• 대한건축학회논문집:구조계
• /
• 제34권1호
• /
• pp.19-26
• /
• 2018

After the Gyeongju earthquake, school buildings were designated as earthquake shelters. However, the ratio of designed for seismic of domestic school buildings is only 23.2% in Korea, and it is necessary to secure the seismic safety of those. Therefore, in this paper, a target building was selected before the seismic design criteria was established and the seismic performance of the building was evaluated. After the evaluation, reinforcement of the building was carried out using seismic retrofit systems which was previously tested. For this purpose, the evaluation was carried out using OpenSees program and the reliability of the seismic retrofit systems was also verified. In this way, we can more precisely reproduce the response of the building in case of actual earthquake and predict damage of the earthquake in the future.

• 한국지진공학회논문집
• /
• 제26권1호
• /
• pp.31-38
• /
• 2022

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.

• Steel and Composite Structures
• /
• 제45권5호
• /
• pp.683-695
• /
• 2022

Conventional braces are often used to provide stiffness to structures; however due to buckling they cannot be used as seismic energy dissipating elements. In this study, a seismic energy dissipation device is proposed which is comprised of a bracing member and a steel hysteretic damper made of steel hexagonal plates. The hexagonal shaped designated fuse causes formation of plastic hinges under axial deformation of the brace. The main advantages of this damper compared to conventional metallic dampers and buckling-restrained braces are the stable and controlled energy dissipation capability with ease of manufacture. The mechanical behavior of the damper is formulated first and a design procedure is provided. Next, the theoretical formulation and the efficiency of the damper are verified using finite element (FE) analyses. An analytical model of the damper is established and its efficiency is further investigated by applying it to seismic retrofit of a case study structure. The seismic performance of the structure is evaluated before and after retrofit in terms of maximum interstory drift ratio, top story displacement, residual displacement, and energy dissipation of dampers. Overall, the median of maximum interstory drift ratios is reduced from 3.8% to 1.6% and the residual displacement decreased in the x-direction which corresponds to the predominant mode shape of the structure. The analysis results show that the developed damper can provide cost-effective seismic protection of structures.

• 콘크리트학회논문집
• /
• 제22권1호
• /
• pp.11-18
• /
• 2010

이 연구에서는 변위-기반성능설계 개념에 의해 기존 철근콘크리트 기둥에 대하여 스틸재킷 보강에 의한 내진 성능개선의 성능설계 방법을 제시하였다. 스틸재킷 보강된 철근콘크리트 기둥에 대한 설계 변위 추정을 위해 스틸재킷 보강된 철근콘크리트 부재의 비선형 층상화 세그먼트 해석 모델을 제시하고, 성능기반설계에 의한 성능개선설계를 위하여 목표성능변위 및 설계지진가속도 조건에 대해 직접 변위-기반 설계 방법 및 변위계수법에 의한 내진성능개선 설계 방법을 제시하였다. 적용 예에서 이 방법은 기존 철근콘크리트 기둥과 비교하여 성능개선설계 결과 보강 전에 비해 변위 연성비 및 변위성능에서 크게 개선된 성능설계 결과를 제공해 주었다.

• 한국강구조학회 논문집
• /
• 제15권5호통권66호
• /
• pp.571-578
• /
• 2003

본 논문에서는 중심가새골조 가운데 가정 널리 사용되는 역V형 철골 가새골조의 내진거동을 탄소성 후좌굴해석에 의해 고찰하고, 압축가새의 좌굴이 최초로 발생한 층에 소성화가 집중되는 약층화 현상을 완화할 수 있는 효과적 내진보강 방안을 제시하고자 하였다. 즉 좌굴이 발생한 층에 집중되는 비탄성변형을 건물전체로 재분재하는 기능을 갖는 인장재(tie bar)를 삽입하여 내진성능을 효과적으로 개선할 수 있음을 입증하였다. 아울러 압축가새의 좌굴발생 순서를 감안하여 보강 인장재를 경제적으로 설계할 수 있는 실용적 설계방안을 제시하였다.

• Structural Engineering and Mechanics
• /
• 제44권5호
• /
• pp.611-631
• /
• 2012

The passive energy dissipation technology has been proven to be reliable and robust for recent practical applications. Various dampers or energy dissipation devices have been widely used in building structures for enhancing their performances during earthquakes, windstorm and other severe loading scenarios. This paper presents a simplified seismic design procedure for retrofitting earthquake-damaged frames with viscous dampers. With the scheme of designing the main frame and the supplemental viscous dampers respectively, the seismic analysis model of damped structure with viscous dampers and braces was studied. The specific analysis process was described and approach to parameter design of energy dissipation components was also proposed. The expected damping forces for damped frame were first obtained based on storey shear forces; and then they were optimized to meet different storey drift requirements. A retrofit project of a RC frame school building damaged in the 2008 Wenchuan earthquake was introduced as a case study. This building was retrofitted by using viscous dampers designed through the simplified design procedure proposed in this paper. Based on the case study, it is concluded that this simplified design procedure can be effectively used to make seismic retrofit design of earthquake-damaged RC frames with viscous dampers, so as to achieve structural performance objectives under different earthquake risk levels.

• 대한토목학회논문집
• /
• 제26권6A호
• /
• pp.965-976
• /
• 2006

지진하중에 대한 구조물의 생애주기비용 최적설계나 성능개선을 위해서는 생애주기 지진신뢰성해석에 기초한 접근이 불가피하다. 최근 몇몇 연구자들이 생애주기비용에 기초한 구조물의 내진설계 및 성능개선을 위한 방법론은 제안하여 왔지만, 대부분의 연구가 생애주기비용 산정을 위한 방법론 개발에 중점을 둔 연구이다. 따라서 대부분의 기존연구에서는 열화하는 구조물의 생애주기 지진신뢰성해석에 있어서 내진보강, 유지관리, 그리고 환경적 열화와 같은 주요한 인자들을 고려하지 못한 것이 사실이다. 이에 본 연구에서는 교량의 체계적인 생애주기 지진신뢰성해석 방법론을 제안하였고, 교량의 지진신뢰성해석을 위한 프로그램인 HPYER-DRAIN2DX-DS를 개발하였다. 개발된 프로그램은 내진보강이나 유지전략의 적용유무에 따른 예제교량의 생애주기 지진신뢰성해석 문제에 적용되었으며, 이를 통해 프로그램의 적용성을 검토해 보았다. 적용 예를 통해 본 연구에서 개발된 HPYER-DRAIN2DX-DS는 지진에 대한 교량의 생애주기비용 최적설계, 내진보강 및 유지관리에 있어 서 매우 유용한 도구로 사용될 수 있을 것으로 판단된다.

• Steel and Composite Structures
• /
• 제27권5호
• /
• pp.633-646
• /
• 2018

This study investigated the seismic performance of a hybrid damper composed of a steel slit plate and friction pads, and an optimum retrofit scheme was developed based on life cycle cost. A sample hybrid damper was tested under cyclic loading to confirm its validity as a damping device and to construct its nonlinear analysis model. The effectiveness of the optimum damper distribution schemes was investigated by comparing the seismic fragility and the life cycle costs of the model structure before and after the retrofit. The test results showed that the damper behaved stably throughout the loading history. Numerical analysis results showed that the slit-friction hybrid dampers optimally distributed based on life cycle cost proved to be effective in minimizing the failure probability and the repair cost after earthquakes.

• 한국지진공학회논문집
• /
• 제22권7호
• /
• pp.361-367
• /
• 2018

This study investigates the seismic performance of a hybrid seismic energy dissipation device composed of a viscoelastic damper and a steel slit damper connected in parallel. A moment-framed structure is designed without seismic load and is retrofitted with the hybrid dampers. The model structure is transformed into an equivalent simplified system to find out optimum story-wise damper distribution pattern using genetic algorithm. The effectiveness of the hybrid damper is investigated by fragility analysis of the structure with and without the dampers. The analysis results show that after seismic retrofit the probability of reaching damage states, especially the complete damage state, of the structure turn out to be significantly reduced.

• 한국디지털건축인테리어학회논문집
• /
• 제11권2호
• /
• pp.115-121
• /
• 2011

Occurrence of earthquakes have been increased all over the world and also, magnitude of earthquakes have been larger these days. Earthquake can be happened in Korea and is not a safe country any more. Many buildings are exposed at danger without any alternatives against earthquake in Korea. Among various kinds of buildings, school buildings are very important and urgent, because many students stays at school and young students have some difficulty to evacuate. Also, most existing school buildings in Korea were not designed considering earthquake resistant design codes. Thus, in this study, 3 types of braces were applied for seismic retrofits of existing school buildings using commercial structural analysis software and effective seismic retrofits were evaluated and discussed based on results by time history analysis.