• Steel and Composite Structures
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• v.7 no.5
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• pp.391-404
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• 2007

This paper presents push-out tests of stud shear connectors to examine their fatigue behavior for developing a new composite bridge deck system. The fifteen push-out specimens of D16 mm stud welded on 9 mm steel plate were fabricated according to Eurocode-4, and a series of fatigue endurance test and residual strength test were performed. Additionally, the stiffness and strength variations by cyclic loading were compared. The push-out test, when the stiffness reduction ratio of the specimens was 0.95 under cyclic load, resulted in the failure of the studs. The stiffness variation of the push-out specimens additionally showed that the application of cyclic loads reduced the residual strength. The fatigue strength of the shear connectors were compared with the design values specified in the Eurocode-4, ASSHTO LRFD and JSSC codes. The comparison result showed that the fatigue endurance of the specimens satisfies the design values of these codes.

• Steel and Composite Structures
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• v.23 no.2
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• pp.239-250
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• 2017

In the concept of two-parameter fatigue failure criterion, the material fatigue failure is determined by the damage degree and the current stress level. Based on this viewpoint, a residual strength degradation model for stud shear connectors under fatigue loads is proposed in this study. First, existing residual strength degradation models and test data are summarized. Next, three series of 11 push-out specimen tests according to the standard push-out test method in Eurocode-4 are performed: the static strength test, the fatigue endurance test and the residual strength test. By introducing the "two-parameter fatigue failure criterion," a residual strength calculation model after cyclic loading is derived, considering the nonlinear fatigue damage and the current stress condition. The parameters are achieved by fitting the data from this study and some literature data. Finally, through verification using several literature reports, the results show that the model can better describe the strength degradation law of stud connectors.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.113-120
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• 2002

A shear connection in composite bridges with precast decks has considerable characteristics different from cast-in-place deck bridges such as shear pocket and bedding layer. Thus, it is necessary to build design basis of the shear connector in precast decks through the experiments. In order to estimate fatigue life of shear connector in precast deck bridges, push-out fatigue tests were conducted with parameter, bedding layer thickness. As a result of the tests, failure modes of shear connector were observed. Consequently, empirical S-N curve equations of stud shear connector in precast deck bridges were proposed in this paper.

• Steel and Composite Structures
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• v.22 no.2
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• pp.353-368
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• 2016

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.

• Steel and Composite Structures
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• v.50 no.6
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• pp.659-674
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• 2024

Casting Ultra High-Performance Concrete (UHPC) on an orthotropic steel deck and forming a composite action by connectors could improve the steel deck fatigue performance. This study presents the mechanical performance of a proposed post-combination connection between UHPC and steel, which had a low constraint effect on UHPC shrinkage. A total of 10 push-out tests were conducted for static and fatigue performance investigations. And the test results were compared with evaluation methods in codes to verify the latter's applicability. Meanwhile, nonlinear simulation and parametric works with material damage plasticity models were also conducted for the static and fatigue failure mechanism understanding. The static and fatigue test results both showed that fractures at stud roots and surrounding local UHPC crushes were the main failure appearances. Compared with normally arranged studs, group arrangement could result in reductions of static stud shear stiffness, strength, and fatigue lives, which were about 18%, 12%, and 27%, respectively. Compared with the test results, stud shear capacity and fatigue lives evaluations based on the codes of AASHTO, Eurocode 4, JSCE and JTG D64 could be applicable in general while the safety redundancies tended to be smaller or even insufficient for group studs. The analysis results showed that arranging studs in groups caused obviously uneven strain distributions. The severer stress concentration and larger strain ranges caused the static and fatigue performance degradations of group studs. The research outcome provides a very important basis for establishing a design method of connections in the novel post-combination steel-UHPC composite deck.

• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.109-121
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• 2022

Twelve push-out test specimens were conducted with various parameters to study the static and fatigue performance of a new through-bolt shear connector transferring the shear forces of interface between prefabricated hybrid fiber reinforced concrete (HFRC) slabs and steel girders. It was found that the fibers could improve the fatigue life, capacity and initial stiffness of through-bolt shear connector. While the bolt-hole clearance reduced, the initial stiffness, capacity and slippage of through-bolt shear connector increased. After the steel-concrete interface properties were improved, the initial stiffness increased, and the capacity and slippage reduced. Base on the test results, the equation of the load-slip curve and capacity of through-bolt shear connector with prefabricated HFRC slab were obtained by the regression of test results, and the allowable range of shear force under fatigue load was recommended, which could provide the reference in the design of through-bolt shear connector with prefabricated HFRC slabs.

• Steel and Composite Structures
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• v.24 no.4
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• pp.467-479
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• 2017

The stud is one of the most frequently used shear connectors which are important to the steel-concrete composite action. The static and fatigue behavior of stud in the steel fiber reinforced concrete (SFRC) were particularly concerned in this study through the push-out tests and analysis. It was for the purpose of investigating and explaining a tendency proposed by the current existing researches that the SFRC may ameliorate the shear connector's mechanical performance, and thus contributing to the corresponding design practice. There were 20 test specimens in the tests and 8 models in the analysis. According to the test and analysis results, the SFRC had an obvious effect of restraining the concrete damage and improving the stud static performance when the compressive strength of the host concrete was relatively low. As to the fatigue aspect, the steel fibers in concrete also tended to improve the stud fatigue life, and the favorable tensile performance of SFRC may be the main reason. But such effect was found to vary with the fatigue load range. Moreover, the static and fatigue test results were compared with several design codes. Particularly, the fatigue life estimation of Eurocode 4 appeared to be less conservative than that of AASHTO, and to have higher safety redundancy than that of JSCE hybrid structure guideline.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.621-628
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• 2003

Stud shear connectors are the most commonly used shear connectors: up to 22mm studs are usually used in steel-concrete composite structures. To expand the current design codes for stud connectors, large studs with a diameter of more than 25mm should be investigated. Through push-out tests on large stud shear connectors that transcend the limitation of current design codes, fatigue behavior was investigated and comparisons with design equations performed. The shear stiffness of the connectors in elastic range was evaluated through shear tests on 25mm, 27mm, and 30mm studs and compared with those from static tests. The fatigue behavior of large studs was discussed in terms of residual slip and load-slip curves. The initiation of fatigue cracks in the welding part could be detected through the history of displacement range. Test results showed that the design fatigue endurance of S-N curves in current design codes could be applied to large stud shear connector.

• Steel and Composite Structures
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• v.25 no.1
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• pp.79-92
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• 2017

Initial damage to a stud due to corrosion, fatigue, unexpected overloading, a weld defect or other factors could degrade the shear capacity of the stud. Based on typical push-out tests, a FEM model and theoretical formulations were proposed in this study. Six specimens with the same geometric dimensions were tested to investigate the effect of the damage degree and location on the static behavior and shear capacity of stud shear connectors. The test results indicated that a reduction of up to 36.6% and 62.9% of the section area of the shank could result in a dropping rate of 7.9% and 57.2%, respectively, compared to the standard specimen shear capacity. Numerical analysis was performed to simulate the push-out test and validated against test results. A parametrical study was performed to further investigate the damage degree and location on the shear capacity of studs based on the proposed numerical model. It was demonstrated that the shear capacity was not sensitive to the damage degree when the damage section was located at 0.5d, where d is the shank diameter, from the stud root, even if the stud had a significant reduction in area. Finally, a theoretical formula with a reduction factor K was proposed to consider the reduction of the shear capacity due to the presence of initial damage. Calculating K was accomplished in two ways: a linear relationship and a square relationship with the damage degree corresponding to the shear capacity dominated by the section area and the nominal diameter of the damaged stud. This coefficient was applied using Eurocode 4, AASHTO LRFD (2014) and GB50017-2003 (2003) and compared with the test results found in the literature. It was found that the proposed method produced good predictions of the shear capacity of stud shear connectors with initial damage.

• Steel and Composite Structures
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• v.2 no.1
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• pp.51-66
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• 2002

Perforated shear connectors currently used in composite steel and concrete structures are described and evaluated. Modifications of the perforated connector suitable for common use injavascript:confirm_mark('abe', '1'); civil and bridge engineering are proposed. The connectors were tested in laboratories of CTU Prague for shear load capacity. Push tests of connectors with 32 mm openings and with 60 mm openings, both in normal and lightweight concrete of different strength characteristics and with different transverse reinforcement, were carried out. The experimental study also dealt with the connector height and parallel arrangement of two connectors and their influence on shear resistance. While extensive tests with static loading were carried out, fatigue tests under repeated loading are still in progress. After statistical evaluation of the experimental results and comparisons with other available data the authors developed reasonable shear resistance formulas for all proposed arrangements.