Inspection by plant personnel revealed cracking in the concrete frame of a 326-ft-tall, 7-level preheater tower. On-site plant engineers deemed the cracking significant, as the structure supports critical manufacturing process equipment. A structural engineering consulting firm was retained to evaluate the extent of the problem and formulate a repair plan. The firm 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.
Restoration consultants were engaged to assist locally with engineering and construction administration. A specialty repair contractor also was engaged to review the constructibility of several alternate repair schemes and maintain the fast-track schedule.
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 drilled in the beams. This solution was quite extraordinary, as it required precision-drilling horizontal holes up to 87 ft long in the beams of the elevated frame structure, without cutting existing embedded reinforcement.
Nondestructive impulse radar testing was used 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 cored holes served as post-tensioning ducts.
The repairs were executed quickly and under challenging circumstances, including 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.
Award of Excellence
Eden Roc Hotel
High-Rise — Tadjer-Cohen-Edelson Associates, Inc.
Award of Excellence
Jefferson Davis Monument Restoration
Historic — Wiss, Janney, Elstner Associates, Inc.
Award of Excellence
Coral Word Ocean Park
Longevity — Matcor, Inc.
Award of Excellence
Temple Street Parking Garage
Parking Structures — National Restoration Systems, Inc.
Award of Excellence
KBP Coil Coaters Structural Fire Repair
Special Projects — Restruction Corporation
Award of Excellence
Hopkins and Clinton Streets Bridge Rehabilitation
Transportation — Sika Corporation
Award of Merit
Renovation of Baltimore’s Historic Hippodrome Theater
Historic — Structural Preservation Systems, Inc.
Award of Merit
Restoration of the Ca’d’Zan Mansion
Historic — Schnell Contractors, Inc.
Award of Merit
Restoration of Two Historic Stadiums in Lakeland, Florida
Historic — Sika Corporation
Award of Merit
Lanark Distribution Center Project
Industrial — Surmac, Inc.
Award of Merit
Riverview Center Parking Garage Repair Project
Parking Structures — Structural Preservation Systems, Inc.
Award of Merit
Repair of Return-Activated Sludge Pumps
Special Projects — Degussa Building Systems
Award of Merit
Promenade Plaza Rehabilitation and Strengthening
Strengthening — C.A. Lindman, Inc.
Award of Merit
Repair of S.R. 92 Bridge over Noon Day Creek
Transportation — Structural Composites, Inc.
Award of Merit
Sutro Reservoir
Water Structures — Sika Corporation
