• 한국도로학회논문집
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• 제20권3호
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• pp.39-46
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• 2018

PURPOSES: This study is to estimate nondestructive strength equation based on probability for bridges using field test data. METHODS : In this study, a series of the field inspection and the test have been performed on 297 existing bridges, in order to evaluate the bridges, based on the test results of the in-depth inspection, and the estimated strengths by means of the nondestructive strength equations are analyzed and compared with results of the core specimen strengths. RESULTS : According to results of analyses, In case of standard design compressive strength of concrete is 18MPa, 21MPa, similar reliability of RILEM equation were 0.89~0.90, but in case of standard design compressive strength of concrete is 35MPa, 40MPa were 0.4~0.56. According to standard design compressive strength of concrete is 40MPa, similar reliability of ultrasonic pulse velocity method equation were 0.56. CONCLUSIONS :RILEM equation had high similar reliability than other equation in case of standard design compressive strength of concrete is 18MPa, 21MPa, but had low similar reliability than other equation in case of standard design compressive strength of concrete is 35MPa, 40MPa. and ultrasonic pulse velocity method equation had low similar reliability than other equation in case of standard design compressive strength of concrete is 40MPa.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.253-258
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• 2000

The purpose of this paper is to propose the deduction equation of shear strength of high strength reinforced concrete beams input steel fibrous. To propose the deduction equation of shear strength, we studied high reasonable verification by comparing proposal equation with other researches such as equation of ACI code 318-95 or equation of Zsutty. To propose the deduction equation of shear strength, regression analysis was done using MINITAP program. Finally, it has been tried to make an improvement of brittleness quality of high strength concrete which has been weak points and it is convinced the result by increase of deflection and strain about loads.

• 한국구조물진단유지관리공학회 논문집
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• 제3권1호
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• pp.129-136
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• 1999

In this paper, the new non-destructive equation will be proposed and evaluated in comparison to the other foreign's non-destructive equation. Through the comparisons cores strength of mock structure with compressive strength obtained from new non-destructive equation ; rebound hammer, ultra-sonic pulse velocity and combined method, it will be analyzed about application of non-destructive equation. The results are following. The new non-destructive equations follow ; (1) $F_c=9.5R{\cdot}N+62.5$ (2) $F_c=243Vp-739$ (3) $F_c=8.1R_o+205.3V_p-802$ where, $F_c$ : Compressive Strength, $R_o$ : Rebound Number. $V_p$ : Ultra-Sonic Pulse Velocity Trough the result of mock structure test, the combined method is superior to rebound method and ultra-sonic pulse velocity method in the estimation of concrete strength. In order to apply the non-destructive equation of concrete strength to the structures, it is necessary that we should be made process study on the non-destructive equation for estimation of concrete strength in the range, time and strength of application under long-term.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.878-883
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• 2003

To modify some problems of ACI shear provisions, ultimate shear strength equation considering size effect and arch action to compute shear strength in high-strength concrete beams without stirrups is presented in this research. Three basic equations, namely size reduction factor, rho factor, and arch action factor, are derived from crack band model of fracture mechanics, analysis of previous some shear equations for longitudinal reinforcement ratio, and concrete strut described as linear function in deep beams. Constants of basic equations are determined using statistical analysis of previous shear testing data. To verify proposed shear equation for each variable, namely d, , ρ, f/sub c/' and aid, about 250 experimental data are used and proposed shear equation is compared with ACI 318-99 code, CEB-FIP Model code, Kim & Park's equation and Zsutty's equation. While proposed shear equation is simpler than other shear equations, it is shown to be economical predictions and reasonable safety margin. Hence proposed shear strength equation is expected to be applied to practice shear design.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.695-700
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• 2001

The objective of this study is to evaluate the flexure strength of steel fiber reinforced concrete beams and the effect of the adding steel fiber to flexural strength, and is to compare the proposed equation with the previous equation for predicting the flexural strength of fiber reinforced concrete beams. Based on earlier published studies and tests, predictive equation is proposed for evaluating the flexural strength of steel fiber reinforced concrete beams. The proposed equation gave good prediction for the flexural strength of the tested beams.

• 한국건축시공학회지
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• 제2권3호
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• pp.123-130
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• 2002

Recently, it is being studied on the high strength concrete in many laboratories and being applied to the construction field actually. But non-destruction testing equation that to be proposed about normal strength concrete in Japan has been using because the systematic study results for the estimation of compressive strength of high strength concrete do nit exist. So it is essential to suggest the non-destruction testing equation for the estimation of compressive strength of high strength concrete. This is an experimental study to analyze and investigate the non-destruction testing equation for the estimation of compressive strength of high strength concrete. The results are as follows; The relation between rebound number, pulse velocity and compressive strength of high strength concrete have lower coefficient than combined method of rebound number and pulse velocity. Also new non-destructive testing equation for the estimation on the compressive strength of high strength concrete was suggested in this study, and it is considered that these equations have possibility to be applied in domestic construction field.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 가을 학술발표회 논문집
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• pp.155-160
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• 1992

In this study , the size effect on diagonal shear failure of reinforced high strength concrete beams was investigated, For this purpose, ten singly reinforced high strength concrete beams without web reinforcement were tested for five different dimensions of effective depth which were varied from 67mm to 915mm. The compressive strength of concrete used in this study was 53.7 MPa. One type of reinforcing bar with nominal yield strength of 400 MPa was used. Test results were analyzed and compared with strength predicted by ACI code equation, Zutty's equation and Bazant &Kim's equation. As the results, ACI code equation was seriously unconservative for beams with d of 915mm. Bazant & Kim's equation predicted well the trend of test data. Within the scope of this study, there was no clear difference in size effect with variation of compressive strength of concrete.

• 한국강구조학회 논문집
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• 제13권2호
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• pp.177-189
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• 2001

현대 건축물들의 고층화 추세에 따라 등장한 구조물의 공사비 절감을 위한 한 방법으로 H형강보의 웨브 부분에 설비용 덕트와 배관류 등을 관통시키기 위하여 개구부를 두는 유공보를 자주 사용하고 있다. 본 연구에서는 현재 유공보의 설계에 사용되고 있는 기존의 강도식들의 문제점을 살펴보고 소성 붕괴 매커니즘에 기초를 둔 보다 합리적인 강도식을 제안하고자 한다. 제안식은 기존의 강도식들과 비교하여 볼 때 단순하며 이해하기 쉽다. 제안식의 검증은 과거에 이루어진 연구 결과들을 사용하여 평가되어 졌다. 이들 연구결과들을 근거로 제안식의 극한 강도를 비교해 볼 때 현재 실무에서 사용되어 지고있는 강도식들보다 합리적인 결과 값을 기대할 수 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.475-480
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• 2001

In this study, a empirical equation which can be feasibly used to evaluate minimal track buckling strength without exact numerical analysis is presented. Parameter studies we carried out to investigate the effects of the individual factor on buckling strength. In order to simulate track buckling in the field as precisely as possible, a rigorous buckling model which accounts for all the important parameters is adopted. A empirical equation for prediction of minimal track buckling strength is derived by taking nonlinear regression of data which are obtained from numerical analyses. Its characteristics and applicability are investigated by comparing the results by the presented equation with the one by the equation which was presented in japan, and is frequently using in korea when designing track structure.

• International Journal of Concrete Structures and Materials
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• 제18권1E호
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• pp.43-48
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• 2006

This paper presents an elastic modulus equation more appropriate for predicting the elastic modulus of structural materials designed for and made of high- and ultra high-strength concrete under current domestic situation in Korea. In order to validate and assess the proposed elastic modulus equation, more than 400 laboratory test data available in the domestic literature on compressive strength of concrete in the range between 400 to 1,000 $kgf/cm^2$ were used and analyzed statistically. Comparison analyses of the proposed elastic modulus equation with previously suggested equations of ACI363R, CEB-FIP, NS3473 and New-RC are also presented to demonstrate its applicability in domestic practice.