01. Project Challenges: Enclosing a Large Public Swimming Pool
Before installation, the open public pool faced four project-specific challenges documented in the source material:
- Strong solar exposure and evaporation: intense sunshine increased water evaporation and chemical degradation, affecting operating efficiency during peak daytime use.
- Dust and sand infiltration: seasonal wind carried debris into the pool basin, increasing filtration demand and recurring manual cleaning.
- 22 m column-free clear span: the operator required an unobstructed span across the pool and perimeter concourse to preserve swimming lanes, lifeguard sightlines and safe circulation.
- Flexible dual-mode operation: the enclosure needed to provide a protected indoor pool environment during adverse weather and retract for open-air swimming when conditions were suitable.
02. Motorized Retractable Pool Enclosure Design
2.1 Bi-Parting Center-Opening Telescopic Geometry
SUNRAY developed a center-opening telescopic enclosure so the 33 m long structure could retract toward both ends of the pool concourse. This layout reduces central stacking volume and distributes movement across two symmetrical halves.
- Symmetrical center split: both enclosure halves retract outward from the center.
- Long-span multi-arch form: the structure covers the 22 m clear span without intermediate interior columns.
- Polycarbonate enclosure: 6 mm multi-layer UV co-extrusion solid sheets form the roof and wall envelope.
- Architectural integration: the project source specifies a charcoal-gray powder-coated finish coordinated with the surrounding facility.
03. Shop Drawings and Long-Span Structural Detailing
The engineering package translated the concept into fabrication and installation drawings with full-scale dimensions for the 33 m × 22 m enclosure.
- Roof framing and plan elevation: 33,000 mm overall length with track centerlines and synchronized drive layouts.
- Transverse geometry: 22,000 mm clear span, 20,504 mm internal clearance span, 7,000 mm ridge height and 3,596 mm eaves height.
- Main rafters: 258 × 110 × 8 mm 6063-T6 aluminum extrusion.
- Internal reinforcement: 223 mm wide × 25 mm thick galvanized Q235 steel flitch plate, laser-cut and bolted through the profile web chambers.
- Sealing and drainage: continuous EPDM gaskets combined with secondary aluminum drainage channels at panel overlap joints.
04. FEA and Wind-Load Verification
4.1 MIDAS/Gen 2022 Structural Model
Because of the 22 m clear span and 7 m ridge height, the project source includes a spatial 3D finite element analysis completed in MIDAS/Gen 2022. The model contains 1,450 nodes and 2,825 elements, including 1,543 beam elements and 1,282 plate elements.
4.2 Material and Wind Design Inputs
- 6063-T6 aluminum: yield strength fy = 160 MPa; project design value fd = 140 MPa; shear design value fvd = 81 MPa; density = 2,648 kg/m³.
- Q235 steel reinforcement: yield strength fy = 235 MPa; project design strength fd = 215 MPa; shear design value fvd = 125 MPa.
- Design wind speed: 36.9 m/s.
- Basic wind pressure: W0 = 0.85 kN/m².
- Peak governing wind pressure: Wk = 1.16 kN/m².
- Roof uplift wind suction: Wk = -1.01 kN/m².
4.3 Stress, Deflection and Foundation Reactions
- Maximum calculated stress: 101.0 MPa under the stated critical load combination, compared with a project allowable stress of 140.0 MPa.
- Maximum spatial displacement: 19.0 cm under the stated standard load combinations; the source records checks against L/250 vertical deflection and H/150 column-top lateral drift criteria.
- Maximum column-foot reaction: Fx = -7.99 kN; Fy = -4.91 kN; Fz = -26.08 kN.
05. Precision Manufacturing and Quality Control
The project source emphasizes machining accuracy because tracking deviations across a large moving span can affect drive alignment and smooth operation.
- CNC profile processing: compound-angle milling, drainage-slot machining and bolt-hole positioning on the primary aluminum rafters.
- Laser-cut reinforcement plates: 25 mm galvanized steel plates fabricated with precision bolt patterns and weight-relief openings.
- Architectural powder coating: multi-stage pretreatment and outdoor-grade powder coating; the source states 2,000+ hours of neutral salt-spray resistance.
06. 1:1 Full-Scale Factory Pre-Assembly and Commissioning
Before export, SUNRAY carried out a 1:1 full-scale factory pre-assembly on full-length tracks. This stage was used to verify component fit-up, track geometry, structural clearances and motorized movement before shipment.
- Full-span assembly: the complete 22 m span × 33 m length arch structure was erected at the factory test site.
- Drive and track testing: the source records electric drive synchronization, remote-control response and anti-lift safety checks over more than 100 continuous operating cycles.
- Clearance verification: the full-scale assembly was checked for structural and operational clearance.
- Component coding: rafters, cross-ties and track rails were marked with alphanumeric IDs corresponding to the assembly documentation.
07. Export Packaging and Container Preparation
- Protective wrapping: architectural profiles were individually wrapped to reduce transport abrasion.
- Bundled long members: structural profiles were strapped into transport bundles with timber separation.
- Moisture-resistant outer packaging: bundles were covered for marine shipment.
- Container planning: the project source records loading planning for 40 ft HQ sea containers with itemized packing manifests.
08. On-Site Installation and Technical Supervision
After overseas delivery, the modular enclosure was erected with the local contractor team using prepared components and crane-assisted lifting.
- Bolted field assembly: the source records pre-drilled components assembled without on-site cutting or welding.
- Crane-assisted modular hoisting: roof and wall structural modules were lifted sequentially onto leveled guide tracks.
- SUNRAY technical supervision: project specialists supported rail calibration, electric motor synchronization and weather-seal installation.
09. Project Results: Flexible Enclosed and Open-Air Pool Operation
The completed motorized retractable pool enclosure gives the facility a single structure that supports both protected indoor use and open-air swimming. The source project records the following operating results:
- Approximately 180-second opening or closing time for the complete 22 m × 33 m enclosure using the motorized drive.
- 6 mm polycarbonate panels stated to block 99.9% of UV radiation while preserving high natural daylight transmission.
- Project records report reduced dust and debris ingress, together with lower filtration backwash frequency and chemical usage.
Why This Solution Fits Large Public and Commercial Pools
- Large column-free coverage supports clear swimming lanes, lifeguard sightlines and deck circulation.
- Motorized telescopic opening allows one facility to switch between enclosed and open-air operating modes.
- FEA verification, detailed shop drawings and 1:1 factory pre-assembly reduce uncertainty before overseas installation.
- Modular fabrication and bolted assembly support controlled cross-border delivery and on-site erection.
Project Testimonial
“Executing a 22-meter clear span over an active public pool seemed like a high-risk structural challenge. Sunray's structural calculations, rigorous pre-assembly in China, and turnkey bolted engineering eliminated all on-site surprises. The pool enclosure survived multiple desert storm seasons with zero leaks, zero track binding, and tremendous public acclaim.”
- DANZIV Nissim Project Management Team, Middle East
Planning a Public Pool Enclosure Project?
SUNRAY develops customized retractable enclosure solutions for public swimming pools, resorts, aquatic centers and commercial pool facilities. Project engineering can be developed around clear span, local wind conditions, opening requirements, architectural integration and installation constraints.