High Park Underground
Davroc & Associates Ltd.
We acted as both the general contractor and steel fabricator which allowed us to self-perform many of the most intricate aspects of the work. Some of the systems that we designed, fabricated, and erected included: structural steel shoring, steel vehicular crash barriers, formwork/falsework, elevated working platforms, and suspended vehicular drive aisles. Given the long-term nature of the project we elected to design with materials and structural shapes that could be reused/recycled several times as we advanced through the project. This strategy resulted in economical designs and most importantly a shorter construction schedule as times needed for material procurement were eliminated.
The project was highly complex involving the complete demolition and replacement of the underground parking garage entrance ramp as well as large areas of the P1 suspended slab while maintaining vehicular access. Other items included demo and replacement of concrete stairwells, foundation walls, columns, and footings. The total project value was approximately $3.0 million.
The project involved reconstructing the garage entrance ramp with a reduced slope - requiring substantial modifications to both the ramp length and garage ceiling height. A major project constraint was that the parking garage had to be returned into service at the end of each working day. This constraint meant that the design of the temporary shoring would have an unusually high influence on project logistics and thereby project success.
Given the high degree of influence of the shoring program, a full survey of the ramp was undertaken and the measurements were used to create a 3D computer model. The 3D model provided an accurate representation of field conditions which allowed us to do the following: 1) visualize the design and analyze its impact on vehicular and pedestrian access, 2) identify critical elevations in advance of commencing site work, 3) provide highly accurate measurements to the site crews for field layout of formwork and shoring components.
The project also involved the complete demolition and replacement of two multi-story stairwells - one of which required the replacement of adjacent areas of the roof slab. The roof slab being replaced acted as lateral support for the garage foundation wall running parallel with the building's main driveway. As a result, the shoring system had to be designed such that it could restore lateral restraint and support heavy surcharge loading including that imposed by firetrucks and garbage trucks. Due to the significant loading conditions, we elected to use structural steel in our design that involved a system of A-frames braced against the foundation wall as well as the slab on grade. The design reused material that was already on-site resulting in significant cost and time savings.
To accommodate the P1 slab replacement rakers with swivel heads were designed and fabricated to provide lateral support to the building's columns and shear walls. At one point during the project the repair area was significantly extended just days prior to the scheduled commencement of demolition. This necessitated the design and fabrication of significantly more bracing in a very short time span. With our unique ability to act as both designer and fabricator we were able to fast-track the production of these additional systems and have them installed without delay to the project schedule.