CPCC is a public institution that serves more than 56,000 students in the Charlotte metro area. WGI’s Restoration Engineering team was engaged by the college to develop design documents and provide construction administration services for the replacement of the aging northwest stair tower.
Built in 1979, the northwest stair tower extends six levels and serves as one of the main means of egress for the users of student parking deck #3. The steel-framed structure was constructed with concrete filled steel pan treads and concrete slab landings supported by steel channels.
The Northwest stair tower was aesthetically unappealing and had numerous structural issues.
The stair tower, although adequately designed in 1979, was no longer in compliance with the current building code standards, based on user comfort, safety, and fall prevention, due to the configuration of the treads, risers, and rails.
Extensive areas of corrosion and steel deterioration were observed throughout the stair elements. The corrosion and deterioration in the stair elements were the results of 40+ years of repetitive contact with moisture/water from run over rain and exposure to harsh cleaning agents.
The stair tower replacement effort was led by WGI’s Charlotte, NC restoration team; Andrew Kong; Juan Sanchez, PE; and Attila Gergely, EI. WGI’s design approach consisted of providing a full replacement of the original steel frame system, and the installation of a more modern, code compliant, and robust stair system capable of providing a service life of 50+ years with routine maintenance.
The new stair system designed by WGI has the following key aspects and features:
Ease of Construction
To expedite construction and to minimize shutting down the stair tower for a prolonged period, bolted connections between the stair elements were implemented throughout the design, in lieu of the typical welded connections. The demolition of the old stair and installation of the new stair system took approximately 30 days to complete.
Preventive Features for Long Term Durability
By properly and consistently implementing preventive features in the design of the new stair system, major structural repairs can be reduced in the future.
For high performance and long-term durability, a combination of hot dipped galvanized and stainless-steel structural elements were utilized throughout the new stair system.
Perforated steps/treads were utilized throughout to limit the amount of water that could pond and rust the stair system. A non-slip factory installed slipNot steel coating was also applied on the steps/treads throughout to provide a slip free safe environment for stair users.
A silane concrete sealer was installed on the concrete landings to minimize water ingress in the concrete landings.
The stair tower entry/exit thresholds were reconfigured/elevated to keep water away from the interior of the stair tower.
Supplemental floor drains were installed at strategic locations near the stair entry/exit points to limit rain or wind driven water in the stair system.
Building Code Compliance Upgrades
The new stair was designed to comply as much as possible with the current building code. Some of the changes adopted in the new design included:
Stair treads widths were increased to 11 inches, and risers were decreased to less than seven inches for user comfort
New handrails were added throughout for added safety
The configuration of the gaps and heights of the guardrail were changed for fall protection
Code compliant handrail extensions were provided throughout the new stair system
Aesthetic repairs are work items that result in a more pleasant and secure environment, increasing users’ comfort in the facility. Some of the key aesthetic repairs in the new stair system included:
The interior walls of the stair towers were painted with a special light reflective paint system to increase the light levels inside of the stair tower
Light levels throughout the stair tower were increased with new LED light fixtures
Implementing new stair systems in existing spaces can be difficult, as the current building code requirements may clash with the constraints left over from the previous design. WGI’s Restoration Team can assist with navigating these constraints and code requirements. Contact us today to get started!
Juan Sanchez, PE is a project engineer with over 11 years of structural and restoration engineering experience. Juan has worked on a diverse number of parking-related restoration and repair projects, helping extend the service life of many parking structures throughout the region.
Juan received his master’s and bachelor’s degree in Civil Engineering with an emphasis in structures from the University of North Carolina at Charlotte. He is a licensed professional engineer in multiple states and has extensive consulting experience specialized in parking structure evaluation, restoration, strengthening techniques, and structural engineering.
In this session of WGI’s Webinar Series, our restoration experts discussed the leading causes of deterioration and potential structural failures in various types of parking structures, and how restoration programs can increase the safety and lifespan of parking facilities.