• Smart Structures and Systems
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• 제25권4호
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• pp.487-499
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• 2020

This paper proposes a novel approach to model updating for a large-scale cable-stayed bridge based on ambient vibration tests coupled with a hybrid metaheuristic search algorithm. Vibration measurements are carried out under excitation sources of passing vehicles and wind. Based on the measured structural dynamic characteristics, a finite element (FE) model is updated. For long-span bridges, ambient vibration test (AVT) is the most effective vibration testing technique because ambient excitation is freely available, whereas a forced vibration test (FVT) requires considerable efforts to install actuators such as shakers to produce measurable responses. Particle swarm optimization (PSO) is a famous metaheuristic algorithm applied successfully in numerous fields over the last decades. However, PSO has big drawbacks that may decrease its efficiency in tackling the optimization problems. A possible drawback of PSO is premature convergence leading to low convergence level, particularly in complicated multi-peak search issues. On the other hand, PSO not only depends crucially on the quality of initial populations, but also it is impossible to improve the quality of new generations. If the positions of initial particles are far from the global best, it may be difficult to seek the best solution. To overcome the drawbacks of PSO, we propose a hybrid algorithm combining GA with an improved PSO (HGAIPSO). Two striking characteristics of HGAIPSO are briefly described as follows: (1) because of possessing crossover and mutation operators, GA is applied to generate the initial elite populations and (2) those populations are then employed to seek the best solution based on the global search capacity of IPSO that can tackle the problem of premature convergence of PSO. The results show that HGAIPSO not only identifies uncertain parameters of the considered bridge accurately, but also outperforms than PSO, improved PSO (IPSO), and a combination of GA and PSO (HGAPSO) in terms of convergence level and accuracy.

• 한국재난정보학회 논문집
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• 제11권2호
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• pp.203-209
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• 2015

열감지기는 화재시 발생되는 열을 감지하는 것으로 모든 소방대상물에 일반적으로 사용되는 자동화재탐지설비의 중요한 핵심 요소이다. 열감지기는 스포트(spot)형과 분포형으로 구분되며, 스포트형에는 차동식과 정온식이 있다. 이러한 열감지기는 실제 화재시 작동시간 및 작동온도 등 반응의 민감도에 따라 인명과 재산 손실에 큰 영향을 준다. 국내에서는 스프링클러 헤드제품에 응답시간지수를 도입하여 사용하고 있으나, 열감지기에 대해서는 현재 적용이 되어지지 않고 있으며, 반응의 민감도를 표시하는 응답시간지수의 도입이 필수적으로 본 연구에서는 국내 생산된 정온식 스포트형 열감지기와 다이아프램형 및 반도체 형식의 차동식 스포트형 열감지기에 대하여 풍동실험 및 화재실험을 통하여 응답시간지수, 작동시간, 작동온도 등에 대하여 연구하였다. 응답시간지수를 적용한 열감지기를 설치하여 신속한 경보로 인한 국민의 생명과 재산손실을 줄이는데 도움을 주고자 한다.