지지부가 움직이는 모바일하버용 크레인의 동적 응답 최적설계

Abstract

모바일하버는 해상에서 상∙ 하역작업을 하는 새로운 해상물류 시스템이며 모바일하버에 설치되는 크레인은 해상에서 작업하는 대형 구조물이므로 파도에 의해 발생하는 지지부의 운동으로 관성력의 영향을 크게 받는다. 이렇듯 작업환경이 육상용 크레인보다 위험하므로 크레인의 안전성에 대한 정확한 검증이 요구되고, 설계비용 절감 등을 위해 구조물의 경량화가 필요하다. 본 연구에서는 위 두 가지 조건을 동시에 만족하는 크레인을 설계하기 위해 동적 응답 최적화를 이용해 구조 설계를 수행한다. 동적 응답 최적화의 방법 중 등가정하중법을 사용한다. 등가정하중법은 동하중을 등가의 정하중으로 변환한 후, 정적 응답 최적화기법을 사용해 문제를 해결하는 동적 응답 최적설계 방법이다. 등가정하중을 구하기 위해서는 동적 응답 변위 벡터를 사용하는 방법을 사용한다. 그러나 해상에서 작업하는 모바일하버용 크레인 크레인과 같이 지지부가 움직이는 구조물에서는 동적 응답의 절대 변위 벡터를 그대로 사용하면 등가정하중이 부정확하게 계산되는 문제가 있다. 정확한 등가정하중 산출을 위해 상대 변위 벡터를 이용한 등가정하중 산출 방법을 개발하고, 이를 기반으로 지지부가 움직이는 문제에서의 등가정하중법을 새롭게 제안한다. 제안한 방법을 모바일하버용 크레인에 적용해 안전조건을 만족하고 경량화된 크레인을 설계한다. 또한, 동적 계수를 이용한 정적 응답 최적설계를 적용했을 때의 결과와 비교하여 제안한 동적 응답 최적설계의 우수성을 검증한다.|The mobile harbor is a new innovative system that delivers containers from a containership to a harbor without good infrastructure. The mobile harbor typically has a container crane on it. The crane installed in a mobile harbor is influenced by the inertia force that occurs from a moving support. Thus an accurate safety verification considering the moving support is required. And light weight is pursued in design for low production cost. Dynamic response optimization is a design method to achieve these two requirements. The present study uses the equivalent static loads method which can handle dynamic response structural optimization. Equivalent static loads are the loads which can generate the same displacement field from static analysis with the one from dynamic analysis. The equivalent static loads method transforms dynamic loads to equivalent static loads, and then solves static response structural optimization with the transformed equivalent static loads. Dynamic response analysis is conducted again with the results of static response optimization and the process cyclically proceeds until the convergence criterion is satisfied. A new method is proposed to consider the moving supports. Relative displacements are utilized to evaluate the equivalent static loads from the moving supports. Small scale problems are solved to validate the proposed method and a large scale problem with the mobile harbor crane is optimized. The results are compared with the conventional static response structural optimization with dynamic factors.; The mobile harbor is a new innovative system that delivers containers from a containership to a harbor without good infrastructure. The mobile harbor typically has a container crane on it. The crane installed in a mobile harbor is influenced by the inertia force that occurs from a moving support. Thus an accurate safety verification considering the moving support is required. And light weight is pursued in design for low production cost. Dynamic response optimization is a design method to achieve these two requirements. The present study uses the equivalent static loads method which can handle dynamic response structural optimization. Equivalent static loads are the loads which can generate the same displacement field from static analysis with the one from dynamic analysis. The equivalent static loads method transforms dynamic loads to equivalent static loads, and then solves static response structural optimization with the transformed equivalent static loads. Dynamic response analysis is conducted again with the results of static response optimization and the process cyclically proceeds until the convergence criterion is satisfied. A new method is proposed to consider the moving supports. Relative displacements are utilized to evaluate the equivalent static loads from the moving supports. Small scale problems are solved to validate the proposed method and a large scale problem with the mobile harbor crane is optimized. The results are compared with the conventional static response structural optimization with dynamic factors.