Industry Case Study: Summit at Copper Square-Phoenix Weitz Company
Challenge
Situation: The 23 story concrete shear wall residential building had 35 spandrel beams that were cored for pipe sleeves below the approved zone per criteria given by the engineer of record. This caused a 35 kip loss of capacity in downward shear. They need to regain the capacity lost by the cores.
Challenges: Using structural steel was not an option because it would lower the ceiling height in the hallways. Exterior post-tension cables would not work because the span was not wide enough and there was inconsistency in the location of the pipes. Many of the cores had pipes already installed. This created issues installing the carbon fiber. The solution was to cut the fiber, allowing the installers to wrap the fiber around the pipes.
Solution
Solution: Install one layer of unidirectional carbon fiber fabric the full width of the beams and wrap the complete beam. It was determined that any beam with a core 8 1/2" or less from the bottom needed carbon fiber support. This replaced the 35 kips structural strength lost by the cores while maintaining the ceiling height in the hallways. To maintain the structural strength of the fiber, all cuts on openings below 8 1/2" from the bottom of the beams were reinforced with an additional layer of fabric running in the horizontal direction.
Conclusion: The job was completed successfully and the contractor was happy with the results.
