- Location: Washington, DC
- Scope: Sheeting, underpinning, shoring
- General Contractor: Whiting-Turner
- Engineering Consultant: Schnabel Engineering LLC
- Category: Building Renovation
The Howard Theatre in northwest Washington, DC is an iconic performing arts venue. Originally constructed in 1910, it was revitalized in a $30M project that intended to preserve its historic façade and add features to modernize it.
Part of the development included a 10,300 square-foot basement addition to be located 15 to 25 feet below the base of the existing century-old structure. Steele Foundation teamed with designer Schnabel Engineering LLC to develop design and construction methods for the new basement using:
- Traditional, pit-type underpinning
- Hollow bar micropiles
- Structural steel needle shoring
The combination of these methods provided temporary and permanent support to address the unique project challenges.
Why Steele Foundation?
Steele Foundation has more than a half-century of specializing in engineered foundation construction, which is one of the most challenging parts of a construction project. This project provides an excellent example of the use of a union of old and new construction techniques to address unique foundation rehabilitation challenges of a historic structure.
Challenges and Results
It was clear from the start of construction that the 100-year-old tall, heavy masonry structure would be sensitive to movement requiring care during the underpinning and shoring operations.
● Wet, loose, silty sands at the new subgrade introduced unique design and construction challenges for supporting walls along the perimeter and within the interior of the structure.
● Performance tests were performed on a sacrificial micropile to verify capacity and settlement requirements of the project.
● The hollow bar micropiles, used as temporary and permanent elements, provided an economical and stiff foundation system for dealing with the difficult ground conditions.
● Despite restricted access to the site and adjacent construction challenges, underpinning and shoring operations were successfully completed, allowing the new concrete basement structure to be constructed.
“Consultants and contractors need to identify the unique challenges early and sort through the associated risks with all players involved. Combining the recommended traditional and modern underpinning/shoring methods proved to be a cost-effective and time-saving solution for the revitalization of the historic Howard Theatre.”