This project involves the structural redesign of a segment of a larger steel pipe rack system in an oil refinery in Carson, California. The pipe rack system originally has two levels of 10 pipes and a third level of electrical cable running through the entirety of it. The client wants to support an air cooler addition and its respective maintenance platform and access ladders necessary for technicians to access the air cooler. The design is required to safely resist gravity (dead and live loads) and lateral (wind, seismic, and thermal) forces while meeting industry standards and serviceability requirements. The final design utilized steel framing with concrete fireproofing, engineered connections, and isolated concrete footings in compliance with professional (American Society of Civil Engineers) and material (American Institute of Steel Construction & American Concrete Institute) standards.
Pipe Rack System
Summary
Technical Approach/Methodology
The design process began by creating an initial design of the pipe rack system. Using that design as a base project requirements, site parameters, and applicable design codes were established. Using the ASCE 7-22, the strongest force using a combination of these structural forces was used for the preliminary design:
- dead load
- live load
- operating/equipment load
- wind load
- seismic load
- thermal load
The force was then used to size the beams and columns through iterations of hand calculations, excel calculations, and RISA modeling prioritizing checks for strength, buckling, yielding, and deflection. Continuing with RISA-3D, the beams and columns went through more iterations of sizing due to simulation failure until coming to a design that was both cost-effective and was successful in all of the limit state checks. Then, RISA Connections and RISA Foundations were used to design their respective areas using both steel (AISC) and concrete (ACI) provisions.
Outcomes
The final outcome was a pipe rack system that could support the weight of an air cooler while also resisting the additional gravity and lateral forces that came with the additional height and structural requirements.
- The steel beams, columns, and bracing provide the structure with minimal deflection and stability.
- The connections ensure that all internal forces can be transferred from section to section without disconnecting or falling apart.
- The foundations stabilize the entire structure so that it does not slide or overturn.
The budget that was created included the bulk materials, labor costs (both on and off the site), and machinery to a total cost of approximately $403,000.