Research on Whole‑Process Tensile Behavior of Headed Studs in Steel–Concrete Composite Structures

Liang?Dong Zhuang,Hong?Bing Chen,Yuan Ma,Ran Ding 한국콘크리트학회 2021 International Journal of Concrete Structures and M Vol.15 No.4

The headed studs have been widely applied in steel–concrete composite structures as shear connectors. However, the tensile performance of headed studs is also key to the structural performance in many cases such as the semi-rigid composite joints including steel beam–concrete wall joint and steel column–base joint. Therefore, this study presents experimental and analytical study on the whole-process tensile behavior of headed studs. Tests on a total of 33 pullout specimens are first conducted. The tensile capacity and load–deformation behavior of the anchorage concrete, which dominates the structural performance of headed studs, are thoroughly analyzed. In addition, test data in the literature are collected for quantitatively evaluating the influence of embedment depth, bearing area, boundary conditions, and concrete strength on the tensile behavior of the anchorage concrete. On the basis of the influence evaluation, an analytical model represented by a piecewise function is proposed to describe the whole-process load–deformation behavior of the anchorage concrete and validated through the comparison between the predicted curves and all collected experimental results. Then the proposed model is applied to simulate the rotational behavior of the typical semi-rigid joint anchored by headed studs, which takes the contribution of the anchorage concrete into consideration, and is verified by experimental results. The research findings indicate that tensile behavior of anchorage concrete is crucial to the structural performance of semi-rigid joints, even for headed studs with large embedment depth and bearing area.

Application of Machine Learning in Prediction of Shear Capacity of Headed Steel Studs in Steel–Concrete Composite Structures

Cigdem Avci-Karatas 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.2

Headed studs are generally utilized as shear connectors at the interface between steel and concrete in composite structures primarily to transfer longitudinal shear force. This paper presents regression methodologies to predict the shear capacity of headed steel studs by using the concepts of minimax probability machine regression (MPMR) and extreme machine learning (EML). MPMR is carried out based on a minimax probability machine classifi cation. EML is an updated version of a single hidden layer feedforward network. From the experimental data presented in extensive literature, key input parameters infl uencing the shear capacity have been identifi ed and consolidated. The identifi ed parameters include (i) steel stud shank diameter, (ii) compressive strength of concrete, and (iii) tensile strength of headed steel stud. After careful examination of the data and their limits, about 70–75% of the mixed dataset comprising the range of the values has been used for developing MPMR and EML-based models. The input data has been normalized based on the limits of individual parameters. The remaining data has been utilized for verifi cation of the developed models. It is observed that the predicted shear strength capacity is comparable with the experimental observations. Further, the effi cacy of the models has been evaluated through several statistical parameters, namely; root mean square error, mean absolute error, the coeffi cient of effi ciency, root mean square error to observation’s standard deviation ratio, normalized mean bias error, performance index, and variance account factor. It is found that the R2 value is 0.9913 and 0.9479, respectively, for the models developed based on the concepts of MPMR and EML, indicating that the predicted value is closer to the experimental data.

Modelling headed stud shear connectors of steel-concrete pushout tests with PCHCS and concrete topping

Lucas Mognon Santiago Prates,Felipe Piana Vendramell Ferreira,Alexandre Rossi,Carlos Humberto Martins 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.4

The use of precast hollow-core slabs (PCHCS) in civil construction has been increasing due to the speed of execution and reduction in the weight of flooring systems. However, in the literature there are no studies that present a finite element model (FEM) to predict the load-slip relationship behavior of pushout tests, considering headed stud shear connector and PCHCS placed at the upper flange of the downstand steel profile. Thus, the present paper aims to develop a FEM, which is based on tests to fill this gap. For this task, geometrical non-linear analyses are carried out in the ABAQUS software. The FEM is calibrated by sensitivity analyses, considering different types of analysis, the friction coefficient at the steel-concrete interface, as well as the constitutive model of the headed stud shear connector. Subsequently, a parametric study is performed to assess the influence of the number of connector lines, type of filling and height of the PCHCS. The results are compared with analytical models that predict the headed stud resistance. In total, 158 finite element models are processed. It was concluded that the dynamic implicit analysis (quasi-static) showed better convergence of the equilibrium trajectory when compared to the static analysis, such as arc-length method. The friction coefficient value of 0.5 was indicated to predict the load-slip relationship behavior of all models investigated. The headed stud shear connector rupture was verified for the constitutive model capable of representing the fracture in the stress-strain relationship. Regarding the number of connector lines, there was an average increase of 108% in the resistance of the structure for models with two lines of connectors compared to the use of only one. The type of filling of the hollow core slab that presented the best results was the partial filling. Finally, the greater the height of the PCHCS, the greater the resistance of the headed stud.

Experimental and numerical study on static behavior of grouped large-headed studs embedded in UHPC

Yuqing Hu,Guotang Zhao,Zhiqi He,Jianan Qi,Jingquan Wang 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.36 No.1

The static behavior of grouped large-headed studs (d = 30 mm) embedded in ultra-high performance concrete (UHPC) was investigated by conducting push-out tests and numerical analysis. In the push-out test, no splitting cracks were found in the UHPC slab, and the shank failure control the shear capacity, indicating the large-headed stud matches well with the mechanical properties of UHPC. Besides, it is found that the shear resistance of the stud embedded in UHPC is 11.4% higher than that embedded in normal strength concrete, indicating that the shear resistance was improved. Regarding the numerical analysis, the parametric study was conducted to investigate the influence of the concrete strength, aspect ratio of stud, stud diameter, and the spacing of stud in the direction of shear force on the shear performance of the large-headed stud. It is found that the stud diameter and stud spacing have an obvious influence on the shear resistance. Based on the test and numerical analysis results, a formula was established to predict the load-slip relationship. The comparison indicates that the predicted results agree well with the test results. To accurately predict the shear resistance of the stud embedded in UHPC, a design equation for shear strength is proposed. The ratio of the calculation results to the test results is 0.99.

Compressive performance with variation of yield strength and width-thickness ratio for steel plate-concrete wall structures

최병정,강철규,김원기,김우범 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.5

The primary objectives of this paper are to describe the buckling patterns and to determine the squash load of steel plate-concrete (SC) walls. The major variables in this study were the width-thickness (B/t) ratio and yield strength of surface steel plates. Six SC walls were tested, and the results include the maximum strength, buckling pattern of steel plates, strength of headed studs, and behavior of headed studs. Based on the test results, the effects of the B/t ratio on the compressive strength are also discussed. The paper also presents recommended effective length coefficients and discusses the effects of varying the yield strength of the steel plate, and the effects of headed studs on the performance of SC structures based on the test results and analysis.

Double-head Stud로 횡구속된 RC기둥의 횡구속 모델 평가

김성수 청주대학교 산업과학연구소 2006 産業科學硏究 Vol.24 No.1

The purpose of this study is to nvestigate the confinement effect and strength increment by head and to propose the confinement model for column using the head at end of lateral tie. Also, the test results for ultimate strength and strength gain factor of columns in this study and previous study were compared with the existing analytical models. Based on the test results, the Saatcioglu's model estimates confinement effects was closed to experimental value and the developed analytical approach considered the head was capable of predicting the strength gain factor results with a resonable accuracy.

Effect of Rib Geometry in Steel–Concrete Composite Beams with Deep Profiled Sheeting

Ahmed Albarram,Jawed Qureshi,Ali Abbas 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.3

Presented are the results from a fi nite element model of steel–concrete composite beams with deep decks and a comparison with various analytical/design methods. Using a deck deeper than 80 mm are becoming popular with a desire for longer spanning capability and lower concrete volume. However, there are no design rules in either American or European design codes for using a deck deeper than 80 mm, as both codes limit the deck rib height to 75 and 85 mm, respectively for using the stud’s capacity formula. Therefore, research is needed to establish the design stud capacity in beams with decks deeper than 80 mm. After extensive validation, the 3-D FE model is used for a parametric study with tests having decks deeper than 80 mm. The parameters include rib geometries, studs’ layout and concrete slab reinforcements. The FE results showed that stud capacity with narrow and deep decks (100–150 mm) is about 70% of the conventional decking (60–80 mm deep). The stud capacities from the numerical results were compared to the predicted strengths from the design/theoretical models. While the equations from the concrete pull-out failure mode by Johnson and Yuan (Proc Inst Civ Eng Struct Build 128(3):252–263, 1998) gave reasonable predictions with a coeffi cient of variation as 11%, both EC4 and ANSI/AISC rules provided inaccurate and inconsistent predicted strengths. A generalised stud capacity formula should be developed in the design codes for decks deeper than 80 mm.

Structural Behavior of Steel–Concrete Composite Girders Composed of Demountable Shear Connectors

정대성,박세현,김태형,김철영 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.2

In recent years, many studies on demountable shear connectors have been conducted to facilitate the dismantlement and replacement of precast slabs for steel–concrete composite bridges. Welded headed studs are still mainly used for the horizontal shear synthesis of steel girders and precast concrete slabs, and are adopted in Korean design standards. Because the service life of concrete slabs is much shorter than that of steel girders, however, easy replacement of damaged or old slabs will improve the economic feasibility of the entire bridge during its service life. Therefore, in this study, a new concept of bolted shear connectors is proposed for easy deconstruction and reconstruction of precast concrete slabs. The structural behavior of the proposed connector was verified through horizontal shear and bending tests on composite girder specimens. The connector demonstrated sufficient synthesis performance to replace the conventional welding stud. It also satisfies the current ductility design criterion and flexural performance for slip displacement; hence, we conclude that the novel connector can be used under the existing design standards.

Shear and tensile behaviors of headed stud connectors in double skin composite shear wall

Jia-Bao Yan,Zhe Wang,Tao Wang,Xiao-Ting Wang 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.6

This paper studies shear and tensile behaviors of headed stud connectors in double skin composite (DSC) structure. Firstly, 11 push-out tests and 11 tensile tests were performed to investigate the ultimate shear and tensile behaviors of headed stud in DSC shear wall, respectively. The main parameters investigated in this test program were height and layout of headed stud connectors. The test results reported the representative failure modes of headed studs in DSC structures subjected to shear and tension. The shear-slip and tension-elongation behaviors of headed studs in DSC structures were also reported. Influences of different parameters on these shear-slip and tension-elongation behaviors of headed studs were discussed and analyzed. Analytical models were also developed to predict the ultimate shear and tensile resistances of headed stud connectors in DSC shear walls. The developed analytical model incorporated the influence of the dense layout of headed studs in DSC shear walls. The validations of analytical predictions against 22 test results confirmed the accuracy of developed analytical models.

Experimental studies of headed stud shear connectors in UHPC Steel composite slabs

Xiao-long Gao,Jun-Yan Wang,Jia-Bao Yan 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.5

Due to the high compressive and tensile strength of ultra-high performance concrete (UHPC), UHPC used in steel concrete composite structures provided thinner concrete layer compared to ordinary concrete. This leaded to the headed stud shear connectors embedded in UHPC had a low aspect ratio. In order to systematic investigate the effect of headed stud with low aspect ratio on the structural behaviors of steel UHPC composite structure s this paper firstly carried out a test program consisted of twelve push out specimens. The effects of stud height, aspect ratio and reinforcement bars in UHPC on the structural behaviors of headed studs were investigated. The push out test results shows that the increasing of stud height did not obviously influence the structural behaviors of headed studs and the aspect ratio of 2.16 was proved enough to take full advantage of the headed stud strength. Based on the test results, the equation considering the contribution of weld collar was modified to predict the shear strength of headed stud embedded in UHPC. The modified equation could accurately predict the shear strength of headed stud by comparing with the experimental results. On the basis of push out test results, bending tests consisted of three steel UHPC composite slabs were conducted to investigate the effect of shear connection degree on the structural behaviors of composite slabs. The bending test results revealed that the shear connection degree had a significantly influence on the failure modes and ultimate resistance of composite slabs and composite slab with connection degree of 96% in s hear span exhibited a ductile failure accompanied by the tensile yield of steel plate and crushing of UHPC. Finally, analytical model based on the failure mode of composite slabs was proposed to predict the ultimate resistance of steel UHPC composite slabs with different shear connection degrees at the interface.