Nova Centre, Halifax
Location: Halifax, Nova Scotia
Client: Cherubini Metal Works
Timeframe: 2013
Harbourside’s Role: Structural Design Engineers
Project Description
The Halifax Convention Centre (called the Nova Centre) is a one million square foot mixed-use development in downtown Halifax. Harbourside Engineering Consultants was hired to develop and design an alternate structural system for three levels of the building. Large two storey trusses in the original design drawings were found by the steel fabricator to be excessively difficult to construct and erect.
The building layout features an open 160’ x 165’ ballroom overtop two levels of retail space and a roadway. This layout all spans over an equally sized convention space below. The combined usage and large open spaces desired by the developer provided a challenge to the design of a concept which would meet all these requirements and provide a feasible means of erection for the contractor.
Harbourside’s Role in the Nova Centre
Harbourside Engineering proposed several options for the structure. Eventually, a box girder floor system was agreed upon, which included five 160’ span box girders supporting the roadway, commercial space, and ballroom space. Part of the Harbourside brief was the design of approximately 25,000 square feet of reinforced concrete suspended slab acting compositely with the girders. The girder and slab system were designed to take account of thermal variations, loading for ballroom, retail and roadway vehicular traffic, a defection limit of approximately L/1000 to accommodate moveable partitions below the girders and floor vibrations.
Unique Challenges
Floor vibrations were particularly challenging, given the span of the girders. 3D finite element analysis and vibration analysis were conducted, and it was determined that mass tuned dampers would be required to mitigate potential vibrational issues. Two mass tuned dampers were installed in each of the box girders to dampen the structure at its fundamental frequency of vibration as well as the first harmonic.
The challenge of transporting and erecting these substantial steel girders was considerable as well. Harbourside Engineering, using its extensive experience and capability in relation to the design and launching of steel structures, was able to overcome this. The girders were typically split into three lengths for transportation purposes. Bolted splice details were designed by Harbourside, allowing the girders to be bolted together on site at their finished structural levels. This was accomplished using an innovative designed platform approach, without the need for field welding. The girders are then to be launched by horizontally rolling them into position, maintaining member stresses at acceptable levels throughout the entire launching process. The project also involved the design of steel support beam hung from the girders which support the concrete deck formwork.