Improved Resiliency of Warehouse Structures Subject to Sequential Forklift Impact and Extreme Wind Loading Events

This paper presents the first-known study on the resiliency of warehouse columns subject to sequential loading events of forklift impact and extreme wind loading utilizing numerical simulation. The analysis employs the restart program in the finite-element (FE) modeling software package LS-DYNA (version R15.0.2) to sequentially simulate the forklift impact and wind load events. The simulation begins with the application of a dynamic load to represent the impact of a forklift on a warehouse column, capturing the resulting postimpact damage state. Following this, the structurally compromised system is subjected to tornado-induced wind loads to assess the combined effects of these sequential hazards. This novel methodology enables a comprehensive evaluation of stress distributions under combined loading conditions. The analysis results indicate that, in the worst-case scenario under tornado wind loading, the post-corner-impact structure exceeds the yield limit after just one impact event, while the structures subjected to side impact and mid impact reach the yield limit after three impacts. The structure stresses for the same number of impact events remain below the allowable strength design limit under impact-only conditions. This discrepancy may create a false sense of security, because columns remain within limits under impacts, but combined tornado and impact loads can cause critical stresses in the roof members, potentially placing the entire structure at risk of failure. To address this issue, several mitigation strategies can be implemented. First, increasing the cross-sectional size of columns can enhance their capacity to withstand sequential loading. Second, protecting columns that are likely to be impacted, such as through the use of column jackets or other protective measures, can reduce damage from forklift collisions. These measures can improve the overall resilience of the warehouse structure, mitigating the risk of failure under combined loading conditions.