20d_b 정착길이를 가지는 SD700 갈고리철근과 확대머리철근의 정착성능 실험

Anchorage performance tests of SD700 hooked bar and headed bar with a anchorage length of 20d_b

Abstract

With the increase of the skyscraper center, the development of large-diameter and high-strength reinforcing bars is being carried out to solve the dense reinforcement. In case of the steel reinforced concrete with a small cross section such as beam-column joints, the development length becomes short when straight bars are used. Therefore, it is possible to solve the problem that the development length becomes short by using the bearing strength of the hooked bar and headed bar. In this study, the exterior beam-column joint test of SD700 hooked bar and headed bar with anchorage length of 20db was conducted to extend the development length limitation of hooked bar and headed bar. As a result of the evaluation of the anchorage strength using the design equation by KCI, the average of the [measured value]/[predicted value] ratio was 1.31 for the hooked reinforcing bars. In the case of headed bars, the average of the [measured value]/[predicted value] ratio was 1.12. In addition, in order to compare the anchorage performance of the hooked bar and the headed bar, the measured values were divided by the square root of the compressive strength of the concrete to compare the anchorage strength. Under the same conditions, the anchorage strength of headed bars was 8.5% higher than the hooked bars.

Figure 1. Marques and Jirsa(1975)의 갈고리철근 외부 보-기둥 접합부 실험

Figure 2. Chun et al.(2017)의 확대머리철근 외부 보-기둥 접합부 실험

Figure 3. 실험 가력도

Figure 4. 실험체 상세

Figure 5. SD700 철근인장시험 stress-strain 곡선

Figure 6. 측면파열파괴양상

Figure 7. 콘크리트구조기준에 따른 예측값에 대한 실험값

Figure 7. 갈고리철근과 확대머리철근의 정착강도 비교

Table 1. 실험체 목록

Table 2. 콘크리트 재료시험 결과

Table 3. 철근인장강도시험 결과

Table 4. 외부 보-기둥 접합부 정착강도 실험결과