Wind and Seismic Design Considerations for Ladders and Platforms Installed Around Large Cylindrical Vessels and Supporting Structures

Abstract For non-building structures not similar to buildings, there are distinct design requirements and considerations for ladders and platforms subjected to gravity and lateral loads. The design requirements for ladders and platforms are governed by industry standards including ASME STS-1 (American Society of Mechanical Engineers, Steel Stacks) and ASCE 7-16 (American Society of Civil Engineers, Minimum Design Loads and Associated Criteria for Buildings and Other Structures). Ladders and platforms design should also satisfy the requirements per OSHA (Occupational Safety and Health Administration). This paper will focus on wind and seismic design considerations for ladders and platform installed around cylindrical vessels. The industry standards including ASME, ASCE and OSHA will be reviewed to show their application and limitations. The effect of seismic loads on ladders and platform is addressed in accordance with ASCE 7-16 Chapter 13, Seismic design requirements for nonstructural components, and Chapter 29.4, Design wind loads for other structures. A case study detailing the linear elastic analysis and design for ladders and platform components in high wind and seismic zone including railing, platform beams, braces / kickers and connections, using FEA and hand calculations is reviewed. Based on this study, design guidelines for ladders and platform installed around large cylindrical vessel are provided.