Movement joints and submersed connectors
Given the pool was built atop three high rise towers, engineers had to consider the fact that wind and the force of gravity would cause the towers to sway and move independently of one another. The Skypark as a whole is designed for wind pressures of up to 113 kilometres per hour (km/h) (70 miles per hour [mph]). To put this in perspective, at about 21 km/h (13 mph), it becomes uncomfortable to sit outside; at 35 km/h (22 mph), it is difficult to stand without swaying.
As such, beneath the main pools are four movement joints, designed to help the pools withstand the natural motion of the towers. Each joint has a unique range of motion; the largest movement joint can accommodate a total range of motion of 500 mm (19.6 in.).
The SkyPark pool comprises three separate shells; the middle pool shell is constructed atop the middle tower; the outer shells are constructed on bridges that connect the middle tower with the outer two. The structural bridges between each hotel tower were installed with a 76 mm (3-in.) pitch to accommodate the finished weight of the pool when filled with water.
The three pool shells are joined by uniquely-designed connectors at each of the movement joints. The connectors are submersed, allowing water to flow over them, creating one large recirculating body of water. The connectors double as shallow-water terraces for pool loungers.
Jacking system
In addition to wind, the hotel towers are subject to settlement over time that could cause the original construction plane of any one of the three pool shells to slope.
As such, engineers designed and manufactured custom jack legs to allow for future adjustment at more than 500 points beneath the pool system. This jacking system is important primarily because of the 146-m (478-ft) weir (infinity) edge. In order for the weir edge of the pool to function properly, its elevation has to be within 3 mm (0.1 in.) of its original length, which translates to less than 3.75 mm (0.125 in.) over the entire 146 m (478 ft).
A scale model of the enclosures and submersed connectors was fabricated to simulate the movement joint and test different sealing methods. Using the mock-up, engineers were able to troubleshoot and modify the sealing method to provide a superior product never before used in elevated pool construction.
A group effort
Natare had a number of integral partners who helped make the Marina Bay Sands project a success. The design team included Jaron Lubin of Moshe Safdie and Associates; Jose Silva of Aedas; Howard Fields of Howard Fields Associates International; and Marcus Ng and David Yeo of Innovez. Designers and engineers for Marina Bay Sands included Tony McKee, Justin Hotton and Mark Avery; Cory Dalton, Mark Teeter and Ramey Durbin of Ter Horse, Lamson & Fisk Structural Engineering; and Steve Hoffman of Hoffman Engineering.
Marie Lewis is the communications director for Natare Corporation in Indianapolis, Ind. Natare designs and builds swimming pools, spas and specialty equipment for aquatic facilities around the world. She can be reached via mkl@natare.com or by visiting www.natare.com.
