Prestressing Effect of LNG Storage Tank with 2,400 MPa High-Strength Strands

Abstract

High-strength strands have been increasingly applied to recent actual structures in Korea. Structural effect of the increased spacing of sheaths was investigated in this study when the usual 1,860 MPa strands of an LNG storage tank are replaced with 2,400 MPa high-strength strands. First, finite element models of a cylindrical wall of an LNG tank were established and prestressing effect of the circumferential and vertical tendons was considered as equivalent loads. As a result of varying the tendon spacing and prestressing force with the total prestressing effect kept the same, the stress distribution required in design was obtained with the high-strength strands. Also, a full-scale specimen that corresponds to a part of an LNG tank wall was fabricated with 31 high-strength strands with 15.2 mm diameter inserted in each of two sheaths. It was observed that such a high level of prestressing force can be properly transferred to concrete. Moreover, an LNG tank with the world's largest 270,000 kl capacity was modeled and the prestressing effect of high-strength strands was compared with that of normal strands. The watertightness specifications such as residual compressive stress and residual compression zone were also ensured in case of leakage accident. The results of this study can be effectively used when the 2,400 MPa high-strength strands are applied to actual LNG tanks.

An Improved Equation for Predicting Compressive Stress in Posttensioned Anchorage Zone

“…In order to validate the accuracy of the proposed equation, the stress distributions, which were obtained by the original equation (1) of AASHTO and the improved AASHTO formula of equations (6a) and (6b) proposed in this study, were compared with that measured in the test of a posttensioned full-scale specimen [21,22]. Figure 12 shows the specimen with the length, width, and thickness of 7 m, 4 m, and 0.75 m, respectively.…”

Static and Cryogenic Performance Evaluation of 2400 MPa PT Anchorage System for Applying LNG Storage Tank

“…프리스트레스트 콘크리트(Pre-Stressed Concrete, PSC) 공 법 중에 하나인 포스트텐션(Post-Tension, PT) 공법은 굳은 콘크리트 내에 매립된 쉬스관에 여러 다발의 강연선을 삽입하 고 동시에 여러 강연선 다발을 긴장한 후 이를 하나의 정착장치 에 정착하여 콘크리트에 선압축력을 도입하는 공법이다. 이때 수십톤에서 수백톤의 힘이 정착장치를 통해 콘크리트에 도입 되기 때문에 텐던, 정착장치, 콘크리트 상호간의 하중전달 및 상관관계가 구조물 전체의 성능 및 안전에 매우 중요한 영향을 끼친다 (Nawy, 2009;Kim et al, 2017 (Kim et al, 2012;Kim et al, 2016;Yang, Yim, et al, 2016 (Jeon et al, 2016; 정하중시험의 하중 도입방법을 Fig. 5에 도시하였고, 정하 중시험 방법 및 절차에 대한 사진을 Fig.…”