Behavior Of Stud Shear Connectors Research Articles

Stud-concrete interactional model of shear connectors in steel-concrete composite structures

A theoretical calculation method, named stud-concrete interactional model, of load-slip relationship of stud shear connectors in composite structures is presented. This model has been developed based on the elastic foundation beam theory and considers the different stress states of the concrete around studs during the damage process. Two important stud-concrete interaction parameters, called equivalent spring stiffness and yielding slip, are introduced for the first time to quantify the shear contribution of concrete and the relative slip between stud and concrete, respectively. The range of yielding slip has been determined based on a force-flow model and a finite element model. The proposed stud-concrete interactional model has been utilized to derive the load-slip formula considering the elastic, elastoplastic, and plastic stages of stud shear connectors. Experimental results show that the proposed formula are valid and outperform existing formulas. This paper offers new insight into the shear behavior of stud shear connectors.

Research on Static Behavior of Stud Shear Connectors after Strong-corrosion Based on Push-out Test

To study the shear bearing performance and failure mechanism of stud shear connectors after strong-corrosion, six groups of stud shear connectors were designed and then welded to the specimen. They are corroded by hydrochloric acid time for 0 h, 2 h, 12 h, 24 h, 48 h, and 72 h. Herein, the loading process, load-slip curve, shear bearing capacity, and failure mode were obtained by the push-out test. The bearing capacity formula was also proposed by the stress mechanism of 84 finite element models. The results of the study on stud shear connectors show that the shear capacity, deformation capacity and slip decrease gradually with the extension of corrosion time. Among them, the enlargement in the diameter exerts considerable influence on their shear capacity. Notwithstanding, the shear bearing capacity slightly increases with stud shear connectors lengthened. The concrete strength grade can strengthen the shear capacity. Finally, the shear bearing capacity formula, taking the reliability coefficient into account, is proposed by the exit test data of 104 stud shear connectors.

Behavior of Stud Shear Connectors with Increasing Concrete Strength

Behavior of Stud Shear Connectors with Increasing 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.

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.

Experimental Study on Impact Behavior of Stud Shear Connectors between Concrete Slab and Steel Beam

AbstractThis paper deals with the shear behavior of steel stud connectors between a concrete slab and steel beam under static and impact loading. An experimental program involving four static and n...

Behaviour of Corroded Single Stud Shear Connectors.

In this study, the effect of corrosion on the static behavior of stud shear connectors was investigated. An innovative test setup for single stud shear connectors was designed and established. Two series of specimens having different stud diameters were fabricated and tested. The test specimens were firstly corroded to different corrosion rates by the electronic accelerating method. Static loading tests were then performed to obtain the load-slip curves and ultimate strengths of the corroded test specimens. The actual corrosion rates were measured from the studs obtained from the tested specimens. The test results were compared with the push out test specimens having similar corrosion rates. It is shown that the test results obtained from the single stud shear connectors are conservative compared with the corroded push test specimens, which prove the validation of the single stud shear connector test method. The effect of corrosion on the behavior of stud shear connectors was also presented.

Mechanical behavior of stud shear connectors embedded in HFRC

Hybrid-fiber reinforced concrete (HFRC) may provide much higher tensile and flexural strengths, tensile ductility, and flexural toughness than normal concrete (NC). HFRC slab has outstanding advantages for use as a composite bridge potential deck slab owing to higher tensile strength, ductility and crack resistance. However, there is little information on shear connector associated with HFRC slabs. To investigate the mechanical behavior of the stud shear connectors embedded in HFRC slab, 14 push-out tests (five batches) in HFRC and NC were conducted. It was found that the stud shear connector embedded in HFRC had a better ductility, higher stiffness and a slightly larger shear bearing capacity than those in NC. The experimentally obtained ultimate resistances of the stud shear connectors were also compared against the equations provided by GB50017 2003, ACI 318-112011, AISC 2011, AASHTO LRFD 2010, PCI 2004, and EN 1994-1-1 (2004), and an empirical equation to predict the ultimate shear connector resistance considering the effect of the HFRC slabs was proposed and validated by the experimental data. Curve fitting was performed to find fitting parameters for all tested specimens and idealized load-slip models were obtained for the specimens with HFRC slabs.

Fatigue behavior of stud shear connectors in steel and recycled tyre rubber-filled concrete composite beams

This paper extends our recent work on the fatigue behavior of stud shear connectors in steel and recycled tyre rubber-filled concrete (RRFC) composite beams. A series of 16 fatigue push-out tests were conducted using a hydraulic servo testing machine. Three different recycled tyre rubber contents of concrete, 0%, 5% and 10%, were adopted as main variable parameters. Stress amplitudes and the diameters of studs were also taken into consideration in the tests. The results show that the fatigue lives of studs in 5% and 10% RRFC were 1.6 and 2.0 times greater of those in normal concrete, respectively. At the same time, the ultimate residual slips' values of stud increased in RRFC to highlight its better ductility. The average ultimate residual slip value of the studs was found to be equal to a quarter of studs' diameter. It had also been proved that stress amplitude was inversely proportional to the fatigue life of studs. Moreover, the fatigue lives of studs with large diameter were slightly shorter than those of smaller ones and using larger ones had the risk of tearing off the base metal. Finally, the comparison between test results and three national codes was discussed.

Experimental Investigation of Corroded Stud Shear Connectors Subjected to Fatigue Loading

AbstractAn experimental investigation on corroded composite push-out specimens was performed to investigate the behavior of stud shear connectors subjected to fatigue loading. A total of 14 standard push-out specimens were tested under static and fatigue loading. A static push-out test was performed to obtain the ultimate strengths for reference. The expected corrosion rate of test specimens ranged from 0 to 50%. The main purpose of these tests was to determine the fatigue life and the reduction effect of the fatigue life caused by the corrosion. The effect of corrosion on the fatigue crack, load-slip curves, and failure modes were also studied. The test results were also compared with current Eurocode design predictions, which are only for a specimen without corrosion. The suitability of the Eurocode design equation for fatigue life of corroded composite push-out specimens was evaluated.

Experimental investigation and design of corroded stud shear connectors

In this study, the effect of corrosion on the static behavior of stud shear connectors was investigated. Two series of push test specimens having different stud diameters were fabricated according to Eurocode 4. The test specimens were first corroded to different corrosion rates by electronic accelerating method. Static loading tests were then performed to obtain the load-slip curves and ultimate strengths of corroded test specimens. Material properties of the concrete and steel studs used in the test specimens were also measured. Actual corrosion rates were measured from the studs obtained from the tested specimens. Design methods specified in current design standards are used to predict the design strengths of test specimens. It is shown that the design strengths are unconservative for corroded test specimens. Therefore, a new design equation is proposed which enables the designer to consider the effect of corrosion.

Closure to “Strength Analysis of Steel-Concrete Composite Beams in Combined Bending and Shear” by Qing Quan Liang, Brian Uy, Mark A. Bradford, and Hamid R. Ronagh

The strength analysis of steel-concrete composite beams in combined bending and shear is evaluated. The cross-sectional area of the beam element was modified to make it equivalent in both strength and stiffness to the actual stud shear connectors in the composite beam. The 3D beam elements were used in the finite-element model to simulate the discrete behavior of stud shear connectors in composite beams. It was observed that the stiffness of the shear connection modeled using finite elements was almost the same as the stiffness of the shear connection in the real beam. The ultimate strain of 0.25 was assured for structural steel in the analysis and the experimental values of the yield strength and ultimate strength were used in the analysis for the steel. The model can be used to determine the ultimate strengths of supported composite beams under combined bending and shear.

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

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

Shear Strength of Stud Connectors in Lightweight and Normal-Weight Concrete

Steel-concrete composite construction using normal weight concrete has been used since early in the 1920s. Substantial use of composite construction began mainly for bridge structures in the 1950s as a result of the work done by Viest. Its primary growth in building construction during the last decade was a result of the simplified design provisions introduced into the 1961 AISC Specification. The development of these provisions were based on studies reported by Slutter and Driscoll. This study summarizes the results of tests on 48 two-slab pushout specimens. The main purpose of the investigation was to evaluate the capacity and behavior of stud shear connectors embedded in lightweight concrete. Two different types of normal-weight aggregates and three types of lightweight aggregate were examined. The lightweight concretes were made with both lightweight coarse aggregate with natural sand and with lightweight fines.