• Smart Structures and Systems
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• v.3 no.1
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• pp.51-68
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• 2007

High-strength concrete (HSC) is becoming increasingly attractive for various construction projects since it offers a multitude of benefits over normal-strength concrete (NSC). Unfortunately, current design provisions for shear capacity of RC slender beams are generally based on data developed for NSC members having a compressive strength of up to 50 MPa, with limited recommendations on the use of HSC. The failure of HSC beams is noticeably different than that of NSC beams since the transition zone between the cement paste and aggregates is much denser in HSC. Thus, unlike NSC beams in which micro-cracks propagate around aggregates, providing significant aggregate interlock, micro-cracks in HSC are trans-granular, resulting in relatively smoother fracture surfaces, thereby inhibiting aggregate interlock as a shear transfer mechanism and reducing the influence of compressive strength on the ultimate shear strength of HSC beams. In this study, a new approach based on genetic algorithms (GAs) was used to predict the shear capacity of both NSC and HSC slender beams without shear reinforcement. Shear capacity predictions of the GA model were compared to calculations of four other commonly used methods: the ACI method, CSA method, Eurocode-2, and Zsutty's equation. A parametric study was conducted to evaluate the ability of the GA model to capture the effect of basic shear design parameters on the behaviour of reinforced concrete (RC) beams under shear loading. The parameters investigated include compressivestrength, amount of longitudinal reinforcement, and beam's depth. It was found that the GA model provided more accurate evaluation of shear capacity compared to that of the other common methods and better captured the influence of the significant shear design parameters. Therefore, the GA model offers an attractive user-friendly alternative to conventional shear design methods.

• Journal of the Korea Concrete Institute
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• v.21 no.1
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• pp.75-84
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• 2009

An analytical model for predicting the shear strength of prestressed concrete beams without shear reinforcement was developed, on the basis of the existing strain-based shear strength model. It was assumed that the compression zone of intact concrete in the cross-section primarily resisted the shear forces rather than the tension zone. The shear capacity of concrete was defined based on the material failure criteria of concrete. The shear capacity of the compression zone was evaluated along the inclined failure surface, considering the interaction with the compressive normal stress. Since the distribution of the normal stress varies with the flexural deformation of the beam, the shear capacity was defined as a function of the flexural deformation. The shear strength of a beam was determined at the intersection of the shear capacity curve and the shear demand curve. The result of the comparisons to existing test results showed that the proposed model accurately predicted the shear strength of the test specimens.

• Journal of Korean Association for Spatial Structures
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• v.3 no.1 s.7
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• pp.77-85
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• 2003

This paper presents a truss model that can predict the shear behavior of reinforced concrete (RC) beams subjected to the combined actions of shear and flexure. Unlike other truss models, the proposed truss model, TATM, takes into account the effect of the flexural moment on the shear strength of RC beams with different shear span-to-depth ratios. To check the successfulness of the proposed model experimentally obtained stress shear strain curves were compared to the predicted ones using the proposed truss model. Furthermore, the shear strengths of 170 RC test beams with variable shear span-to-depth ratios were compared to the shear strengths as given by the truss model reported in this paper.

• Smart Structures and Systems
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• v.14 no.5
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• pp.785-809
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• 2014

In this paper, an Adaptive nerou-based inference system (ANFIS) is being used for the prediction of shear strength of high strength concrete (HSC) beams without stirrups. The input parameters comprise of tensile reinforcement ratio, concrete compressive strength and shear span to depth ratio. Additionally, 122 experimental datasets were extracted from the literature review on the HSC beams with some comparable cross sectional dimensions and loading conditions. A comparative analysis has been carried out on the predicted shear strength of HSC beams without stirrups via the ANFIS method with those from the CEB-FIP Model Code (1990), AASHTO LRFD 1994 and CSA A23.3 - 94 codes of design. The shear strength prediction with ANFIS is discovered to be superior to CEB-FIP Model Code (1990), AASHTO LRFD 1994 and CSA A23.3 - 94. The predictions obtained from the ANFIS are harmonious with the test results not accounting for the shear span to depth ratio, tensile reinforcement ratio and concrete compressive strength; the data of the average, variance, correlation coefficient and coefficient of variation (CV) of the ratio between the shear strength predicted using the ANFIS method and the real shear strength are 0.995, 0.014, 0.969 and 11.97%, respectively. Taking a look at the CV index, the shear strength prediction shows better in nonlinear iterations such as the ANFIS for shear strength prediction of HSC beams without stirrups.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.27-38
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• 2003

The characteristics and prediction model of the shear strength of unsaturated residual granite soils were studied in this paper. In order to investigate the influence of the net normal stress on the shear strength, unsaturated triaxial tests and SWCC tests were carried out by varying the net normal stress. Experimental data for unsaturated shear strength tests were compared with predicted shear strength envelopes obtained from existing prediction models. It was shown that the soil-water characteristic curve and the shear strength of the unsaturated soil varied with the change of the net normal stress. Therefore, to achieve a truly descriptive shear strength envelope for unsaturated soils, the effect of the normal stress on the contribution of matric suction to the shear strength has to be taken into consideration. In this paper, a modified prediction model f3r the unsaturated shear strength was proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.591-596
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• 1999

Current design methods as well as the majority of the previous researches for shear strength of the reinforced concrete are based on empirical method. There is a need to propose the rational models based on analytical approach. This paper presents the modified strut-and-tie model for reinforced concrete columns, under axial compression, shear, and flexural moment, considering tensile strength of concrete. Using this model, the strength and the failure mode of R/C columns are investigated, and the proposed models are compared with test data available in the literature.

• Journal of the Korean Geotechnical Society
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• v.39 no.5
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• pp.5-12
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• 2023

This study investigates the existing models for estimating the shear strength of rock joints, presents related problems, and introduces a newly proposed model to overcome the problems. The results of many experimental tests show that the shear strength of a rock joint depends on many complex factors, including asperity angle, compressive strength, applied normal stress, friction angle, asperity cohesive strength, and progressive damage of asperities. However, the existing models do not account for these factors enough. To overcome these problems, Son (2020) developed a new model to estimate the shear strength of rock joints and confirmed its reliability by comparing with experimental results and existing models. In this paper, the developed model was used to investigate the various factors that affect the joint shear strength, and the results were compared and analyzed. Through this study, the factors that affect the shear strength of the rock joint could be identified in more detail.

• Journal of Korean Society of Steel Construction
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• v.18 no.1
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• pp.71-80
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• 2006

The behaviors of steel-plate shear panels were investigated through an experimental and analytical study, using mild steel (S40). Steel-plate shear panels buckle at small loads, and their strength is based on the shear panel's postbuckling strength due to tension field action. In design practice, however, the capacity of steel-plate shear panels is limited to the elastic buckling strength of shear panels. Th e National Standard on Limit States Design of Steel Structures, CAN/CSA-S16.1-94 (1994) contains a guideline for the analysis of thi n, unstiffened, steel-plate shear walls using the strip model. In this paper, the structural capacity of shear panels was evaluated using the results of the experiment and of the strip model analysis.

• Computers and Concrete
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• v.10 no.3
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• pp.259-276
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• 2012

A total of nine reinforced concrete corbels were tested, in this study. Six were externally strengthened with carbon fiber reinforced plastics (CFRP), in the horizontal direction. The cross-sectional area of CFRP and the shear span-to-effective depth ratios are the parameters considered, in this study. Test results indicate that the higher the cross-sectional area of CFRP, the higher is the shear strength of the corbels, and the lower the shear span-to-effective depth ratios, the higher is the shear strength of corbels. The shear strength predicted by the design provisions in section 11.8 of the ACI Code, the strut-and-tie model in Appendix A of the ACI Code, and the softened strut-and-tie (SST) model were compared with the test results. The comparisons show that both the strut-and-tie model in Appendix A of the ACI Code, and the SST model can accurately predict the shear strength of reinforced concrete corbels, strengthened with CFRP.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.577-582
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• 2000

This study is aimed to evaluate the shear strength of reinforced concrete deep beams subject to concentrated loads, using a simplified strut-tie model. For the shear strength prediction of deep beams, it is prerequisite to evaluate the effective width of strut and to verify the efficiency factors proposed by MacGregor et al.. The results analyzed by truss models have been compared with those calculated by domestic code for the existing data of 90 deep beam specimens. The shear strength of deep beams were reviewed with respect to concrete strength, the shear span-depth ratio, and the ratio of web reinforcements. The results showed that the shear strength of the proposed model gave a better agreement than the domestic code approach.