Round and Round
BY CARL ZANIER, P.E., AND RAMON GILSANZ, S.E., P.E., GILSANZ MURRAY STEFICEK LLP
JANE’S CAROUSEL has come a long way in its 90-plus years of existence.
The carousel dates back to 1922, when it was initially installed in Idora Park in Youngstown, Ohio. In the early 1980s, it was purchased for installation in Empire-Fulton Ferry State Park (now Brooklyn Bridge Park) in the Dumbo neighborhood of Brooklyn. Painstakingly restored by Jane Walentas over the course of more than two decades in her Dumbo studio, it now resides in a pavilion in the park and is the first carousel to be placed on the National Register of Historic Places.
The 5,000-sq.-ft, steel-framed acrylic pavilion, with a tensile roof structure, was designed by prominent French architect Atelier Jean Nouvel. Gilsanz Murray Steficek LLP (GMS) assisted the executive architect, TA Dumbleton Architect PC, in developing the foundation design, steel superstructure and structural support details for the clear wall panels, operable panels and tensile roof that form the pavilion.
The floor slab is concrete on metal deck; an access hatch between the spinning platform of the carousel and the stationary motor housing provides access to the mechanical space below. Plates with shear studs were cast into the interior foundation walls and studs were welded onto the metal deck to enable it to act compositely.
The structure is supported on a raft foundation that floats on the site. The weight of the completed structure, with the 25-ton carousel installed, is less than the weight of the soil displaced by the structure below grade. With the organic fill soil profile of this site, the raft foundation was more economical than a pile foundation.
The four corners of the mechanical space are chamfered in plan, forming an octagonal space on the interior. These corners have 5-ft-wide diagonal walls forming the chamfer and provide piers in the foundations to support the four HSS24×0.500, ASTM A500-Grade B columns. These four columns are 27 ft high and spaced about 60 ft apart to support the the roof.
At the roof, the columns are moment connected to 37-in.-deep × 26-in.-wide box girders, creating the four sides of the pavilion. These box girders were designed to resist not only the vertical gravity loads, but also the tensile forces from the roof and the wind loads from the walls. The tensile roof is comprised of 1¼-in.-thick glass with a steel rod and strut support system. Coped W12×79 beams cantilever out from the box girder to support a continuous L12×12×½, which forms the frame for the operable doors. W10×100s cantilever in toward the center of the roof to provide a connection point for the tensile structure. Posting up at the end of each W10 are two MC6×18s, which support the curved HSS8×8×3/8 tension ring.
Two of the clear walls of the pavilion are 4½-in. acrylic, non-operable panels with a vertical span 27 ft; the panels are 10 ft wide. The connection at the base of the panels was developed to provide fixity, thereby limiting their deflections. The other two walls are made of operable 1-in. acrylic and slide open to provide access to the carousel.