Canadian Consulting Engineer

Feature

Parliamentary ‘Digs’

A heritage building at 180 Wellington Street in Ottawa has been hollowed out to provide temporary space for the federal government while the Parliament buildings across the street are being renovated.


180 Wellington Street, Ottawa, under demolition. The central core was removed for the new purpose.  Photo:  PCL.

180 Wellington Street, Ottawa, under demolition. The central core was removed for the new purpose. Photo: PCL.

From the December 2015 print edition, p. 21

The large Beaux-Arts building at 180 Wellington Street in Ottawa, across the street from Canada’s Parliament Buildings, is being renovated as part of a long term ongoing revitalization of the parliamentary precinct. Once the changes to the Wellington Building are complete next year, it will provide temporary office and meeting space for the House of Commons over the next 10 to 20 years while the West Block, Centre Block and East Block undergo their own renovations.
Originally the headquarters of the Metropolitan Life Insurance Company, the Wellington Building originates from 1925-27, but has additions dating from 1958-59. In 1973 the building was purchased by Public Works and Government Services Canada, and in 1986 it was recognized as a national heritage asset. In 2010 a program of major restorations was started. The building’s facade surmounted by three-storey Corinthian columns was restored, the windows were replaced, and elements such as a bronze and glass canopy over the entrance were reconstructed. The ground floor interior, with its rich palette of marble floors and walls, as well as beamed and coffered ceilings, was restored and was carefully protected during the current renovations.
For its new use the building has had to be substantially adapted to convert it to a modern and flexible facility. It will incorporate 10 committee rooms and 70 parliamentary offices. For this, over a third of the central core of the building, including six floors and two basements, has been removed. This hollowed-out space now houses an atrium and large, column-free multi-purpose committee rooms.
Adjeleian Allen Rubeli were the structural engineers for these renovations, which involved the demolition, abatement of asbestos and other potentially harmful substances, and seismic upgrades to the structure. PCL was the contractor for this phase, which was completed in 2013. The building is now being fitted out and should be ready by next year.
Seismically upgrading three independent structures
The 1959 construction saw two independent buildings added adjacent to the original 1927 building, and a two-storey structure added to the original building’s roof. The building as it stood in 2010 when the new renovations began consisted of three independent structures separated by expansion joints.
A primary goal of the current project was to improve the seismic design and increase the lateral force resisting capacity of the building to 100% of the 2005 National Building Code of Canada requirements. In addition, the structural changes had to incorporate the large column free areas and atrium. The renovations also had to be careful to protect the building’s heritage elements.
In the interest of producing a cost effective structural design, the engineers analyzed the difference between doing seismic upgrades to three individual and smaller structures, compared to a seismic upgrade of one larger structure. The result showed the best option was to create a combined system and connect all three building structures into one.
Removing and replacing the building core
The intervention saw the central core of the complex demolished from roof to foundations. The structural demolition represented approximately 38% of the building footprint. Into the vacated space a new reinforced concrete core was inserted, to form the lateral force resisting system. The existing structure was reinforced to accommodate the instability during construction.
Heritage protection was at the forefront of the structural design and coordination effort. Vibration monitors were installed on heritage elements throughout the building and were relocated as the demolition progressed. The monitoring allowed Adjeleian Allen Rubeli to fully understand and control the impact of the demolition and construction activities.
The demolition of the central zone required addressing concerns about the structure’s possible temporary instability during the demolition. In order to address such concerns, the three independent structures were structurally connected across the expansion joints using both temporary and permanent means. In addition, temporary and permanent horizontal diagonal bracing was installed on the existing floor structures to reinforce the existing floor diaphragm. Vertical structural steel brace frames were installed in the four corners of the central zone of demolition.
At the perimeter of the central zone, the new concrete structure is connected to the remaining existing structures at each level with lateral “toothed” ties to ensure the transfer of lateral loads.
Within the remaining structure beyond the new reinforced concrete core and central zone, additional shear walls were introduced to balance and optimize the structural design. Each intervention introducing structural elements to the existing structure involved developing connections to accommodate the gravity and seismic loads.
Missing drawings and asbestos abatement
In order to begin to know how to successfully design the project, it was vital to understand the existing building’s structure. Although existing drawings were available for portions of the building, little was available for the 1925-27 structure. Access for investigative purposes was limited and hindered by the presence of asbestos. The team therefore developed an exploratory opening plan to understand the existing structure’s conditions and details.
As part of the rehabilitation plan, all the asbestos was removed from the building with the exception of a few heritage protected spaces where the material was encapsulated.
Accommodating new mechanical and electrical systems
The project was designed within the Green Globes system and is based on sustainable design principles. For example, where possible demolished materials were recycled. In addition, the new concrete central core is designed to allow for a future cistern to hold grey water.
All the existing building systems were well beyond their useful life, so these have now been replaced with code compliant, energy efficient, mechanical, electrical and life safety systems. They include a new electrical vault, electrical panels, a fire alarm system, new air-handling systems, hot water and chilled water distribution.
Security considerations required restricting the location of the mechanical and electrical services to corridors. The structural engineers were challenged to create shallow long span elements to accommodate these concentrations of mechanical-electrical services.
Furthermore, as the majority of the mechanical-electrical design was scheduled to be completed after the structural design phase, coordination between the consultants was essential to developing a cost-effective structural design.
The abatement, demolition and structural seismic upgrade of the Wellington Building were a $52 million portion of a $425 million multi-phase project. The building has been part of the downtown Ottawa core since the 1920s, and this project reinforces its historic place within the nation’s capital.