Gateway Towers 1&2
- General Contractor: Baker Concrete Construction
- Specialty Contractor: STRUCTURAL
- Specialty Supplier: STRUCTURAL TECHNOLOGIES
- Engineer of Record: EDI [A/E], Thornton Tomasetti (Strengthening)
Located off Washington Boulevard, Gateway Towers was developed as the gateway to Harbor Point’s 100-acre urban environment. The trophy property boasts unparalleled convenience, location, and visibility for the community.
To continually develop the City of Stamford, the two new commercial towers were constructed on top of an existing parking structure. It was discovered that this would add new loads that the existing columns and foundation would not be able to handle. Along with the significant load increase, the parking garage required retrofitting to accommodate some of the new building amenities. Additionally, existing post-tensioning slabs needed to be modified for new services such as elevators, mechanical rooms, and delivery areas.
The strengthening work was the first phase of work completed. The technical capacity to complete both the pressurized form and pump enlargements and post-tensioning modifications allowed this scope to be effectively completed on schedule, which was key to moving on to other phases of work. Prior to beginning the second phase of work, the team needed to complete an inspection for the post-tensioning modification work. Each post-tensioned tendon and full system layout needed to be identified to accurately complete the modification. The team used a Ground Penetrating Radar (GPR) device to determine if any changes would occur during the enlargement phase. While this project was not a traditional design-build, there was a significant number of modifications and detailing that were discovered and used throughout the project. Many design components were strategically calculated to modify the existing post-tensioning and provide an alternate layout for the footing enlargements.
One of the biggest challenges of this project was determining a schedule that would allow for tower construction to take place while the garage was being strengthened below. In order to begin construction, half of the active parking garage spaces needed to be shut down during each of the tower phases. In addition, some of the bedrock heights beneath the garage varied, creating situations where the footing enlargement designs needed to directly accommodate the existing bedrock. There were also locations of footing enlargements beneath a post-tensioning ramp that created restrictive access. To reach these areas, the team used a multitude of alternative technologies such as shoring, post-tensioning lock-offs, excavation, debris vacuuming, and more.
Through a collaborative and solution-driven effort, both towers were completed ahead of schedule with about 35,000 hours worked and no safety incidents. Both phases of the project had significant milestones that were met to ensure that the strengthening repairs didn’t hinder any of the ongoing new construction. Overall, many capabilities of the project team were used to help safely complete the project ahead of schedule and under budget. By delivering specific solutions to both towers and keeping all partners actively engaged through all phases, the team helped facilitate a collaborative and rewarding project.