• Advances in concrete construction
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• v.7 no.4
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• pp.219-229
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• 2019

This paper presents an experimental study on the structural performance of an innovative ultra-high performance fiber reinforced concrete (UHPFRC) deck with coarse aggregate of composite bridge under shear force. Test parameters included curing method and shear span-to-height ratio. Test results indicated that more short fine cracks developed beside the existing cracks due to the randomly dispersed fibers, resulting in re-distributing and homogenizing of the concrete stress beside cracks and allowing for the occurrence of more cracks with small spacing compared to normal strength concrete beams. Curing methods, incorporating steam curing and natural curing, did not have obvious effect on the nominal bending cracking strength and the ultimate strength of the test specimens. Shear reinforcement need not be provided for UHPFRC decks with a fiber volume fraction of 2%. UHPFRC decks showed superior load resistance ability after the appearance of cracks and excellent post-cracking deformability. Lastly, the current shear provisions were evaluated by the test results.

• International journal of steel structures
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• v.18 no.5
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• pp.1784-1800
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• 2018

Tension-shear loading is a common loading condition in steel structures during the earthquake shaking. To study ductile fracture in structural steel under multiple stress states, experimental investigations on the different fracture mechanisms in Chinese Q235 steel were conducted. Different tension-shear loading conditions achieved by using six groups of inclined notch butterfly configurations covering pure shear, tension-shear and pure tension cases. Numerical simulations were carried out for all the specimens to determine the stress and strain fields within the critical sections. Two tension-shear fracture models were calibrated based on the hybrid experimental-numerical procedure. The equivalent fracture strain obtained from the round bar under tensile loading was used for evaluating these two models. The results indicated that the tension-shear criterion as a function of the shear fracture parameter had better performance in predicting the fracture initiation of structural steel under different loading conditions.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.88-91
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• 2004

It is generally known that the bonding strength of RC(Reinforced Concrete) flexural members strengthened by fiber sheet composites are sufficient and the bonding failure does not occur until the sheet failed. However, many researchers have been reported that, before the failure of the sheet, the bonding failure happens even though the bonding length is sufficient. This study was carried out to evaluate the effectiveness of shear key and U strip on flexural behavior of reinforced concrete beam structures. The ply number of CFS(Carbon Fiber Sheet), location of shear key, and existence or not of U strip were selected as the main test variables. Test results show that the behavior of a beam of which shear key is located in the nearby. of support and U strip is not existent, and having CFS of 1 ply is mostly improved.

• Journal of the Korean Society for Railway
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• v.19 no.3
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• pp.341-350
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• 2016

Concrete track on railway bridges should be designed to effectively respond to the movement of the superstructure of the bridge. In the design procedure, shear keys are generally placed on the protection concrete layer (PCL) before casting the concrete track so the shear force due to slip between the concrete track and the bridge super-structure can be transferred. In this paper, a nonlinear structural analysis procedure that considers the construction joint has been developed to predict the shear behavior of a shear key. With the developed analysis procedure, it was possible to predict the shear force-shear slip response at the construction joint in a shear key by considering the friction of concrete surface and the dowel action of the rebars. The analysis results showed good agreement with the test results for 4 specimens.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.04a
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• pp.86-89
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• 1992

In the precast segmental method of construction, segments of a structure are precast, assembled, and tied together by post-tensioning to form the structure. Shear strength and behavior of points in precast concrete structures are important problems in the design of these structures. An experimental program was set up study the shear behavior of precast concrete shear keys. experimental models of keyed joints include a single key, representing one of a series include the shear key shape, d/h ratio(1/4, 1/5, 1/7), and inclined angle (45。 60。 75。). Two different types of joints, i.e., epoxied joint and dry joints were studied. From the present tests, it is found that epoxied joints have higher shear strength than those of dry joints, and that high d/h ratio keys have higher shear strength than those of low d/h ratio keys. The keys with 60。-inclined angle shows the highest shear strength among various angles.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.158-161
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• 2006

The numerical analysis and the experiment was performed to investigate the influences of shear connector on shear resistance capability. The numerical analysis's results should that the H/B ratio of shear key is more effective than angle of shear key against shear strength and shear behavior, and it is more desirable to use a half of the H/B ratio of shear key. The specimen was made with same condition as AASHTO recommended. There model tests were performed under various form of shear key, number, arrangement reinforcement and condition using epoxy. As a result of the experiment, there is little difference(or there is no difference) between the case of using epoxy on shear connector and the unused case.

• Advances in concrete construction
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• v.5 no.5
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• pp.469-479
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• 2017

Balanced cantilever construction is extensively used in the construction of prestressed concrete (PSC) box-girder bridges. Shear-lag effect is usually considered in finished bridges, while the cumulative shear-lag effect in bridges during balanced cantilever construction is considered only rarely. In this paper, based on the balanced cantilever construction sequences of large-span PSC box-girder bridges, the difference method is employed to analyze the cumulative shear-lag effect of box girders with varying depth under the concrete segments' own weight. During cantilever construction, no negative shear-lag effect is generated, and the cumulative shear-lag effect under the balanced construction procedure is greater than the instantaneous shear-lag effect in which the full dead weight is applied to the entire cantilever. Three cross-sections of Jianjiang Bridge were chosen for the experimental observation of shear-lag effect, and the experimental results are in keeping with the theoretical results of cumulative shear-lag effect. The research indicates that only calculating the instantaneous shear-lag effect is not sufficiently safe for practical engineering purposes.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.155-163
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• 2013

This study explores the structural behavior of module joints in floating concrete structures subjected to shear. Crack patterns, shear behavior and shear capacity of shear keys in joints of concrete module were investigated. Test parameters included shear key shape, or inclination of shear keys, confining stress levels and compressive strength of concrete. Test results showed that shear strength of joints increased as shear key inclination increased. Test results also showed that shear strength of concrete module joints increased with the increase of confining stress levels. The equation for predicting shear strength of joints was suggested, which was based on the test results. Shear strength prediction by using the equation suggested in this study showed good agreement with test results.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3251-3255
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• 2011

Being the concrete track laid on bridge, due to track-bridge temperature difference, traction and brake force, and nosing force, the horizontal force can be applied to the track slab. Therefore, shear key structures to resist this horizontal force should be installed. The shear key structures installed in the Kyeong-Bu high-speed line are consisted of four shear keys at every slab with the length of 6 to 8m. However, in the point of view of construction, it is more advantageous to curtail the numbers of shear keys, and thus, the numbers and spacing of the shear keys should be carefully determined. In this study, hence, the effects of slab length, the numbers and spacing of the shear keys on design of shear key and track slab are examined.

• Geomechanics and Engineering
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• v.11 no.3
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• pp.361-372
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• 2016

The soil-concrete interface shear strength, although has been extensively studied, is still difficult to predict as a result of the dependence on many factors such as normal stresses, surface roughness, particle sizes, moisture contents, dilation angles of soils, etc. In this study, a well-known rigorous statistical learning approach, namely the least squares support vector machine (LS-SVM) realized in a ubiquitous spreadsheet platform is firstly used in estimating the soil-structure interface shear strength. Instead of studying the complicated mechanism, LS-SVM enables to explore the possible link between the fundamental factors and the interface shear strengths, via a sophisticated statistic approach. As a preliminary investigation, the authors study the expansive soils that are found extensively in most countries. To reduce the complexity, three major influential factors, e.g., initial moisture contents, initial dry densities and normal stresses of soils are taken into account in developing the LS-SVM models for the soil-concrete interface shear strengths. The predicted results by LS-SVM show reasonably good agreement with experimental data from direct shear tests.