Project Overview
Project P-2024-103 involved the structural design of heavy steel support structures for large water cooling fans and associated process pipelines at an amusement park complex in Buwaid, Saudi Arabia. Amusement park facilities generate significant cooling load from ride hydraulics, water attractions, and HVAC systems — the cooling towers and fan units that handle this load require structural supports capable of carrying substantial gravity loads combined with vibration forces from the rotating fan assemblies.
The structural scope covered the primary support frames for fan units (elevated above ground level for airflow clearance), the secondary framing for pipeline brackets and utility routing, and connection design for the interfaces between steel support frames and the reinforced concrete pad foundations.
Design Challenges
Combined Gravity and Dynamic Loading
Cooling fan units impose both static weight and dynamic forces on their support structures. The static weight includes the fan motor, fan housing, blade assembly, and associated piping connections. The dynamic component arises from fan blade imbalance — even a well-balanced fan assembly generates cyclic forces at blade-pass frequency. For large industrial fans, these dynamic forces can be 10–20% of the static weight and must be explicitly accounted for in the support structure design.
The design approach applied a dynamic load factor to the fan unit weight to generate a pseudo-static equivalent force representing the maximum dynamic demand. This is the standard approach for support structures subject to rotating machine loads where a full dynamic analysis is not warranted. The dynamic load factor was established from the equipment supplier's specifications for the specific fan units installed.
Pipeline Loads and Thermal Expansion
Process pipelines carrying water impose weight loads on bracket supports and also impose horizontal forces from thermal expansion. Pipelines operating at elevated temperatures expand longitudinally; if fully restrained by fixed supports, this generates large axial forces. The support design addressed this by providing guided supports (permitting axial movement while resisting lateral displacement) at regular intervals and fixed-point anchors where expansion joints were located.
The combination of pipe weight, water weight, and thermal expansion forces in the horizontal direction governed the design of the bracket and frame connections at multiple support locations.
AISC-360 Member Design
All steel members in the support structures were designed per AISC 360-22. The primary frames used HSS (hollow structural section) members for the vertical columns and horizontal beams — HSS sections were preferred for their closed cross-section, which provides high torsional stiffness (important for fan units that can impose eccentric loads) and good corrosion resistance with minimal internal void space to trap moisture in the outdoor Saudi environment.
Connections between HSS members used weld joints designed per AISC 360-22 Chapter J, with weld sizes determined by the governing load combination of gravity plus dynamic loading. All welds were specified to AWS D1.1 quality requirements with full inspection specified in the project documents.
Foundation Design
The fan support structures were founded on individual reinforced concrete pad footings. The footings were designed for the gravity loads from the fan units and steel framing, plus the horizontal forces from dynamic loading and pipe thermal expansion. Footing depths were established based on site geotechnical data to bear on competent soil below the surface layer, with appropriate allowance for the saline soil conditions typical of the Saudi Arabian coastal regions.
Anchor rod design for the base plates used the ACI 318-19 Appendix D strength provisions for cast-in anchor rods in tension, with the concrete breakout cone failure mode governing the embedment depth for the combined shear and tension anchor forces.
Documentation and Coordination
The design documentation was coordinated with the amusement park's mechanical and process engineering teams to ensure structural support locations and load assumptions matched the actual equipment layout and piping routes. This coordination was conducted via drawing exchange and technical queries answered directly by the senior structural engineer — ensuring that no assumptions in the structural model were inconsistent with the actual installation conditions.
Support structure design requires close coordination with equipment suppliers. Dynamic load factors, vibration isolation requirements, and maintenance access must all be confirmed before member sizing is finalised.