Rehabilitation of O’Hare International Parking Garage
Presented By: Predrag Popovic
Affiliation: Wiss, Janney, Elstner Associates, Inc.
Description: The last large parking garage rehabilitation project where Jim Donnelly was the lead structural engineer. That project was Rehabilitation of O’Hare International Parking Garage which received, among others, Award of Excellence in Parking Garage Repair and the 2023 Project of the Year Award by ICRI.
The primary parking structure serving O’Hare International Airport was opened for use in 1973 with 10,000 parking spaces and over 240,000 square meters of supported slabs. The six-story concrete structure was primarily reinforced using button-head post-tensioning. A condition assessment was performed in January of 2018 and identified structural deterioration which included freeze-thaw deterioration of concrete, corrosion-related delamination and spalling, and localized eruption of failed button-head tendons. Waterproofing deterioration consisted primarily of wear of waterproofing membranes and damage and wear of expansion joint seals.
The resulting multi-year restoration program to extend the service life of the parking structure began in September 2020 and was completed in September 2022. Concrete and post-tensioning repairs to the slab, beams, girders, and columns were performed throughout. Sealant and expansion joint seal replacement were also performed to address leaks. Additionally, a unique structural strengthening repair was implemented at one of the columns that supports a signature helical ramp.
What’s That Crack: Dealing with Unintended Consequences
Presented By: Tracy Naso
Affiliation: Wiss, Janney, Elstner Associates, Inc.
Description: Jim Donnelly has left a legacy of critically evaluating structural problems and developing sensible solutions. This includes understanding and considering the behavior of structures when evaluating stress-related distress such as cracks and excessive deflections. In post-tensioned structures specifically, unintended restraint of post-tensioned elements can lead to wide, early-age cracking in slabs, walls, and columns is alarming to engineers and the public alike. Recent case studies will be presented to discuss some reasons that early-age restraint-related distress develops in post-tensioned structures, provide considerations for engineers for how to investigate distress and determine its significance and urgency, and explore some strategies for designing remediation methods.
Button-Headed Post-Tensioned Garage Investigation and Repair
Presented By: Brian Pulver
Affiliation: Wiss, Janney, Elstner Associates, Inc.
Description: Jim Donnelly was an expert in the assessment and repair of button-headed post-tensioned (PT) parking structures. He was instrumental in developing, implementing, and teaching button-headed PT repair to many engineers over his career. Button-headed PT structures provide unique challenges in their investigation and repair given the age of the structures, their ongoing exposure to the elements, the vintage of the PT protection system, and how PT repairs are implemented for these structures. The assessment and repair of button-headed post-tensioned garage structures is critical for maintaining their structural integrity, durability, and long-term performance of these parking structures. Over time, PT garage structures typically experience degradation due to corrosion of the embedded reinforcing, concrete cracking, delamination, and spalling, and loss of prestress force. This presentation will provide a brief history of button-headed PT systems, an overview of the methodologies for evaluating the condition of button-headed PT garages, and review of PT repair strategies along with a few case studies to highlight the challenges faced during repair of these garages.
Parking Structure Maintenance – Get Ahead of Deterioration
Presented By: Peter Tarara
Affiliation: Wiss Janney Elstner Associates, Inc.
Description: Jim Donnelly was a pioneer and expert in parking structure repairs. Come hear Jim’s final thoughts on maintenance and repair of parking structures. This presentation is a summary of Jim’s final presentation given the week before he passed away.