• Steel and Composite Structures
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• v.39 no.4
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• pp.419-433
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• 2021

In composite structures, shear connectors are crucial components to resist the relative slip between the steel and concrete, and thereby to achieve the composite actions. In the service stage, composite structures are usually in elastic state, so the elastic stiffness of the shear connection is a quite important parameter in the structural analysis of composite structures. Nevertheless, the existing studies mainly focus on the load-slip relationship rather than the tangent stiffness at the initial elastic stage. Furthermore, when composite beams subjected to torque or local load, shear connections are affected by both tensile force and shear force. However, the stiffness of shear connections under combined effects appears not to have been discussed hitherto. This paper investigates the initial elastic stiffness of stud connections under combined effects of biaxial forces. The initial expression and the relevant parameters are obtained by establishing a simplified analytical model of the stud connection. Afterwards, parametric finite element analysis is performed to investigate the effects of the relevant factors, including the stud length, stud diameter, elastic modulus of concrete, elastic modulus of steel and volume ratio of reinforcement. The feasibility of the proposed modelling has been proved by comparing with sufficient experimental tests. Based on the analytical analysis and the extensive numerical simulations, design equations for predicting the initial elastic stiffness of stud connections are proposed. The comparison between the equations and the data of finite element models demonstrates that the equations are accurate enough to serve for engineering communities.

• Steel and Composite Structures
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• v.48 no.2
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• pp.131-143
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• 2023

The CFRP bar was used to achieve more ductile and durable headed-stud shear connectors in composite components. Three series of push-out tests were firstly conducted, including specimens reinforced with pure steel fibers, steel and CFRP bars. The distributed stress was measured by the commercial PPP-BOTDA (Pre-Pump-Pulse Brillouin optical time domain analysis) optical fiber sensor with high spatial resolution. A series of numerical analyses using non-linear FE models were also made to study the shear force transfer mechanism and crack response based on the test results. Test results show that the CFRP bar increases the shear strength and stiffness of the large diameter headed-stud shear connection, and it has equivalent reinforcing effects on the stud shear capacity as the commonly used steel bar. The embedded CFRP bar can also largely improve the shear force transfer mechanism and decrease the tensile stress in the transverse direction. The parametric study shows that low content steel fibers could delay the crack initiation of slab around the large diameter stud, and the CFRP bar with normal elastic modulus and the standard reinforcement ratio has good resistance to splitting crack growth in headed stud shear connectors.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.10a
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• pp.181-185
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• 1993

A useful finite element method to determine the stiffness of assembled member by stud bolt was introduced in this paper. Since threads on clamped members and stud bolts may produce different stress distribution, brief theories and equations based on bolt and nut may produce less conservative results or, this case. A finite element model using non-linear gap element was indtroduced to find out the basic feature of stress distribution caused by threads on both stud and member.

• 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.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.1
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• pp.18-28
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• 2022

The turbulence stimulation effect of studs for boundary layer over a flat plate was investigated through the flow measurement in KRISO cavitation tunnel. For the test, Laser Doppler Velocimetry (LDV) and three flat plate models were used: (1) flat plate without studs; (2) flat plate with one stud row; (3) flat plate with two stud rows. The dimension and location of stud rows and the inflow speed were selected considering test conditions for standard-sized model ships in KRISO towing tank. The boundary layer characteristics of test models were analyzed and compared in terms of mean velocity profiles, turbulence intensity profiles, boundary layer thickness, and shape factor. In the case of the flat plate without studs, transition from laminar to turbulent flow occurred around Re_x=3.83 ~ 5.19 × 10⁵. In the case of flat plates with stud rows, the flow rapidly changed into turbulent flow right after passing the first stud row. In the state where turbulence was already developed, the second stud row slightly increased the turbulence intensity near the top of the stud, but did not significantly affect the boundary layer characteristics such as mean velocity distribution, boundary layer thickness, and shape factor.

• The Journal of the Korean dental association
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• v.32 no.9 s.304
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• pp.620-628
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• 1994

Stud attachment는 overdenture와 overlay partial denture에 이용되며 임상술식 및 기공과정이 간편하며 가격이 저렴하여 많이 이용되고 있다. 여기에서는 Stud attachment(대한치과의사협회지 1993년 7-8월호)에 이어서 최근에 개발됐거나 우리가 임상에 응용하기에 적합하다고 생각되는 Micro-Fix, Dalbo-B, Dalbo-Rotex attachment에 관하여 설명하고자 한다.

• The Journal of the Korean dental association
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• v.32 no.8 s.303
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• pp.550-556
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• 1994

Stud attachment는 overdenture와 overlay partial denture에 이용되며 임상술식 및 기공과정이 간편하며 가격이 저렴하여 많이 이용되고 있다. 여기에서는 Stud attachment(대한치과의사협회지 1993년 7월호)에 이어서 최근에 개발됐거나 우리가 임상에 응용하기에 적합하다고 생각되는 Micro-Fix, Dalbo-B, Dalbo-Rotex attachment에 관하여 설명하고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.582-587
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• 1993

A robot application system is developed for dual purpose of stud welding and are welding to weld plates in the manufacturing of elevator cabin. The production quantity is not so big to accommodate separate stations for stud welding and are welding respectively while the need for randomization of the processes is urgent. A robot with specification for spot welding is chosen, which is appropriate for stud welding. Some implementations are made so that the robot may also be shared for are welding process. Common jig and fixture is designed for the dual purpose. Important aspects in the procedure of system design, installation, and commissioning are stated, and signal set-ups and logic diagrams are illustrated.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.7-13
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• 1998

In this paper, an automatic ball-stud inspection system has been developed using the computer-aided vision system. Index table has been used to get the rapid measurement and multi-camera has been used to get the high resolution in physical system. Camera calibration was suggested to perform the reliable inspection. Image processing and data analysis algorithms for ball stud inspection system have been investigated and were performed quickly with high accuracy. As a result, inspection system of a ball stud could be used with a high resolution in real time.

• Journal of the Korean Professional Engineers Association
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• v.19 no.3
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• pp.23-30
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• 1986

This study summarizes the results of tests on 18 two-slab push out specimens. The main purpose of tile survey was to evaluate the capacity and behavior of stud shear connectors embedded in high strength normal concrete (F$\sub$c/=260～390kg/$\textrm{cm}^2$). The normal concrete was made with crushed stones and natural sand near the Han River. Two different diameters (ø19mm, ø16 mm) of stud shear connectors were used for push out specimens. The following conclusions were drawn from this study. 1) The shear strength of stud connectors embedded in high strength concrete (F$\sub$c/=260～390kg/$\textrm{cm}^2$) was influenced by tensile stress of the stud shear connectors. The following empirical function described the test results: q$\sub$u/=0.5A$\sub$s/√F$\sub$c/E$\sub$c/$\leq$0.7A$\sub$u/F$\sub$u/ 2) The maximum load in this study was reached at slips varying from 2.5～6mm.