• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.1091-1096
• /
• 2001

Generally, in a steel girder and the concrete slab act as a composite structure, the connectors must have adequate strength and stiffness. If there are no horizontal or vertical separations at the interface, the connectors are described as rigid, and complete interaction can be said to exist under these idealized circumstances. In previous study, it was considered that the strength of stud is affected by the stud diameter, height of stud and compressive strength of concrete. The differences between previous study and this study are variables, which are shank diameter of shear connector, the spacing of shear connector, the size of specimen and the row of shear connector. So this paper, as a study on the strength of shear connector with the spacing of shear connector, size of specimen (block-out size), row of shear connector and shank diameter of shear connector resulted from the push-out specimen are conducted with ABAQUS program. It is to investigate the effects of characteristics of these factors. The load-slip relations obtained from the experiments are compared with those of analyses. From these results, the trends of stress are stress estimated and compared with push-out test.

• Steel and Composite Structures
• /
• v.26 no.3
• /
• pp.375-386
• /
• 2018

Existing design codes for steel-concrete composite structures give only general information about the shear connection provided by headed studs in group arrangement. Grouting of the openings in prefabricated concrete slabs, where the grouped headed studs are placed in the deck pockets is alternative to cast-in-place decks to accomplish fast execution of composite structures. This paper considers the possibility to reduce the distance between the studs within the group, bellow the Eurocode limitations. This may lead to increased competitiveness of the prefabricated construction because more studs are placed in the group if negative effectives of smaller distances between studs are limited. The main purpose of this work is to investigate these limits and propose an analytical calculation model for prediction of the shear resistance of grouped stud arrangements in the deck pockets. An advanced FEA model, validated by results of push-out experiments, is used to analyze the shear behavior of the grouped stud with smaller distance between them than recommended by EN 1994-1. Calculation model for shear resistance, which is consistent with the existing Eurocode rules, is proposed based on a newly introduced equivalent diameter of the stud group, $d_G$. The new calculation model is validated by comparison to the results of FE parametric study. The distance between the studs in the longitudinal direction and the number of stud rows and columns in the group are considered as the main variables.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.2
• /
• pp.229-236
• /
• 2011

This study was conducted to understand the characteristics of the compression behavior of steel plate-concrete(SC) structures with a width-to-thickness ratio under axial loading. SC structures are structural systems where concrete is poured into steel plates to which headed stud bolts had been attached inside. The specimens were classified according to the two width-to-thickness (W/T) ratios of 1.60 and 3.56. Through these experiments, the following conclusions could be arrived at. The fracture pattern of the specimens showed that steel plate buckling occurred between the stud lines, and that a crack occurred at the concrete spalling from the sides of the concrete before the system reached the maximum compressive strength. The maximum compressive strength of the specimens was larger than that of the existing equations (AISC 2005, ACI 318-05, and KBC 2005). With the increased W/T ratio of the specimens, the strength of the concrete core was decreased to account for the confinement effects from the steel plates.

• Journal of the Korea Concrete Institute
• /
• v.27 no.6
• /
• pp.677-685
• /
• 2015

In a will to subdue the brittleness as well as the low tensile and flexural strengths of ordinary concrete, researches are being actively watched worldwide on steel fiber-reinforced Ultra High Performance Concrete (UHPC) obtained by admixing steel fibers in ultra high strength concrete. For the purpose of maximizing advantage of UHPC, this study removes the upper flange of the steel girder to apply an inverted T-shape girder for the formation of the composite beam. This paper intends to evaluate the behavior of the shear connectors and the flexural characteristics of the composite beam made of the inverted T-shape girder and UHPC slab using 16 specimens considering the compressive strength of concrete, the mixing ratio of steel fiber, the spacing of shear connectors and the thickness of the slab as variables. In view of the test results, it seemed that the appropriate stud spacing should range between 100 mm and 2 or 4 times the thickness of the slab. Moreover, the relative displacement observed in the specimens showed that ductile behavior was secured to a certain extent with reference to the criteria for ductile behavior suggested in Eurocode-4. The specimens with large stud spacing exhibited larger values than given by the design formula and revealed that the shear connectors developed larger ultimate strength than predicted owing to the action of UHPC and steel after non-composite behavior. Besides, the specimens with narrow stud spacing failed suddenly through compression at the upper chord of UHPC before reaching the full capacity of the shear connectors.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.4A
• /
• pp.457-463
• /
• 2008

The longitudinal stiffener performs its role to increase the local buckling strength by making simple support upon compression flange. In the recent researches, it is investigated that compression flange with point supports on certain arrangement reveals the same strength with longitudinal stiffeners. From this results, it is predictable that shear stud could perform the role of longitudinal stiffener if shear stud embedded in concrete satisfies the requirement to point-support under yield stress of the compression flange. In this study, the researches were performed to investigate the optimally required arrangement space of longitudinal point-support for which the shear stud replacing the longitudinal stiffeners and simultaneously determine the required numbers and space of shear stud for completely composite behavior between compression bottom flange and bottom concrete on the double composite girder system.

• Journal of Korean Society of Steel Construction
• /
• v.16 no.4 s.71
• /
• pp.425-432
• /
• 2004

Large studs were suggested not only for the design of steel-concrete composite bridges with simplified sections but also for the shear connection in precast decks requiring uniform distribution of shear pockets. Based on the push-out test results on studs with diameters of more than 25 mm, partial composite beams with 40%-degree shear connection were fabricated, and static tests were performed. The ultimate strength and horizontal shear load redistribution of partial composite beams, which have parameters of stud shank diameters and distribution, were evaluated, and group failure in the shear span was observed. Since the flexural strength of composite beams are dependent on the strength of their shear connection, the strength of the stud connection was estimated and it showed considerably higher shear strength. From the load-slip curves, the sufficient ductility and load redistribution of large studs were confirmed. Uniformly distributed large studs can provide proper ultimate behavior of composite beams.

• Journal of the Korea Concrete Institute
• /
• v.26 no.6
• /
• pp.761-769
• /
• 2014

Ultra high performance concrete (UHPC) has been developed to overcome the low strengths and brittleness of conventional concrete. Considering that UHPC, owing to its composition and the use of steel fibers, develops a compressive strength of 180 MPa as well as high stiffness, the top flange of the steel girder may be superfluous in the composite beam combining a slab made of UHPC and the steel girder. In such composite beam, the steel girder takes the form of an inverted-T shaped structure without top flange in which the studs needed for the composition of the steel girder with the UHPC slab are disposed in the web of the steel girder. This study investigates experimentally and analytically the flexural behavior of this new type of composite beam to propose details like stud spacing and slab thickness for further design recommendations. To that goal, eight composite beams with varying stud spacing and slab thickness were fabricated and tested. The test results indicated that stud spacing running from 100 mm to 2 to 3 times the slab thickness can be recommended. In view of the relative characteristic slip limit of Eurocode-4, the results showed that the composite beam developed ductile behavior. Moreover, except for the members with thin slab and large stud spacing, most of the specimens exhibited results different to those predicted by AASHTO LRFD and Eurocode-4 because of the high performance developed by UHPC.

• Journal of Korean Society of Steel Construction
• /
• v.20 no.2
• /
• pp.227-236
• /
• 2008

The kind of concrete generally used in steel concrete composite bridges is normal-weight concrete whose unit weight is ${2,300kg/m^{3}}$. However, using lightweight concrete in composite bridges diminishes the sectional forces due to the self-weight of concrete decks. As a result, this will make the bridge design more economical. The type of concrete deck that could be adopted in composite bridges using lightweight con crete may be classified into Cast-In-Place (C.I.P.) concrete deck and precast concrete deck. These two types of decks have some differences with respect to structural behavior and constructional method, and hence,structural behavior of stud shear connectors that connect a concrete deck to a steel girder is changed with the type of deck used. In this study, push-out tests were conducted to evaluate the characteristics of static behavior of the stud shear connectors with a precast deck using lightweight concrete. Also, additional precast deck specimens with bedding layer that had shear keys and devices for transverse confinement of the bedding layer for the prevention of cracks occurring in the bedding layer were tested. These cracks The efficiency of these devices was then evaluated.

• Journal of Korean Society of Steel Construction
• /
• v.20 no.2
• /
• pp.333-345
• /
• 2008

concrete deck bridges are increasingly aplied to twin- girder bridges and open-stel box girder bridges.One of the most dificult isues in the design of shear conect ors is the mater of achieving ful composite action. Many connectors in smal area require a significant section los of precast decks resulting in difficult reinforcement details. In this closer spacing than the required minimum spacing in the design codes was evaluated through static tests. Test results s howed that the ultimate strength decreased as the conector spacing was reduced. The strength enhancement was observed due to aditional reinforcement for precast slabs or for shear pockets. Thus, the design of group stud shear connection needs to anticipate failure modes and the conector failure should be induced. Based on the test results, an empirical equation consi dering stud spacing was proposed to evaluate the ultimate strength of group stud shear conection. Fatigue tests showed n o reduction in fatigue life of the group stud shear conection in the range of this research. Details of the precast decks wer e enhanced using the findings of the study.

• Earthquakes and Structures
• /
• v.4 no.6
• /
• pp.629-647
• /
• 2013

Loading protocols have been developed for quasi-static cyclic testing of structures and components. However, it is uncertain if protocols developed for conditions of intense ground shaking in regions of high seismicity would also be applicable to regions of low-moderate seismicity that are remote from the tectonic plate boundaries. This study presents a methodology for developing a quasi-static cyclic displacement loading protocol for experimental bracing evaluation of cold-formed steel stud shear walls. Simulations presented in the paper were based on conditions of moderate ground shaking (in Australia). The methodologies presented are generic in nature and can be applied to other regions of similar seismicity conditions (which include many parts of China, Korea, India and Malaysia). Numerous response time histories including both linear and nonlinear analyses have been generated for selected earthquake scenarios and site classes. Rain-flow cycle counting method has been used for determining the number of cycles at various ranges of normalized displacement amplitude. It is found that the number of displacement cycles of the loading protocol increases with increasing intensity of ground shaking (associated with a longer return period).