of emissions and maximisation of product recycling, these composite systems are problematic on a number of fronts. Firstly, common and traditional composite systems utilise ordinary Portland cement, which is known to be a very large contributor to atmospheric CO2 emissions. Secondly, for typical construction practices for steel-concrete composite systems, casting of the concrete onto profiled steel decking and conventional reinforcement placing are undertaken on-site, which is time consuming and labour intensive, and which can increase the cost of construction. Thirdly, composite action between the steel beam and the concrete slab is usually achieved by using headed shear studs. The headed shear studs connect these two elements permanently, which leads to much waste at the end of the service life of the building when it is demolished. This paper models a sustainable semi-rigid beam-to-column composite blind bolted connection with deconstructable bolted shear connectors using ABAQUS finite element (FE) software. In this “green” system, precast geopolymer concrete (GPC) slabs are attached compositely to the steel beam via pretensioned bolted shear connectors and the composite beam is connected to GPC-filled square columns using blind bolts. Non-linear material properties and non-linear geometric effects are considered in the simulation of a connection in hogging bending. Based on the FE modelling, using pretensioned bolts as shear connectors with GPC can improve the behaviour of semi-rigid flush end plate composite joints in terms of ductility and load capacity. Moreover, the behaviour of the bolted shear connectors should be considered in composite joint design as being very different to headed stud connectors.

Punching resistance of internal slab-column connections with double-headed shear studs

Punching shear is a brittle failure mode that may occur in slab-column connections, which may be prevented by using shear reinforcement in the slab-column connection. This paper presents comparisons between experimental results of 36 tests in internal slab-column connections with double- headed shear studs, which are largely used in North America, Europe and Asia, with theoretical results using recommendations presented by ACI 318, NBR6118, Eurocode 2 and also the Critical Shear Crack Theory (CSCT).Considering the database used it is possible to observe that ACI 318 presents conservative trends, whereas NBR 6118 showed a low coefficient of variation, but with a large number of unsafe results. Both Eurocode 2 and CSCT showed satisfactory results with Eurocode 2 presenting slightly higher performance.

Numerical Simulation on Failure Process of Rubber-Sleeved Headed Stud Shear Connector

Rubber-sleeved headed stud shear connector is flexible shear connector used in steel-concrete composite structures. In this work, nonlinear finite element model has been developed to simulate the failure process of the shear connector under shear loading. The stress distribution, deformation, crack propagation and failure mode were analyzed. The material nonlinearities of rubber, headed stud, concrete were considered in the material model. The rubber was assumed as a perfect material with no defect, and a modified reduced polynomial form of strain energy including an energy limiter and a new constant was introduced into the user material subroutine VUANISOHYPER-INV of ABAQUS software. Damaged plasticity model was used to model the concrete material. A tri-linear elastic-plastic curve was used in stud material model. Comparing the results obtained from the finite element analysis with those from push-out test, good agreement is highlighted in the capacity, ductility and failure mode of rubber-sleeved headed stud shear connector.