CTLGroup was retained to evaluate the extent of cracking in the concrete from of a 326-ft tall, seven-level preheater tower, and formulate a repair plan on a fast-track basis. CTLGroup mobilized at the site in less than 24 hours and performed an initial structural safety assessment. A comprehensive structural evaluation indicated that the structure required strengthening.
After considering structural capacity and serviceability requirements, durability issues, the high-temperature operating environment, constructibility, and an aggressive construction schedule, the team recommended a retrofit consisting of bonded post-tensioning within internal holes core-drilled in the beams. This solution required precisiondrilling horizontal holes more than 90 ft long in the beams of the elevated frame structure, without cutting existing embedded reinforcement. We used nondestructive impulse radar testing to locate existing embedded reinforcing steel, as well as to monitor the drilled holes’ trajectory. This process helped ensure proper tendon alignment and prevent damage to embedded steel.
The repairs were executed on a fast track and included working high on the exposed structure through a cold winter with severe wind conditions. The unique retrofit resulted in a structure that is stronger, more serviceable, and more durable than the original tower.
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