Journal of the Korea institute for structural maintenance and inspection (한국구조물진단유지관리공학회 논문집)

Korea Institute for Structural Maintenance Inspection (한국구조물진단유지관리공학회)
권호 표지
DOI QR코드

DOI QR Code

Estimation of Nondestructive Strength Equations Based on the Results of In-situ Concrete Strength for Existing Bridges

국내 교량의 현장 코어강도를 활용한 개선된 비파괴강도 추정식 제안

  • 김훈겸 (서울특별시청 도로시설과)
  • Received : 2017.11.14
  • Accepted : 2018.02.28
  • Published : 2018.03.01
Download PDF
⟨ Previous Next ⟩

Abstract

Nondestructive strength Equations are commonly used to determine the strength of concrete. However, the application of the existing equations may include many errors because this method is proposed on the basis of limited experimental parameters while actual bridges have various parameters such as conditions of concrete mixtures, properties of concrete strength, etc. Also, the error among the existing equations causes the confusion when engineers select the proper estimation equation for the concerned bridge. 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. According to results of analyses, the nondestructive strength equation proposed by CNDT Committee of Architectural Institute of Japan had high relationship with core strength. However, the strengths predicted by this equation, are underestimated when concrete's strengths are over 30 MPa, otherwise, they are overestimated. Also in this paper, based on the relationship between the estimated nondestructive concrete strengths and the core specimen strengths the modified strength equation through simple correlation analysis is proposed.

콘크리트 비파괴강도 추정식은 일반적으로 콘크리트 강도를 결정하는데 사용된다. 그러나 기존의 추정식들은 대부분 제한된 실험 변수를 토대로 제안되어 배합조건, 강도특성 등이 다양한 실제 공용중 교량의콘크리트 압축강도 추정시 많은 오류를 포함한다. 본 연구에서는 297개 공용 교량의 정밀안전진단 결과 중 콘크리트 비파괴시험 및 현장 코어강도 시험결과를 토대로 콘크리트 부재의 코어강도와 비파괴 추정강도 평가결과를 비교분석하였다. 분석결과 분석이 이루어진 기존 추정식들 중 일본건축학회 CNDT소위원회 강도계산식이 다른 추정식에 비하여 실제파괴강도와의 오차가 가장적고 상관분석의 신뢰도도 가장높은 것으로 검토되었다. 그러나 이 추정식은 코어강도가 30 MPa이상일때 추정강도는 과소평가되는 것으로 나타났다. 이에 본 논문에서는 추정식에 의한 강도와 현장 코어강도사이의 관계를 활용하여 회귀분석을 통한 개선된 비파괴강도 추정식을 제안하였다.

Keywords

References

  1. Kim, G. H. (2007), The Reliability for the Estimated Strength by the Ultrasonic Pulse Velocity, Hanyang University, Seoul, 31-43.
  2. Kim, H. K. and Kim, S. B. (2010), Service Life Prediction and Carbonation of Bridge Structures According to the Environmental Conditions, Journal of KSMI, 14(4), 126-32.
  3. Kim, M. W., Oh, H. S., and Oh, K. C. (2016), Estimating the Compressive Strength of High-strength Concrete Using Surface Rebound Value and Ultrasonic Velocity, Journal of KSMI, 20(2), 1-9.
  4. KISTEC (2011), Guideline of Precise Inspection for Safety and Diagnosis, Common, 12-56.
  5. Kwon, Y. -W., Park S. -C., and Kim M. -S. (2006), Strength Prediction Equations for High Strength Concrete by Schmidt Hammer Test, Journal of the Korea Concrete Institute, 18(3), 389-395. https://doi.org/10.4334/JKCI.2006.18.3.389
  6. Lim, S. Y. (2007), A Study on the Estimation of Compressive Strength of Concrete by Non-Destructive Test, Daegu University, Daegu, 1-2.
  7. Oh, H. S., and Oh, K. C. (2016), An Empirical Estimation Procedure of Concrete Compressive Strength Based on the In-Situ Nondestructive Tests Result of the Existing Bridges, Journal of KSMI, 20(4), 111-119.
  8. RILEM CNDT-Committee (1980), RILEM Tentative Recommendations for In-situ Concrete Strength Determination by Non-Destructive Combined Methods(First draft), May, 1980.
  9. RILEM (1994), RILEM Technical Recommendations for the Testing and Use of Construction Materials, E & FN SPON.