Earticle

In the seismical capacity evaluation for RC structure wall-slab joint is very important factor. Because lateral load is resistance element and gravity load resistance element are acted mutually in the wall-slab joint. In this paper, to improve the seismic capacity of the wall-slab joint in the existing wall type apartments experiment which improve and retrofit a seismic capacity by unequal angle bracing and carbon sheet attachment are carried out. These methods are also economic and simple in mitigating seismic hazard, improve earthquake-resistance performance, and reduce risk level of building occupants. From the experimental results, the change of strength, degration of stiffness, and energy dissipation are evaluated. It can be concluded that these methods are effective in improving the seismic performance.

콘크리트 판넬 부재의 폭발실험을 통해 콘크리트 구조물의 폭발에 대한 저항 성능을 정량적으로 평가하였다. 본 실험에서는 콘크리트의 강도, 보강재료를 변수로 총 8 가지 종류의 시편에 대하여 폭발실험을 수행하였다.

Through the test of concrete panel, we evaluate quantitatively the blast resistance performance of concrete structure. In this blast test, eight different panels were tested and the main variables are concrete strength(200 MPa, 24 MPa) and retrofitting materials(CFRP, PolyUrea, BFRP).

본 연구는 내진설계가 되어 있지 않은 필로티 건축물의 부족한 횡력을 보강할 수 있는 외부부착형 내진보강공법(Binding Column Method, BCM)을 제안하였다. 또한, 제안된 내진보강공법을 대상으로 보강실험체 4개, 기준 실험체 1개를 제작하여 반복가력 실험을 통하여 보강 전·후의 내진성능향상 효과를 검토하였다. 실험 결과, 기준 실험체(SC1)는 급격한 강도저하와 함께 취성적인 전단파괴의 양상을 나타낸 반면, BCM 공법을 적용한 실험체(SC2, SC3, SC4, SC5)는 강도 및 강성의 증가와 함께 에너지 흡수 능력이 큰 타원형의 이력특성을 나타내었다. 또한, 간격이 좁고 토크가 크며, L자형 강판의 두께가 두꺼울수록 보강효과가 향상됨을 알 수 있다. BCM공법 중 전단보강간격이 작고, 조임력 값이 크며, 연결철물이 두꺼운 SC4실험체가 가장 뛰어난 내진성능보강 효과를 나타내었다.

This study proposed a BCM(Binding Column Method) that can reinforce the insufficient seismic force of piloti buildings that are not designed for seismic resistance. In addition, 4 reinforcement specimens and 1 reference specimen were manufactured for the proposed seismic reinforcement method. The effect of improving seismic performance before and after reinforcement was examined through repeated loading tests. As a result of experiment, seismic reinforcement specimen with BCM system showed hysteretic characteristics of a large ellipse with great energy dissipation ability and increased strength and stiffness, while reference specimen showed rapid reduction in strength and brittle shear failure column. In addition, it can be seen that the reinforcing effect is improved as the gap is narrow, the torque is large, and the thickness of the L-shaped steel sheet is thicker. The SC4 specimen showed the best seismic performance reinforcement effect.

This study proposes an economically affordable method for retrofitting non-seismic detailed roof reinforced concrete beam-column joints (BCJs). The proposed method presents an innovative arrangement of steel plates designed to delay the propagation of joint shear cracks by externally applying compressive stress to the area surrounding the BCJs. Two full-scale sub-assemblage specimens for each exterior and interior roof BCJ, i.e., control and retrofitted specimens, were subjected to reversed cyclic loading to evaluate the proposed method. The retrofitted specimens displayed a preferable ductile behavior to the corresponding control specimen, with an enhancement in lateral strength by at least 100%. Furthermore, retrofitted specimens dissipated up to 13 times more energy than the control specimen by initiating a plastic hinge on beams or columns. These results indicated the effectiveness of the proposed method in preventing joint shear failure and improving the seismic behavior of roof BCJs.

Based on the nonlinear static analysis and the approximate seismic evaluation method adopted in "Guidelines for seismic performance evaluation for existing buildings, two methods to calculate strength demand for retrofitting individual structural walls in unreinforced masonry buildings are proposed." The displacement coefficient method to determine displacement demand from nonlinear static analysis results is used for the inverse calculation of overall strength demand required to reduce the displacement demand to a target value meeting the performance objective of the unreinforced masonry building to retrofit. A preliminary seismic evaluation method to screen out vulnerable buildings, of which detailed evaluation is necessary, is utilized to calculate overall strength demand without structural analysis based on the difference between the seismic demand and capacity. A system modification factor is introduced to the preliminary seismic evaluation method to reduce the strength demand considering inelastic deformation. The overall strength demand is distributed to the structural walls to retrofit based on the wall stiffness, including the remaining walls or otherwise. Four detached residential houses are modeled and analyzed using the nonlinear static and preliminary evaluation procedures to examine the proposed method.

본 연구에서는 이산화탄소 해양지중저장을 위한 운송 수단으로 활용될 $CO_2$ 운송선의 타당성조사 결과에 대하여 논한다. 중고 화물선 개조에 의한 $CO_2$ 운송선 확보와 신조에 의한 운송선 확보를 위한 개념 설계를 수행하였고, 이를 토대로 $CO_2$ 운송선의 획득 비용을 추정하였다. 마지막으로 가정한 시나리오에 대한 운용 방안을 검토하여 연간 운송량을 수송할 수 있는 필요 척수와 소요 비용을 함께 추정하였다.

This paper presents the feasibility study on $CO_2$ carrier for carbon dioxide marine geological storage. Conceptual design was carried out to acquire $CO_2$ carriers by retrofitting existing vessels and new ship-building. Based on conceptual design, the acquisition cost of $CO_2$ carriers was estimated. Finally, necessary expense and number of ships were estimated based on operational plans for the assumed scenario.