The Evaluation of flexure performance of SCP modules for LNG outer tank

LNG 외조탱크 적용을 위한 SCP 모듈의 휨성능 평가

Abstract

When constructing LNG storage structures using the cast-in-place method in extreme areas, the construction cost and time may be increased due to the poor working environments and conditions. Therefore, demand for modular energy storage tanks is increasing. In this study, we propose using an SCP module as an alternative for lighter-weight LNG storage tanks. The purpose of this study is to evaluate the feasibility of LNG storage outer tanks by performing bending tests on the thickness of composite steel plate concrete under field conditions. The loads on specimens with thicknesses of 100 mm and 200 mm were linearly increased to the design final loads of 413 kN and 822 kN, respectively. The slope was rapidly changed, and fracture occurred. The two test conditions showed linear behavior until the steel plate yielded, and after an extreme load behavior, sudden yielding of the steel plate yield occurred in the SCP bending test according to the INCA guidelines. The results satisfied the design flexural load and showed the possibility of using the specimens in a modular LNG outer tank. However, it is necessary to evaluate the structural performance of the SCP by performing compression and shear tests in future research.

극한지에서 LNG 저장구조물을 건설할 때 현장 타설 방식으로 제작 및 시공되는 경우, 열악한 작업 환경 및 조건으로 의해 공사금액 및 공사기간이 증가되는 문제점이 발생할 수 있어 모듈형 에너지 저장탱크에 대한 요구가 높아지고 있다. 이에 본 연구에서는 LNG 연료 저장탱크의 경량화를 위해 SCP 모듈의 사용을 대안으로 제시하고자 하였다. 이에 SCP 모듈을 두께별로 제작하고 그에 따른 휨성능을 평가함으로써 SCP 구조의 LNG 연료 저장탱크에 대한 현장적용 가능성을 평가하고자 하였다. 실험 결과 두께 100mm 실험체는 설계상 극한하중인 413 kN까지는 선형을 유지하면서 증가하다가 기울기가 급격하게 변하면서 파괴되었다. 두께 200mm 실험체 또한 설계상 극한하중인 약 822 kN까지 선형을 유지하다가 파괴양상을 보였다. 두 조건 모두 SCP의 휨 시험에서 INCA guidance의 기준대로 철판이 항복에 도달할 때까지 선형 거동을 나타내었다가 극한하중이후에는 급격한 철판 항복을 동반하는 거동을 하였다. 또한, 목표로 제시한 설계 휨강도를 만족하여 SCP 모듈을 활용하여 LNG 저장탱크 외조구조물에 적용이 가능할 것으로 판단되었다. 추후 압축, 전단 시험 등을 추가로 진행하여 SCP의 구조성능에 대한 평가가 필요할 것으로 판단된다.

Fig. 1. Steel concrete plate(SCP) module [1] (a) Concept [3] (b) Section

Fig. 2. Manufacture of test specimens (a) Placing concrete using small sized bucket (b) View of SCP test specimens for testing of structural performance

Fig. 3. Test method of bending member (a) Concept of loading (b) View of experiment on a bending member

Fig. 4. Gauges locations of specimens (a) LVDT locations (b) Concrete strain gauges locations (c) Top and bottom skin plate strain gauges locations

Fig. 5. Compressive strength test result

Fig. 6. Test results (Bd-100mm-#02) (a) Load-displacement curve (Bd-100mm-#02) (b) Load-compressive strain curve of upper steel plate (Bd-100mm-#02) (c) Load-tensile strain curve of lower steel plate (Bd-100mm-#02) (d) Comparison of load - strain curves of concrete (Bd-100mm-#02)

Fig. 7. Displacement shape with load increase (Bd-100mm-#02)

Fig. 8. Test results (Bd-200mm-#05) (a) Load-displacement curve (Bd-100mm-#02) (b) Load-compressive strain curve of upper steel plate (Bd-200mm-#05) (c) Load-tensile strain curve of lower steel plate (Bd-200mm-#05) (d) Comparison of load - strain curves of concrete (Bd-200mm-#05)

Fig. 9. Displacement shape with load increase (Bd-200mm-#05)

Fig. 10. Test results (a) Load-Displacement Curve of Middle Section (bending member) (b) Load-Compressive Strain Rate of Upper Section of Steel Plate (bending member_ST-2) (c) Load-Compressive Strain Rate of Lower Section of Steel Plate (bending member_SB-2)

Table 1. Maximum resistance moment according to stud clearance and thickness

Table 2. Concrete mixing design

Table 3. Guideline for high-filled concrete [7]

Table 4. Test Specimen Data

Table 5. Test result of fresh concrete