This study aims to propose a simplified equation for estimating the bond strength of corroded reinforcing bars. To this end, extensive parametric analyses were performed using the detailed analysis method presented in the authors’ previous study, where a wide range of critical variables were considered, such as compressive strength of concrete, net cover thickness, and reinforcing bar diameter. The sensitivity in bond strength of the corroded reinforcing bar according to each variable was evaluated. On this basis, a simplified formula for the bond strength of the corroded reinforcing bar was derived through regression analysis. The proposed equation was rigorously tested and verified using the bond test results of corroded reinforcing bars collected from the literature. The results confirmed that the proposed equation could estimate the bond strengths of specimens with better accuracy than the existing models, providing a reliable tool for engineers and researchers. In addition, the proposed equation was used to analyze the development length required for corroded tensile reinforcement to exert its yield strength, and it showed that the cover thickness of concrete must be at least four times the diameter of the reinforcing bar to achieve the yielding strength of reinforcing bar even at a corrosion degree of more than 5.0%.

한국시설안전공단에서는 ‘시설물의 안전관리에 관한 특별법’에 따라 철근콘크리트 구조물의 안전점검 및 정밀안전진단을 실시하도록 제시하고 있다. 그러나 한국시설안전공단 안전점검 및 정밀안전진단 세부지침의 평가방법에서는 평가결과를 등급으로 제시하기 때문에 구조물의 잔존수명을 알 수 없으며 부등침하가 구조물의 잔존수명에 미치는 영향을 반영하지 못한다. 따라서, 이 연구에서는 부등침하의 영향이 반영된 구조물의 잔존수명 평가모델을 제시하고자 하였다. 부등침하와 각 변위의 상관관계를 나타내는 기존의 연구를 바탕으로 부재의 공칭강도에 부등침하의 영향을 반영시키기 위한 식을 제시하였으며, 실제 철근콘크리트 구조물의 현장데이터를 활용하여 부등침하가 구조물의 잔존수명에 미치는 영향을 분석하였다.

포스트텐션 프리캐스트콘크리트(Precast Concrete, PC) 보-기둥 접합부에서는 프리스트레스가 도입된 긴장재가 접합부 내부를 관통하기 때문에, 기존의 철근콘크리트(Reinforced Concrete, RC) 보-기둥 접합부와 다른 거동을 나타내며, 포스트텐션 PC 접합부의 정확한 해석 및 설계를 위해서는 먼저 긴장재의 부착특성 및 그에 따른 접합부 거동이 명확히 규명 되어야 한다. 이 연구에서는 포스트텐션 PC 보-기둥 접합부에서 긴장재의 부착특성을 분석하고, 그에 따른 보의 거동 및 파괴모드를 규명함으로써 이를 추후 보-기둥 접합부 모델링에 활용하고자 한다.

이 연구에서는 전단연결재의 종류를 변수로 더블리브유닛 깊은 데크플레이트 슬래브의 휨 실험을 수행하였으며, 실험결과를 기반으로 비선형유한요소해석을 통하여 춤이 깊은 데크플레이트와 콘크리트 사이의 합성도를 평가하였다. 그 결과, 전단 연결재가 설치되어 있는 경우 휨 강성 및 강도가 크게 향상되는 것으로 나타났다.

In this study, a numerical research has been conducted to investigate the fire resistance performance of prestressed hollow-core slabs, in which the number of prestressing strands and the load ratio were set as the analysis parameters. Based on the numerical simulation results, the temperature distribution and deflection according to the fire duration time were analyzed in detail.

In a pretensioned concrete member, the effective prestress is not fully developed in a certain length from the end of the member, which is defined as transfer length. Because of its complex mechanism, previous transfer length models are mostly empirical and provide very different results. In this study, the Adaptive Neuro-Fuzzy Inference System(ANFIS) was introduced to estimate the transfer lengths of pretensioned concrete members. A total of 209 experimental data has been used to train ANFIS, and the trained ANFIS algorithm estimated the transfer lengths of test specimens very accurately.

In this study, the flexural tests were performed to investigate the flexural performance of prestressed hybrid wide flange (PHWF) beams. The main test variable was the shear stud on the top steel flange for composite action with the topping slab. All the specimens had the flexural strengths exceeding their design strengths. The test results also indicate that the PHWF beams had experienced fully composite behavior with high ductility, regardless of the existence of shear studs.

The volume expansion of corroded steel reinforcement produces tensile stress on the surrounding concrete, which causes splitting cracking of concrete cover, and deteriorates the service ability and durability of reinforced concrete(RC) members. In addition, since the steel corrosion induces bond strength degradation between steel bar and concrete, the structural performance of RC members can be deteriorated significantly. In this study, the theoretical study was performed to probe the mechanism of the bond strength reduction due to steel corrosion. The bond strength between corroded steel bar and concrete was calculated by mathematically formulating the expansion pressure of corroded steel reinforcement. The proposed model was verified by comparing with the existing test results, and it showed that the proposed model estimate the bond strength reduction of corroded RC elements very closely.