• The Journal of Engineering Geology
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• v.19 no.2
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• pp.177-189
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• 2009

The shear strength has been managed as an important factor in soil mechanics. The shear strength estimation model was developed to evaluate the shear strength using only a few soil properties by the linear regression analysis model which is one of the statistical methods. The shear strength is divided into two part; one is the internal friction angle (${\phi}$) and the other is the cohesion (c). Therefore, some valid soil factors among the results of soil tests are selected through the correlation analysis using SPSS and then the model are formulated by the linear regression analysis based on the relationship between factors. Also, the developed model is compared with the result of direct shear test to prove the rationality of model. As the results of analysis about relationship between soil properties and shear strength, the internal friction angle is highly influenced by the void ratio and the dry unit weight and the cohesion is mainly influenced by the void ratio, the dry unit weight and the plastic index. Meanwhile, the shear strength estimated by the developed model is similar with that of the direct shear test. Therefore, the developed model may be used to estimate the shear strength of soils in the same condition of study area.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.6
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• pp.1-9
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• 2009

This study carried out a shear experiment on concrete deep beam reinforced AFRP to investigate the shear strength of deep beam. The test was conducted on 8 specimens, and the variables were shear span ratio, reinforcement ratio, effective depth, and rebar type. We compared shear strength using ACI 318-08 STM with proposed equations that considered arching action according to shear span ratio. As a result, it was found that shear strength of deep beam reinforced AFRP rebar presented higher shear strength than steel rebar. ACI STM's predictions are more accurate than other predicting equations, and thus this research proposed model versus effective compressive strength of the concrete strut that considered strut size effect based on test results. The predictions obtained using the proposed model are in better agreement than previous equations and codes.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.51-58
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• 2008

This study is to investigate the ultimate shear load of prestressed girder made of Ultra High Performance Fiber Reinforced Concrete (UHPFRC). Nine girders were tested until failure in shear. An analytical model to predict the ultimate shear load was formulated based on the Two Bounds Theory. A fiber reinforcing model was constituted based on the random assumption of steel fiber uniform distribution. The predicted values were compared with the conventional predictions and the test results. The proposed equations for computing the ultimate shear strength can be used for the ultimate failure status analysis, which could also be utilized for numerical limit analysis of prestressed UHPFRC girder. The established fiber reinforcing theoretical model can also be a reference for micro-mechanics analysis of UHPFRC.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.445-448
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• 2010

본 연구는 섬유 보강 폴리머(Fiber Reinforced Polymers, 이하 FRP) bar로 보강된 콘크리트 깊은 보의 전단강도를 평가하기 위하여 전단경간비, 보강비, 주근의 종류를 변수로 총 6개의 실험체에 대한 전단 실험을 수행하였다. 전단실험을 토대로 FRP bar로 보강된 콘크리트 깊은보의 균열 및 처짐에 대한 거동 조사를 수행하였으며, ACI 318-08의 스트럿-타이 모델을 이용한 전단강도와 아치작용을 고려한 기존 제안식에 의한 전단강도를 비교 평가하였다. 그 결과, FRP bar로 보강한 실험체와 철근으로 보강한 실험체는 상이한 전단거동을 보였으며, FRP bar로 보강한 경우의 전단강도가 철근으로 보강한 경우보다 증가하는 것으로 나타났다. 전단강도 산정에 있어서는 ACI 318-08의 스트럿-타이 모델을 이용한 방법이 기존 제안식에 의한 방법보다 상대적으로 정확했다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.1-8
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• 2020

This study presents a shear strength estimation model, in which the shear failure of a reinforced concrete (RC) member is assumed to be governed by the flexure-shear mechanism. Two shear demand curves and corresponding potential capacity curves for cracked tension and uncracked compression zones are derived, for which the bond mechanism developed between reinforcing bars and surrounding concrete is considered in flexural analysis. The shear crack concentration factor is also addressed to consider the so-called size effect induced in large RC members. In addition,unlike exising methods, a new formulation was addressed to consider the interaction between the shear contributions of concrete and stirrup. To verify the proposed method, an extensive shear database was established, and it appeared that the proposed method can capture the shear strengths of the collected test specimens regardless of their material properties, geometrical features, presence of stirrups, and bond characteristics.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.60-67
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• 2020

Recently, many studies have been conducted on the structural behavior of HPFRCC, but most of the studies focused on the flexural behavior while studies on the shear behavior are limited. In this study, a model has been developed to reasonably predict the shear strength of a HPFRCC beam without stirrups. To develop the model, a HPFRCC beam was simply idealized with upper & lower chords resisting bending moment and a web shear element resisting shear forces. Then, taking into the account of the tensile behavior of HPFRCC, the main diagonal compressive strut angle and shear stress of the web shear element were evaluated on shear failure. Then, the shear strength of the HPFRCC beam could be evaluated. For the verification of the proposed model, the predictions by the proposed model were compared with the test results of 48 HPFRCC beams exhibiting shear failure. The results showed that the proposed model reasonably predicted the actual shear strength with an average of 1.045 and CoV of 0.125. This study are expected to be useful for related researches and design of members or structures to which HPFRCC is applied.

• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.185-193
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• 2011

In the present study, a unified shear design method was developed to evaluate the shear strength of concrete beams with and without FRP shear reinforcement. The contributions of FRP and concrete on shear strength were defined separately. By comparing the current design method calculated results with the existing test results, it was found that Triantafillou model shows a reliable prediction of FRP effective strain and FRP shear strength contributions. The concrete shear strength contribution was defined by the strain-based shear strength model developed in the previous study. The shear strength of concrete compression zone was evaluated based on the material failure criteria of the concrete subjected to the compressive normal and shear stresses. The proposed strength model was verified by comparing its prediction results to prior test results. The comparisons showed that the proposed method accurately predicts the strengths of the test specimens for both FRP shear reinforced and unreinforced concrete beams.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.982-988
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• 2002

Current design equations for shear strength of reinforced concrete columns generally overestimate the shear strength contribution by the circular transverse reinforcement. This is due to the simplification of the discrete distribution of the reinforcement to the continuous one and the imprudent application of the classical truss model to the circular section, which is different in shear-resisting mechanism from the rectangular section. This study presents a rational model for the prediction of shear strength contribution by the circular transverse reinforcement considering the starting location of a diagonal crack, the number of transverse reinforcing bars crossing the main crack and the geometrical strength component of the transverse resistance. It was found that, for lower amount transverse reinforcement, the crack starting point and the number of crack crossing bars greatly influence the shear-resisting capacity. Proposed model leads to a reliable design equation which is derived using a linear regression method and is in good agreement with the lower bound of exact strength curve.

• Journal of the Korean Geosynthetics Society
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• v.21 no.2
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• pp.21-30
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• 2022

Shear strength is the most important indicator in the evaluation of rock slope stability. It is generally estimated by comparing the results of existing literature data, back analysis, experiments and etc. There are additional variables related to the state of discontinuity to consider in the shear strength of the rock slope. It is difficult to determine whether these variables exist through drilling, and it is also difficult to find an exact relationship with shear strength. In this study, the data calculated through back analysis were used. The relationship between previously considered variables was applied to deep learning and the possibility for estimating shear strength of rock slope was explored. For comparison, an existing simple linear regression model and a deep learning algorithm, a deep neural network(DNN) model, were used. Although each analysis model derived similar prediction results, the explanatory power of DNN was improved with a small differences.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.233-240
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• 1998

A rational expression, developed to predict the shear strength of reinforced concrete beams, is derived from the relationship between shear and the rate of change of bending moment along a beam coupled with experimental findings for the arch action. The proposed ultimate shear strength equation, arising from analytical premises and then calibrated with experimental data, is a similar form to the ACI 318 equation derived mainly from empirical approach. The proposed equation depends on the concrete compressive strength, amount of longitudinal steel content, and the shear span-to-depth ratio, and rationally reflects the shear resistance mechanism of combined beam action and arch action in reinforced concrete beams. The proposed equation applied to existing test data and the results were compared with those predicted by the ACI 318 equation and the Zsutty's equation.