• Structural Engineering and Mechanics
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• v.34 no.2
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• pp.175-188
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• 2010

This paper deals with the buckling and postbuckling responses, and the progressive failure of square laminates of symmetric lay-up with a central rectangular cutout under in-plane shear load. A detailed investigation is made to show the effects of cutout size and cutout aspect ratio on the buckling and postbuckling responses, failure loads and failure characteristics of $(+45/-45/0/90)_{2s}$, $(+45/-45)_{4s}$ and $(0/90)_{4s}$ laminates. The 3-D Tsai-Hill criterion is used to predict the failure of a lamina while the onset of delamination is predicted by the interlaminar failure criterion. In addition, the effects of boundary conditions on buckling loads, failure loads, failure modes, and maximum transverse deflection for a $(+45/-45/0/90)_{2s}$ laminate with and without a square cutout have been presented. It is concluded that because of early onset of delamination at the net section of cutouts before first-ply failure, total strength of the laminate with very small cutouts can not be utilized.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.256-267
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• 2006

After heavy rainfall, It was occurred massive plane failure along bedding plane of shale in the center of rock slope. It was observed filling material and trace of underground water leakage around of the slope. We tried to find the cause for slope failure, and the result of examination showed that primary factors of the failure were low shear strength of clay filling material and water pressure farmed within tension crack existed in the top of the slope. In this research, in order to examine the features of shear strength of filled rock joint, shear test of filled rock joint was conducted using of artificial filling material such as sand and clay. Also we made an investigation into the characteristics of shear strength with different thickness of filling materials.

• Journal of Korean Society of Steel Construction
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• v.24 no.2
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• pp.137-147
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• 2012

This paper describes an experimental study on the mechanical characteristic and behavior of a structure that has a joint between the reinforced concrete (RC) member and steel plate concrete (SC) member. An out-of-plane flexural test on an L-type test specimen and in-plane shear test on an I-type test specimen were carried out by means of repeated cyclic loading until their failure. Based on the results, the former showed pull-out failure mode of anchored vertical bars while the latter exhibited flexural failure mode of the basement member. These results reveal that the maximum capacity of the specimens is 96% and 82%, respectively, compared with the theoretical value.

• Computers and Concrete
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• v.8 no.6
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• pp.735-755
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• 2011

The capability of a multi-directional fixed smeared crack constitutive model to simulate the flexural/punching failure modes of fiber reinforced concrete (FRC) laminar structures is discussed. The constitutive model is implemented in a computer program based on the finite element method, where the FRC laminar structures were simulated according to the Reissner-Mindlin shell theory. The shell is discretized into layers for the simulation of the membrane, bending and out-of-plane shear nonlinear behavior. A stress-strain softening diagram is proposed to reproduce, after crack initiation, the evolution of the normal crack component. The in-plane shear crack component is obtained using the concept of shear retention factor, defined by a crack-strain dependent law. To capture the punching failure mode, a softening diagram is proposed to simulate the decrease of the out-of-plane shear stress components with the increase of the corresponding shear strain components, after crack initiation. With this relatively simple approach, accurate predictions of the behavior of FRC structures failing in bending and in shear can be obtained. To assess the predictive performance of the model, a punching experimental test of a module of a façade panel fabricated with steel fiber reinforced self-compacting concrete is numerically simulated. The influence of some parameters defining the softening diagrams is discussed.

• Earthquakes and Structures
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• v.22 no.4
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• pp.355-372
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• 2022

The study is part of an experimental program on full-scale Un-Reinforced Masonry (URM) wall panels strengthened with Textile reinforced mortars (TRM). Eight brick walls (two with and five without central opening), were tested under the diagonal tension (shear) test method in order to investigate the strengthening system effectiveness on the in-plane behaviour of the walls. All the URM panels consist of the innovative components, named "Orthoblock K300 bricks" with vertical holes and a thin layer mortar. Both of them have great capacity and easy application and can be constructed much more rapidly than the traditional bricks and mortars, increasing productivity, as well as the compressive strength of the masonry walls. Several parameters pertaining to the in-plane shear behaviour of the retrofitted panels were investigated, including shear capacity, failure modes, the number of layers of the external TRM jacket, and the existence of the central opening of the wall. For both the control and retrofitted panels, the experimental shear capacity and failure mode were compared with the predictions of existing prediction models (ACI 2013, TA 2000, Triantafillou 1998, Triantafillou 2016, CNR 2018, CNR 2013, Eurocode 6, Eurocode 8, Thomoglou et al. 2020). The experimental work allowed an evaluation of the shear performance in the case of the bidirectional textile (TRM) system applied on the URM walls. The results have shown that some analytical models present a better accuracy in predicting the shear resistance of all the strengthened masonry walls with TRM systems which can be used in design guidelines for reliable predictions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.4
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• pp.94-101
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• 2010

Recently, the interest of precast concrete is increased for rapid construction in construction fields. Experimental study about the shear performance of the joint between hollow core slabs which have internal core to reduce their weight was performed. Main test variables were thickness of the topping concrete and existence of the wiremesh. Total 8 specimens including 4 in-plane shear and 4 out of plane shear were tested. Test results were analyzed in terms of cracking load, failure load, failure aspect, stiffness and ductility, and compared its design load to develop optimum design details. Test results indicated that the shear performance of the non-shrinkage mortar specimen was similar to that of 30mm thickness topping concrete specimen, and the effect of wiremesh reinforcement did not affect the failure load or stiffness of the specimens but the increase of ductility. And this paper presents the comparison results of the test results and design load to provide the optimum detail of the joint design between the hollow core slabs.

• Tunnel and Underground Space
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• v.16 no.5 s.64
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• pp.368-376
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• 2006

After heavy rainfall, It was occurred massive plane failure along bedding plane of shale in the center of rock slope. It was observed filling material and trace of underground water leakage around of the slope. We tried to find the cause for slope failure, and the result of examination showed that primary factors of the failure were low shear strength of clay filling material and water pressure formed within tension crack existed in the top of the slope. In this research, in order to examine the features of shear strength of filled rock joint, shear test of filled rock joint was conducted using of artificial filling material such as sand and clay..Also we made an investigation into the characteristics of shear strength with different thickness of filling materials.

• Journal of the Korean Geotechnical Society
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• v.32 no.3
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• pp.49-60
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• 2016

Soil failure is initiated and preceded by forming and progressing of shear band, defined as the localization of deformation into thin zones of soil mass. To understand the failure mechanism of normally consolidated cohesive soil, the spatial distribution and evolution of deformation within the entire specimen need to be evaluated. In this study, vertical compression tests under plane strain condition were performed on reconstituted kaolinite specimens, while capturing digital images of the specimen at regular intervals during shearing. Overall stress-strain behavior from initial to post peak has been analyzed together with spatial distributions of deformations and shear band characteristics from digital images at 4 stages.

• Geomechanics and Engineering
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• v.13 no.3
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• pp.431-446
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• 2017

Rock bridges in rock masses would increase the bearing capacity of Non-persistent discontinuities. In this paper the effect of ratio of rock bridge surface to joint surface, rock bridge shape and normal load on failure behaviour of intermittent rock joint were investigated. A total of 42 various models with dimensions of $15cm{\times}15cm{\times}15cm$ of plaster specimens were fabricated simulating the open joints possessing rock bridge. The introduced rock bridges have various continuities in shear surface. The area of the rock bridge was $45cm^2$ and $90cm^2$ out of the total fixed area of $225cm^2$ respectively. The fabricated specimens were subjected to shear tests under normal loads of 0.5 MPa, 2 MPa and 4 MPa in order to investigate the shear mechanism of rock bridge. The results indicated that the failure pattern and the failure mechanism were affected by two parameters; i.e., the ratio of joint surface to rock bridge surface and normal load. So that increasing in joint area in front of the rock bridge changes the shear failure mode to tensile failure mode. Also the tensile failure change to shear failure by increasing the normal load.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.743-748
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• 2010

The stability forecasting of rock slope is more difficult than soil slope because catching the sign of failure in monitoring is not easy and deformation of the rock is small in failure process. But in the rock slope, there is small deformation like crack propagation in rock itself and it accumulates gradually in failure process. If it is possible to detect the small change in the rock slope, we can know the failure time exactly. Because the individual signal is gathered in the acoustic emission monitoring, it is possible to monitoring the slope if many sound signal is accumulated. Detection test of acoustic emission was performed. Uniaxial, two types of bending test, and two plane shear test were done with various cement paste sample. Wave propagation velocity of uniaxial test sample was increased with curing time. Wave Analysis give us the result that there is a AE sign signal before the failure, the AE count is suddenly increased. And frequency level 125kHz before failure is changed to level 200-250kHz after failure. In two plane shear test we can catch the AE signal and can know the failure type from wave shape. Monitoring test site is tunnel slope in Hongcheon but special signal is not collected.