Our Products At Work in the Field


RenewWrap® System: Slab and Column Strengthening


Rosslyn, VA
December 17, 2017

Overview
One of the world's largest packaged food and beverage companies recently relocated its United States corporate headquarters to the region's tallest building in Rosslyn, VA, just across the Potomac River from the Georgetown area of Washington, D.C. The corporation retained Gensler to design a complete renovation of the lobby, mezzanine area and multiple floors within the building. To accommodate the needs of the renovation, including the installation of a prominent staircase between floors, large openings were required within the reinforced concrete floor slabs. In addition, a post-tensioned floor slab at the mezzanine level was demolished to create an impressive two-story lobby, which left a single column that measured two stories high.

Challenge
No concrete repairs were necessary for the project, but demolition of the continuous reinforced two-way concrete floor slabs for the staircase openings created flexural deficiencies in the slabs, which were in the bays adjacent to the openings. Reinforcing the bottoms of the slabs to satisfy the increased flexural demands without compromising the aesthetic requirements of the renovation design were critical.

The capacity and slenderness of the two-story column in the lobby were checked and determined to be acceptable, but at mid-height of the exposed column, the lap splices of the compression steel were no longer confined when the post-tensioned slab was demolished. The confinement restoration also needed to meet the rigorous aesthetic requirements for the renovation.

Results
The engineer of record recommended an FRP system for the project over a more traditional retrofit strategy due to its minimal impact to the aesthetics of the strengthened structure. The simple and quick installation had nominal effects to the overall project schedule. Freyssinet proposed the RenewWrap CF600 FRP strengthening system and took advantage of the EZ-Slit fabric since the design made use of 6” wide strips. 

Arlington County also required a two-hour fire rating for the strengthened floor slab. An approved fire protection material was installed over the cured FRP system to protect the existing reinforcing steel and fulfill the rating stipulations of the structure.

RenewWrap_Slab and Column_Rosslyn_Preparing ColumnRenewWrap_Slab and Column_Rosslyn_Completed ColumnRenewWrap_Column and Slab_Rosslyn_Slab InstallRenewWrap_Column and Slab_Rosslyn_Slab ReinforcementRenewWrap_Column and Slab_Rosslyn_Bottom of Slab