• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.279-282
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• 2005

Experimental study is performed to investigate the variation of shear strength of reinforced concrete beams according to design parameters. The major parameters are loading condition, shear span-to-depth ratio, ratio of tensile longitudinal reinforcement, prestress and boundary rigidity.14 reinforced concrete beams without web reinforcement are tested under monotonic downward loading. The shear strength of the tested specimens were compared with the prediction by design code and Choi's method.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.387-390
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• 2005

Reinforcement corrosion is the principal cause of deterioration of reinforced concrete. It is to be expected that loss of bond between concrete and tension reinforcement would lead to a reduction in shear strength of RC beams designed to fail in shear. This paper presents results of a FE analysis study to evaluate the shear strength of RC beams with exposed reinforcement represented the limiting condition of bond loss.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.389-392
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• 2004

An accurate and rational analytical proposal for determining the shear strengths of interior beam-column joints is presented in this paper. The proposed equation is derived using a compatiblity aided truss model theory. The accuracy of the proposed equation was checked by comparing calculated shear strength of joints with experimental results reported papers in literature. The comparison showed that the proposed equation predicted the experimental shear strength of joints with reasonable agreement.

• Journal of Korean Association for Spatial Structures
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• v.18 no.2
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• pp.121-128
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• 2018

The push-out tests have been conducted on the specimens which consist of the steel beam with U-shape section and the cap-type shear connectors with constant intervals. Existing equations for the evaluation of shear connector strength have been investigated on the basis of test results. The reinforcing bars for longitudinal reinforcement and the penetrative bars for transverse reinforcement didn't have much effect on the shear capacity of the cap-type shear connector. The larger the width of cap-type shear connector was profiled, the greater the shear strength turned. The shear capacities of cap-type shear connectors with constant intervals were evaluated on the basis of push-out test results, and those were possible to be determined with proper safety margin using the Eurocode 4. The slip capacity of cap-type shear connector was shown to exceed the limit value of 6mm for sufficiently ductile behavior.

• Tunnel and Underground Space
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• v.17 no.3 s.68
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• pp.186-196
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• 2007

In this study, direct shear tests were carried out on the 30 rock joint samples in order to investigate the influence of roughness and normal stress on the shear behaviour. Joint roughness profiles were measured by use of 3D laser profiler, and then the samples were equally classified into three individual groups according to the roughness index of rock joints. Peak shear strength, residual shear strength, shear stiffness, dilation angle of rock joints were investigated in condition of five different constant normal load. Peak shear strength was increased as roughness index was increased, and the influence of roughness on strength was found to be more considerable in case of lower normal stress condition. Residual shear strength and shear stiffness were increased as roughness index and normal stress were increased. Finally dilation angle was decreased as normal stress was increased, but it was increased as roughness index was increased in the same normal stress condition.

• Steel and Composite Structures
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• v.46 no.1
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• pp.75-92
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• 2023

The novel composite cold-formed steel (CFS)/engineered cementitious composites (ECC) beams have been recently presented. The new composite section exhibited superior structural performance as a flexural member, benefiting from the lightweight thin-walled CFS sections with improved buckling and torsional properties due to the restraints provided by thinlayered ECC. This paper investigated the shear performance of the new composite CFS/ECC section. Twenty-eight simply supported beams, with a shear span-to-depth ratio of 1.0, were assembled back-to-back and tested under a 3-point loading scheme. Bare CFS, composite CFS/ECC utilising ECC with Polyethylene fibres (PE-ECC), composite CFS/MOR, and CFS/HSC utilising high-strength mortar (MOR) and high-strength concrete (HSC) as replacements for PE-ECC were compared. Different failure modes were observed in tests: shear buckling modes in bare CFS sections, contact shear buckling modes in composite CFS/MOR and CFS/HSC sections, and shear yielding or block shear rupture in composite CFS/ECC sections. As a result, composite CFS/ECC sections showed up to 96.0% improvement in shear capacities over bare CFS, 28.0% improvement over composite CFS/MOR and 13.0% over composite CFS/HSC sections, although MOR and HSC were with higher compressive strength than PE-ECC. Finally, shear strength prediction formulae are proposed for the new composite sections after considering the contributions from the CFS and ECC components.

• Steel and Composite Structures
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• v.46 no.2
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• pp.175-193
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• 2023

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 Journal of Advanced Prosthodontics
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• v.7 no.1
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• pp.69-75
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• 2015

PURPOSE. To compare the shear bond strength of various veneering materials to grade II commercially pure titanium (CP-Ti). MATERIALS AND METHODS. Thirty specimens of CP-Ti disc with 9 mm diameter and 10 mm height were divided into three experimental groups. Each group was bonded to heat-polymerized acrylic resin (Lucitone 199), porcelain (Triceram), and indirect composite (Sinfony) with 7 mm diameter and 2 mm height. For the control group (n=10), Lucitone 199 were applied on type IV gold alloy castings. All samples were thermocycled for 5000 cycles in $5-55^{\circ}C$ water. The maximum shear bond strength (MPa) was measured with a Universal Testing Machine. After the shear bond strength test, the failure mode was assessed with an optic microscope and a scanning electron microscope. Statistical analysis was carried out with a Kruskal-Wallis Test and Mann-Whitney Test. RESULTS. The mean shear bond strength and standard deviations for experimental groups were as follows: Ti-Lucitone 199 ($12.11{\pm}4.44$ MPa); Ti-Triceram ($11.09{\pm}1.66$ MPa); Ti-Sinfony ($4.32{\pm}0.64$ MPa). All of these experimental groups showed lower shear bond strength than the control group ($16.14{\pm}1.89$ MPa). However, there was no statistically significant difference between the Ti-Lucitone 199 group and the control group, and the Ti-Lucitone 199 group and the Ti-Triceram group. Most of the failure patterns in all experimental groups were adhesive failures. CONCLUSION. The shear bond strength of veneering materials such as heat-polymerized acrylic resin, porcelain, and indirect composite to CP-Ti was compatible to that of heatpolymerized acrylic resin to cast gold alloy.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.5
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• pp.502-513
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• 2001

The purpose of this study was to evaluate the effect of dentin pretreatment with Dentin Conditioner, Ultra-Etch, conditioner of Fuji Plus cement on the shear bond strength of resin-reinforced glass ionomer cements to dentin and analyze the fractured surfaces. To evaluate the bond strength, the extracted human teeth which had uniform area of exposed dentin were cemented with conventional glass ionomer cement, 3M $RelyX^{TM}$ Luting (Vitremer luting cement), Fuji Plus cement after dentin pretreatment. The shear bond strength was measured using the Universal testing machine (Instron Co., USA) with a crosshead speed of 1mm/m. The effect of dentin pretreatment was evaluated by observing pretreated dentin surfaces under the scanning electron microscope, measuring the shear bond strength and observing the fractured surfaces under the scanning electron microscope. The results were as follows : On the SEM observation of surface morphology, the specimens treated with Dentin Conditioner. Ultra-Etch and conditioner of Fuji Plus cement were removed the smear layer and funneled dentinal tubules in dentin surfaces. In $RelyX^{TM}$ Luting cement group, shear bond strength of pretreated group was significantly higher than control group. In Fuji Plus cement group and Fuji I group, regardless of the type of pretreatment agents, there was tendency of increase in the shear bond strength. On the SEM observation of fractured surfaces, as the shear bond strength increase, it were shown thicker cement layers and were not shown dentinal tubules According to these results. it were shown that dentin pretreatment have much effect on bonding states.

• Steel and Composite Structures
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• v.45 no.6
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• pp.797-818
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• 2022

Steel-precast ultra-high-performance concrete (UHPC) composite beams with demountable high-strength friction-grip bolt (HSFGB) shear connectors can be used for accelerated bridge construction (ABC) and achieve excellent structural performance, which is expected to be dismantled and recycled at the end of the service life. However, no investigation focuses on the demountability and reusability of such composite beams, as well as the installation difficulties during construction. To address this issue, this study conducted twelve push-out tests to investigate the effects of assembly condition, bolt grade, bolt-hole clearance, infilling grout and pretension on the crack pattern, failure mode, load-slip/uplift relationship, and the structural performance in terms of ultimate shear strength, friction resistance, shear stiffness and slip capacity. The experimental results demonstrated that the presented composite beams exhibited favorable demountability and reusability, in which no significant reduction in strength (less than 3%) and stiffness (less than 5%), but a slight improvement in ductility was observed for the reassembled specimens. Employing oversized preformed holes could ease the fabrication and installation process, yet led to a considerable degradation in both strength and stiffness. With filling the oversized holes with grout, an effective enhancement of the strength and stiffness can be achieved, while causing a difficulty in the demounting of shear connectors. On the basis of the experimental results, more accurate formulations, which considered the effect of bolt-hole clearance, were proposed to predict the shear strength as well as the load-slip relationship of HSFGBs in steel-precast UHPC composite beams.