New Construction with P-T: The Surf Club

Established in 1930 as a private social club, South Florida’s Surf Club was designed by one of Miami’s first architects, Russell Pancoast. Resting on Miami Beach, this iconic club has captivated guests from around the world with views of the Atlantic Ocean and Biscayne Bay.

The owners, seeking to restore Surf Club to its former glory, embarked on a project to revitalize and reinvigorate the historic property by adding a new 9-story high rise that would cantilever out over the existing structure. The new cantilevered addition would include new condominium residences and a five star hotel.

Understanding the Owner’s Vision

Investigations discovered that the original structure could not support additional loads on top of it. In order for the owner to preserve the historic building the new addition had to be built up and around the existing structure.

Transfer slabs would have to be used to support the upper levels over the building. A primary concern of the Owner included not disturbing guests’ view from the ground level, leading to the development of two unique hanging columns that would be supported by the roof.

The engineer of record selected STRUCTURAL TECHNOLOGIES to be a design consultant for the post-tensioning scope of the project to provide design support for all post-tensioning and rebar for both sky mats (transfer slabs), the sky hook beams and the hanging columns for the project.

Constructing the Sky Mats—B1 and B2

The two sky mats are 72” thick concrete slabs with a 50 foot long cantilever to support the new addition of the 9 story residential building. The 7,500 sq ft B1 sky mat required over 190,000 lbs. of post-tensioning. STRUCTURAL TECHNOLOGIES designed, manufactured and installed both bonded PT Bars and bonded VSL multistrand post-tensioning systems on the sky mat. Supported by one super column and 4 shear walls, the post-tensioning systems were designed to control deflection and give the sky mat the necessary strength. Additionally, PT bars were utilized to control the shear force around the column, a practice commonly performed in bridges but not normally seen in commercial applications.

The B2 sky mat totaled 7,400 sq ft and used over 110,000 lbs. of unbonded post-tensioning. STRUCTURAL TECHNOLOGIES assisted in the 3D modeling of this freestanding building with 3 sets of shear walls in order to finalize the design solution.

The large MEP openings around the shear walls of the B2 sky mat caused an issue with the punching shear force. In order to combat this issue, steel plates with studs almost as tall as the slab were designed and embedded in the concrete. This led to detailed coordination with the contractor because of the congestion of rebar and unbonded post-tensioning that went over these plates.

Additional shear reinforcement was designed into the slabs allowing the contractor to pour the concrete in 3 separate lifts. This approach accommodated cold joints and maintained control of concrete temperature while it cured, while also saving the contractor time and money.

The Hanging Columns

Another unique aspect of the project was the design of hanging columns and sky hook beams. The hanging columns began on level 5 spanning to the 12th floor and were supported by beams on the roof. These columns used bonded multi-strand VSL post-tensioning systems.

Design of Custom Bearing Steel Plate

STRUCTURAL TECHNOLOGIES custom designed and furnished steel bearing plates for the bottom of the hanging columns. These plates are recessed into the slab and have steel angles to control the punching shear at the column.

The Road to Revitalization

Despite numerous challenges and a congested work area the STRUCTURAL TECHNOLOGIES team has been able to offer unique post-tensioning design solutions featuring VSL products. STRUCTURAL TECHNOLOGIES scope of work on the project concluded in July 2015. Upon final construction completion in Spring of 2016, Surf Club welcomed a new host of spectators to its new addition to the Florida Coastline.