Bok Tower is a transitional steel frame building built between 1927 and 1929, standing at 205 feet tall, and has eleven floors with the 56 bell carillon tower from levels 8 through 11. Problems started when cracks developed in the coquina brick largely in the areas of the spandrel beams. Highly distressed areas showed signs of bowing or displacement from the beam and masonry backup. In some cases, the coquina brick had failed completely creating a dangerous condition. Corrosion of horizontal structural steel members caused the coquina brick and underlying masonry to separate from the tower.

To address the corrosion problem and preserve of Bok Tower, the coquina brick was stripped back and rebuilt around the spandrel beams and an impressed current cathodic protection (ICCP) system was installed using a discrete anode system.

Product / System Used

Discrete anode ICCP system with embedded CP20 and CP200 embedded sensors, AchillesICP network management system and AiMS online management network.

Project Details

Anodes were installed by drilling internally within the bed joints of the brick work with low gauge interconnecting titanium wire (used to distribute current across a control zone) crimped using a proprietary titanium crimp. Steel connections were made directly by shot firing threaded studs to the spandrel beams to provide the cathode dc circuit with redundancy built-in to each zone.

The whole building is protected in 11-zones (1z per level). Corrosion potential and rate sensors were installed within the brickwork to directly measure the extent of protection afforded by the anodes to the steel surface. Four monitoring position were installed per zone. These probes and zonal controls are interrogated remotely using the C-Probe AchillesICP to the reporting management system (AiMS).

Project Impact

Through the use of ICCP and structural monitoring which has proven performance overtime, Bok Tower has been protected for 16 years (since 2007!). Sustainable resilience has been given to the historic structure and ensures no further damage to the exterior masonry.