Experimental and Analytical Investigations on the Hat Shaped Shear Connector in the Steel-Concrete Composite Flexural Member

김영호,최훈,이승식,윤순종 한국강구조학회 2011 International Journal of Steel Structures Vol.11 No.1

Over the last decade, there are many research results on the new type shear connectors to solve the problems associated with the headed stud shear connector. It was revealed that the new type shear connector has better structural safety, welding quality,constructability, cost-effectiveness, etc. Especially, perforated shear connector (perfobond shear connector) which has superior fatigue resistance and constructability is receiving attention among various types of shear connectors. In this study, we suggest the new type shear connector which improved the perfobond shear connector. Newly suggested hat shaped shear connector can be used instead of headed stud shear connector commonly used in the concrete-steel composite beam. To evaluate the load carrying capacity of this hat shaped shear connector, push-out tests are carried out and test results are analyzed. In addition,the finite element analysis is conducted on the concrete slab having shear connector to investigate the stress distribution pattern affected by the presence of hat shaped shear connector. The existing design equations for the perfobond shear connectors are reviewed briefly and the equation for the prediction of load carrying capacity of new type hat shaped shear connector is suggested based on the experimental results, finite element analysis results, and existing equations suggested in the previous studies.

Experimental behavior of double-row Y-type perfobond rib shear connectors

Kim, Sang-Hyo,Han, Oneil,Kim, Kun-Soo,Park, Jun-Seung Elsevier 2018 Journal of constructional steel research Vol.150 No.-

<P><B>Abstract</B></P> <P>Although existing studies have only analyzed Y-type perfobond rib shear connectors arranged in a single row, practical applications can apply numerous such connectors to beams with narrow spaces between them. The present study aimed to evaluate the structural behavior of double-row Y-type perfobond rib shear connectors, and thus describe grouped Y-type perfobond rib shear connectors. Push-out tests were conducted in accordance with Eurocode-4, and the relative slip, shear resistance, and ductility were measured. There were two primary variables (spacing and number of Y-type perfobond rib shear connectors) and three types of test specimens: single row, double rows (120 mm spacing), and double rows (300 mm spacing). The representative single-row specimen was used to validate the push-out test results by providing a comparison with previous tests, and provided a shear resistance reference value. The other two specimen types consisted of multiple Y-type perfobond rib shear connectors attached in parallel to an H-beam. Test results revealed that shear resistance increased as the number of shear connectors increased; however, the structural behavior depended on the shear connector spacing. The specimen with wider spacing demonstrated a better ultimate load and ductility relative to the specimen with narrower spacing. Wider shear connector spacing thus leads to better structural behavior retention.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Evaluated shear behavior of double-row Y-type perfobond shear connectors </LI> <LI> Main variables were spacing and number of shear connectors. </LI> <LI> Shear resistance increases with increase in number of shear connectors. </LI> <LI> Wider spacing led to better ultimate load and ductility. </LI> </UL> </P>

Damage assessment of shear connectors with vibration measurements and power spectral density transmissibility

Li, Jun,Hao, Hong,Xia, Yong,Zhu, Hong-Ping Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.2

Shear connectors are generally used to link the slab and girders together in slab-on-girder bridge structures. Damage of shear connectors in such structures will result in shear slippage between the slab and girders, which significantly reduces the load-carrying capacity of the bridge. Because shear connectors are buried inside the structure, routine visual inspection is not able to detect conditions of shear connectors. A few methods have been proposed in the literature to detect the condition of shear connectors based on vibration measurements. This paper proposes a different dynamic condition assessment approach to identify the damage of shear connectors in slab-on-girder bridge structures based on power spectral density transmissibility (PSDT). PSDT formulates the relationship between the auto-spectral densities of two responses in the frequency domain. It can be used to identify shear connector conditions with or without reference data of the undamaged structure (or the baseline). Measured impact force and acceleration responses from hammer tests are analyzed to obtain the frequency response functions at sensor locations by experimental modal analysis. PSDT from the slab response to the girder response is derived with the obtained frequency response functions. PSDT vectors in the undamaged and damaged states can be compared to identify the damage of shear connectors. When the baseline is not available, as in most practical cases, PSDT vectors from the measured response at a reference sensor to those of the slab and girder in the damaged state can be used to detect the damage of shear connectors. Numerical and experimental studies on a concrete slab supported by two steel girders are conducted to investigate the accuracy and efficiency of the proposed approach. Identification results demonstrate that damages of shear connectors are identified accurately and efficiently with and without the baseline. The proposed method is also used to evaluate the conditions of shear connectors in a real composite bridge with in-field testing data.

The Shear Behavior of Precast Concrete Sandwich Panels with W-shaped SGFRP Shear Connectors

Huanzhi Jiang,Zhengxing Guo,Jiabin Liu,Hui Liu 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.10

This paper presents a horizontal direct shear push-out test program to evaluate the shear behavior of Precast Concrete Sandwich Panel (PCSP) systems with W-shaped Steel Glass Fiber-reinforced Polymer (SGFRP) shear connectors. The experimental program is composed of twelve PCSPs reinforced with W-shaped SGFRP connectors and six PCSPs for comparison that were panels using pure W-shaped GFRP connectors, GFRP pin connectors and stainless-steel truss connectors. The peak shear load, the relationships of shear force-average relative slip, the shear performance of each connector, and the effects of different height, angle and diameter of the SGFRP connector were investigated in this paper. The test results indicate that all specimens with the W-shaped SGFRP shear connectors in this study exhibited an elastic-brittle response caused by pull-out of certain connectors before the ultimate strength was utilized fully and the ductility of the SGFRP material did not play out. Nevertheless, the shear capacity of panels with SGFRP connectors was approximately 2 times that with pure W-shaped GFRP connectors in the case of all parameters being the same, approximately 2 times that with stainless-steel truss connectors for which diameter was reduced by a half, and approximately 2.5 times that with GFRP pin connectors. A reasonable design of connector diameter, spacing and measure of strengthened anchorage is required to ensure the ductile failure of panels.

Investigation of pipe shear connectors using push out test

Saeed Nasrollahi,Shervin Maleki,Mahdi Shariati,Aminaton Marto,Majid Khorami 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.27 No.5

Mechanical shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface in composite beams. Steel pipe as a new shear connector is proposed in this research and its performance to achieve composite strength is investigated. Experimental monotonic push-out tests were carried out for this connector. Then, a nonlinear finite element model of the push-out specimens is developed and verified against test results. Further, the finite element model is used to investigate the effects of pipe thickness, length and diameter on the shear strength of the connectors. The ultimate strengths of these connectors are reported and their respective failure modes are discussed. This paper comprises of the push-out tests of ten specimens on this shear connector in both the vertical and horizontal positions in different reinforced concretes. The results of experimental tests are given as load-deformation plots. It is concluded that the use of these connectors is very effective and economical in the medium shear demand range of 150-350 KN. The dominant failure modes observed were either failure of concrete block (crushing and splitting) or shear failure of pipe connector. It is shown that the horizontal pipe is not as effective as vertical pipe shear connector and is not recommended for practical use. It is shown that pipe connectors are more effective in transferring shear forces than channel and stud connectors. Moreover, based on the parametric study, a formula is presented to predict the pipe shear connectors' capacity.

Monotonic behavior of C and L shaped angle shear connectors within steel-concrete composite beams: an experimental investigation

Mahdi Shariati,Farzad Tahmasbi,Peyman Mehrabi,Alireza Bahadori,Ali Toghroli 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.2

Shear connectors are essential elements in the design of steel-concrete composite systems. These connectors are utilized to prevent the occurrence of potential slips at the interface of steel and concrete. The two types of shear connectors which have been recently employed in construction projects are C- and L-shaped connectors. In the current study, the behavior of C and L-shaped angle shear connectors is investigated experimentally. For this purpose, eight push-out tests were composed and subjected to monotonic loading. The load-slip curves and failure modes have been determined. Also, the shear strength of the connectors has been compared with previously developed relationships. Two failure modes of shear connectors were observed: 1) concrete crushing–splitting and 2) shear connector fracture. It was found that the L-shaped connectors have less shear strength compared to C-shaped connectors, and decreasing the angle leg size increases the shear strength of the C-shaped connectors, but decreases the relative ductility and strength of L-shaped connectors.

매립형 분리식 전단연결재를 적용한 PSC 합성거더의 전단성능 평가

정대성,박세현,임얼 한국복합신소재구조학회 2022 복합신소재구조학회논문집 Vol.13 No.6

When an aged (damaged) concrete deck in a PSC girder composite bridge is replaced, noise and scattering dust due to crushing are generated, in addition to damage to existing shear connectors. Along with these environmental problems, the replacement work takes a long time, and the economic costs significantly increase. This paper proposes a demountable shear connector embedded in a PSC girder to solve these problems. To estimate the shear performance and ultimate behavior of the proposed demountable shear connector, a horizontal-shear experiment was conducted by a parameter study using finite-element analysis. The research analysis confirmed that in the case of having a tapered Y-shaped under a T-sleeve, an initial slip did not occur even with the presence of manufacturing tolerance between the T-sleeve and stud bolt due to the wedge effect, and sufficient initial stiffness was ensured. In addition, the effect of the arrangement direction of the shear connectors was confirmed to do not affect the shear performance. The DY shear-connector model was confirmed to ensure equivalent or better strength performance via a comparative experiment using a conventional rebar-type shear-connector model. The slip displacement also satisfied the ductile design standard of 6 mm or more. Through this study, the demountable shear connector was considered to be a useful alternative for removing and replacing old concrete decks if additional verification such as small-scale composite-girder experiments must be performed. PSC거더 합성교량에 있어 노후(손상)된 바닥판을 교체할 경우에는 기존에 설치된 철근 전단연결재의 손상과 함께 파쇄에 따른 소음 및 비산먼지 등이 많이 발생한다. 이러한 환경적 문제와 함께 교체공사 기간이 길어져 경제적 비용 또한 크게증가한다. 본 연구에서는 이러한 문제를 해결하기 위해 PSC거더에 매립되지만 쉽게 분리할 수 있는 분리식 전단연결재를 제안하였다. 제안한 분리식 전단연결재의 전단강도성능과 파괴거동을 확인하기 위해 유한요소해석을 통한 변수연구와 함께 수평전단실험을 수행하였다. 해석연구를 통해 T-sleeve 하부에 Y형상의 테이퍼진 면을 갖는 경우에 볼트체결력에 따른 쐐기효과로 인해 T-sleeve와 볼트 사이의 제작 공차가 있더라도 초기 슬립이 발생하지 않고 충분한 초기강성을 확보하는 것을 확인하였다. 또한, 전단연결재의 배치 방향에 따른 영향은 전단성능에 영향을 주지 않는 것을 확인하였다. DY전단연결재는 기존 방식인 철근전단연결재 모델과 비교실험을 통해 전단강도성능은 동등 이상을 확보하고 있으며, 슬립변위량 또한 연성설계기준인 6mm 이상을 만족하는 것을 확인하였다. 본 연구를 통해 제안된 분리식 전단연결재는 추가적으로 합성거더 실험 등의 검증을 거친다면노후 바닥판의 철거 및 교체에 유용한 대안이 될 수 있을 것으로 판단된다.

Behaviour and design of stainless steel shear connectors in composite beams

Yifan Zhou,Brian Uy,Jia Wang,Dongxu Li,Xinpei Liu 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.2

Stainless steel-concrete composite beam has become an attractive structural form for offshore bridges and iconic high-rise buildings, owing to the superior corrosion resistance and excellent ductility of stainless steel material. In a composite beam, stainless steel shear connectors play an important role by establishing the interconnection between stainless steel beam and concrete slab. To enable the best use of high strength stainless steel shear connectors in composite beams, high strength concrete is recommended. To date, the application of stainless steel shear connectors in composite beams is still very limited due to the lack of research and proper design recommendations. In this paper, a total of seven pushout specimens were tested to investigate the load-slip behaviour of stainless steel shear connectors. A thorough discussion has been made on the differences between stainless steel bolted connectors and welded studs, in terms of the failure modes, load-slip behaviour and ultimate shear resistance. In parallel with the experimental programme, a finite element model was developed in ABAQUS to simulate the behaviour of stainless steel shear connectors, with which the effects of shear connector strength, concrete strength and embedded connector height to diameter ratio (h/d) were evaluated. The obtained experimental and numerical results were analysed and compared with existing codes of practice, including AS/NZS 2327, EN 1994-1-1 and ANSI/AISC 360-16. The comparison results indicated that the current codes need to be improved for the design of high strength stainless steel shear connectors. On this basis, modified design approaches were proposed to predict the shear capacity of stainless steel bolted connectors and welded studs in the composite beams.

The Shear Behavior of Double-superposed Panels Reinforced with Different Shear Connectors

Wenying Zhang,Lianping Yang,Shaole Yu,Junsheng Yan 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.10

The shear behavior of a new type of sandwich structure, double-superposed panels, is investigated by conducting push-out test and finite element analysis in this paper. Experiments have been carried out to characterize the effect on the shear behavior of two different shear connector configurations: truss connector and tic-tac-toe connector. Based on finite element analysis, a parameter study is conducted, with the major parameters considered being the diameter, height and pitch of shear connector. Test results indicate that the delamination between the precast layers and core layer is the main failure mode for all specimens, and the crack formation and crack development between the two interfaces is not in synch. It’s also revealed that the specimens with tic-tac-toe connections present higher ultimate shear strength, as well as better ductility during the process of failure, compared to those with truss connections. The results of the numerical simulations show that the ultimate shear strength and the ductility of both connector configurations increases as the diameter of the shear connector increases; increasement in height of shear connector has a negligible effect on the shear behavior; when the pitch length is increased, the ultimate shear strength of the truss connector specimen increases, which is the inverse behavior of the specimen with tic-tac-toe connector.

Mechanical characteristics of hollow shear connectors under direct shear force

Kojiro Uenaka,Hiroshi Higashiyama 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.2

The steel-concrete composite decks have high fatigue durability and deformability in comparison with ordinary RC slabs. Withal, the steel-concrete composite deck is mostly heavier than the RC slabs. We have proposed herein a new type of steel-concrete composite deck which is lighter than the typical steel-concrete composite decks. This can be achieved by arranging hollow sectional members as shear connectors, namely, half-pipe or channel shear connectors. The present study aims to experimentally investigate mechanical characteristics of the half-pipe shear connectors under the direct shear force. The shear bond capacity and deformability of the half-pipe shear connectors are strongly affected by the thickness-to-diameter ratio. Additionally, the shear strengths of the hollow shear connectors (i.e. the half-pipe and the channel shear connectors) are compared. Furthermore, shear capacities of the hollow shear connectors equivalent to headed stud connectors are also discussed.