• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.280-285
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• 2008

Two kinds of failure model, that is, the Gurson model and a shear failure model were used for the finite element analyses of simple and notch tensile specimens and axial compression of a fracture tube with initial saw-cuts. The parameter values for the shear failure model were determined by a combined experimental and numerical analysis of the notch tensile specimens. After fitting the numerical parameters such as the yielding stress and the fracture shear strains, the Gurson model and the shear failure model were applied to the analysis of the fracture tube. Although the Gurson model and the shear failure model showed similar fracture behavior for the case of the tensile specimens, the respective results were different in the axial force and the crack growth rate of the fracture tube. That is, the shear failure model required more axial force to make the cracks propagate along the tube than the Gurson model. These are believed to show the lack of damage evolution process of the shear failure model. To decide which model is better in the tube analysis, experimental verification will be necessary.

• Steel and Composite Structures
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• v.44 no.6
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• pp.883-898
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• 2022

A hollow-core partially-encased composite beam, named HPEC beam, is investigated in this paper. HPEC beam comprises I-beam, longitudinal reinforcement, stirrup, foam formwork, and cementitious grout. The foam formwork is located on both sides of the web, and cementitious grout is cast within the steel flange. To investigate the shear performance of HPEC beams, static loading tests of six HPEC beams and three control beams were conducted. The shear span ratio and the number of studs on the shear behavior of the HPECspecimens were studied. The failure mechanism was studied by analyzing the curves of shear force versus both deflection and strain. Based on the shear span ratio (𝜆), two typical shear failure modes were observed: shear compression failure when 1.6 ≤ 𝜆 ≤ 2; and diagonal compression failure when 𝜆 ≤ 1.15. Shear studs welded on the flange can significantly increase the shear capacity and integrity of HPEC beams. Flange welded shear studs are suggested. Based on the deformation coordination theory and superposition method, combined with the simplified modified compression field model and the Truss-arch model, Modified Deformation Coordination Truss-arch (M.D.C.T.) model was proposed. Compared with the shear capacity from YB9038-2006 and JGJ138-2016, the calculation results from M.D.C.T. model could provide reasonable predictions.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.35-46
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• 2000

In this paper, an analytical model is proposed to predict the shear strenth of RC beams strengthened by FRP. This predictional model is composed of two basic models-the upper bound theorem for shear failure (shear tension or shear compression criteria) and a truss model based on the lower bound theorem for diagonal tension creteria. Also, a simple flexural theory based on USD is used to explain flexural failure. The major cause of destruction of RC beams shear strengthened by FRP does not lie in FRP fracture but in the loss of load capacity incurred by rip-off failure of shear strengthening material. Since interfacial shear stree between base concrete and the FRP is a major variable in rip-off failure mode, it is carefully analyzed to derive the shear strengthening effect of FRP. The ultimate shear strength and failure mode of RC beams, using different strengthening methods, estimated in this predictional model is then compared with the result derived from destruction experiment of RC beams shear strengthened using FRP. To verify the accuracy and consistency of the analysis, the estimated results using the predictional model are compared with various other experimental results and data from previous publications. The result of this comparative analysis showed that the estimates from the predictional model are in consistency with the experimental results. Therefore, the proposed shear strength predictional model is found to predict with relative accuracy the shear strength and failure mode of RC beams shear strengthened by FRP regardless of strengthening method variable.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.2
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• pp.113-119
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• 2024

Existing reinforced concrete buildings with seismically deficient column details affect the overall behavior depending on the failure type of column. This study aims to develop and validate a machine learning-based prediction model for the column failure modes (shear, flexure-shear, and flexure failure modes). For this purpose, artificial neural network (ANN), K-nearest neighbor (KNN), decision tree (DT), and random forest (RF) models were used, considering previously collected experimental data. Using four machine learning methodologies, we developed a classification learning model that can predict the column failure modes in terms of the input variables using concrete compressive strength, steel yield strength, axial load ratio, height-to-dept aspect ratio, longitudinal reinforcement ratio, and transverse reinforcement ratio. The performance of each machine learning model was compared and verified by calculating accuracy, precision, recall, F1-Score, and ROC. Based on the performance measurements of the classification model, the RF model represents the highest average value of the classification model performance measurements among the considered learning methods, and it can conservatively predict the shear failure mode. Thus, the RF model can rapidly predict the column failure modes with simple column details.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.393-396
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• 1999

This paper presents a truss model for RC columns subjected to axial load and lateral load. The presented model is based on a stress field for the flexural-shear failure of short columns, which represent shear failure and bond splitting failure. Using this model, failure strength and related deformation of RC columns are investigated. Particular emphasis is placed on models capable of representing the interaction between deformation and shear strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.271-274
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• 2005

Existing strut-and-tie model cannot be applied to analysis of slender beams without shear reinforcement because shear transfer mechanism is not formed. In the present study, a new strut-and-tie model with rigid joint was developed. Basically, concrete strut is modeled as a frame element which can transfer shear force (or moment) as well as axial force. Employing Rankine failure criterion, failure strength due to shear-tension and shear-compression developed in compressive concrete strut was defined. For verification, various test specimens were analyzed and the results were compared with tests. The proposed strut-and-tie model predicted shear strength and failure displacement with reasonable precision, addressing the design parameters such as shear reinforcement, concrete compressive strength, and shear span ratio.

• Journal of Ocean Engineering and Technology
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• v.21 no.6
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• pp.16-25
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• 2007

In a companion paper, a rational mechanical model to predict the entire behavior of point-loaded RC slender beams (a/d > 2.5) without shear reinforcement was developed. This paper presents the test results of 9 slender shear beams and compares them with analytical results performed by the proposed model. They are grouped by two parameters, which are shear span ratio and concrete strength. Three kinds of concrete strength the 26.5, 39.2, and 58.8 MPa were included as a major experimental parameter together with different shear span ratios ranging from 3 to 6 depending on the test series. Tests were set up as a traditional 3 point bending test. Various measurements were taken to monitor abrupt shear failure. Test results were not only compared with analytical results from the proposed model, but also other formulas, to consider the various aspects of shear failure such as kinematical conditions or shear capacity. Finally, a review of the proposed model is presented with respect to the shear transfer mechanisms and the effect of test parameters. Results show that several assumptions and proposals adopted in the proposed model are rational and reasonable.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.2 s.48
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• pp.1-10
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• 2006

Reinforced concrete bridge columns with relatively small aspect ratio show flexure-shear behavior, which is flexural behavior at initial and medium displacement stages and shear failure at final stage. Since the columns with flexure-shear failure have lower ductility than those with flexural failure, shear capacity curve models shall be applied as well as flexural capacity curve in order to determine ultimate displacement for seismic design or performance evaluation. In this paper, a modified shear capacity curve model is proposed and compared with the other models such as the CALTRANS model, Aschheim et al.'s model, and Priestley et al.'s model. Four shear capacity curve models are applied to the 4 full scale circular bridge column test results and the accuracy of each model is discussed. It may not be fully adequate to drive a final decision from the application to the limited number of test results, however the proposed model provides the better prediction of failure mode and ultimate displacement than the other models for the selected column test results.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.75-78
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• 2008

Limit states of a tension member are the yielding of gross section, fracture of net section, and block shear failure. Block shear failure is very complicated than other limit state because of interaction of tension and shear failure. Block shear failure is studied continuously since the 1970s. However, failure model to estimate the strength of block shear failure provided in current design specifications is not reflective of the failure mode observed in the various experimental studies. Comparisons between the experimental results and design rules in various specifications about the block shear failure were conducted in this study. Also, the need for further studies of block shear failure were proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.391-394
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• 2005

A theoretical model was developed to predict the shear strength of slender reinforced concrete beams. The shear force applied to a cross-section of the beam was assumed to be resisted primarily by the compressive zone of intact concrete rather than by the tensile zone. The shear capacity of the cross section was defined based on the material failure criteria of concrete: failure controlled by compression and failure controlled by tension. In the evaluation of the shear capacity, interaction with the normal stresses developed by the flexural moment in the cross section was considered. In the proposed strength model, the shear strength of the beam and the location of the critical section were determined at the intersection between the shear capacity and shear demand curves. The proposed strength model was verified by the comparisons to prior experimental results.