In an automotive plant, an automated storage and retrieval system (ASRS) synchronizes material handling flows from a part production line to an auto-assembly line. The part production line transfers parts on small-/large-sized pallets. The products on pallets are temporarily stored on the ASRS, and the ASRS retrieves the products upon request from the auto-assembly line. Each ASRS aisle is equipped with narrow-/wide-width racks for two pallet sizes. An ASRS aisle with narrow-/wide-width racks improves both storage space utilization and crane utilization while requiring delicate ASRS aisle design, i.e., the locations of the narrow-/wide-width racks in an ASRS aisle, and proper operation policies affect the ASRS performance over demand fluctuations. We focus on operation policies involving a common storage zone using wide-width racks for two pallet sizes and a storage-retrieval job-change for a crane based on assembly-line batch size. We model a discrete-event simulation model and conduct extensive experiments to evaluate operation policies. The simulation results address the best ASRS aisle design and suggest the most effective operation policies for the aisle design.

This study experimentally and analytically examines the seismic vulnerability of steel rack storage frames subjected to Korea earthquakes (2016 Gyeongju earthquake and 2017 Pohang earthquake). To achieve this aim, this study selects a three-story, one-bay steel rack frame with a typical configuration of rack frame in Korea. Firstly, the local behavior for frame components is examined by performing monotonic and/or cyclic load tests and the global response and dynamic characteristics of the subject rack frame are investigated by conducting a shaking table test. The analytical model of the rack frame is then created based on the experimental results and is used to perform nonlinear time history analyses with recorded Korea earthquakes. The seismic demand of the rack frame is considerably affected by the spectral acceleration response, instead of peak ground accelerations (peak floor accelerations). Moreover, the collapse fragility curve of the rack frame is developed using incremental dynamic analyses for the Gyeongju and Pohang earthquakes. Fragility results indicate that the ground motion characteristics of these earthquakes do not significantly affect the frame vulnerability at the collapse state.

본 논문은 적재설비의 바닥 구속조건에 따른 안전성을 평가하고자 한다. 평가를 위해서 국내에서 일반적으로 사용하고 있는 파렛트랙을 대상구조물로 선정하여 진동대 실험을 진행하였다. 진동대 실험을 위한 적재설비의 바닥 구속조건을 총 4가 지(1 bolt, 2 bolts, 4 bolts, Fixed)로 구분하여 진행하였다. 실험은 인공지진파를 증가시켜가며 진행하였고, 각 층별에서의 변위응답과 영구변형을 비교하였다. 이에 따른 실험 결과, 지진 강도에 따라 기둥 바닥의 구속조건을 달리 적용하는 것이 필요하다.

This paper intends to analyze the behavior characteristics of steel storage racks according to the constraints conditions by external loads such as seismic loads. In order to achieve these goals, the steel storage racks generally used in Korea were selected as target structures and shaking table tests were conducted. In order to confirm the behavior according to the constraints conditions, the foundation of the steel storage racks was constructed with three conditions (1 bolt, 4 bolts, fixed) and the experiment was carried out. As a result of the analysis of the data obtained through the experiment, it was confirmed that additional damper installation is needed rather than changing the condition of the bottom plate in order to secure the safety of the steel storage racks.

In this paper, a hydraulic damper was developed to protect the storage racks from earthquakes and the seismic performance of the storage racks was improved by applying the developed damper. In order to achieve these goals, the control capacity for the safety of the storage racks was determined, and a hydraulic damper satisfying the control capacity was designed and manufactured. In addition, the location of the hydraulic damper was determined through simulation. Finally, the shaking table test was carried out. As a result, the seismic performance improvement of the storage racks using the hydraulic damper was confirmed.