Early warning system for load distribution in automated warehouse based on seismic resilience evaluation

Abstract

As an integral part of the storage system in an automated warehouse, the racking structure can be altered for seismic performance by adjusting the distribution of loads, which is different from other building structures with uncertain load distribution. Therefore, there are two ways to improve the seismic resilience of racks: improving structural response and optimizing load distributions. The former has been widely studied, while the latter is rarely noticed. The objective of this study is to develop a method of seismic resilience evaluation and an early warning system of over-limit load distribution for racks with spine bracing. Based on the influence of load distribution on the seismic performance of racks with spine bracing, the contribution value of load positions was calculated to make additional corrections to the maximum stress ratio in load distribution samples obtained by genetic algorithm. Then, a formula for seismic resilience evaluation for racks with spine bracing was derived and its accuracy was validated to quantify the safety level of different load distribution patterns. An early warning system for over-limit load distribution was established and codified in a software package. A traffic light system including Green, Red, and Yellow were employed in the software package as an indicator of the load distribution safety level of racks. Finally, the system developed was applied to the actual racks in an automated tobacco warehouse in Nanjing. By adjusting loads in the least number of steps and the shortest distance, the racks changed from dangerous status (red light) to safe status (green light). The early warning system allows for rapid evaluation for the seismic resilience of racks without real-time finite element analysis, and is proved to be applicable, efficient and reliable.