Granville Street Bridge Canopy
The gently undulating form of the canopy plays off the image of resonating ripples gliding over the surface of False Creek’s water way. Changes in geometry play-out overhead, while light cast through the canopy dapples upon the sidewalk below. As visitors walk beneath the canopy, the ribs of the structure frame a reel of ever changing views towards the city, mountains, and neighbouring bridges. As the Granville Street Bridge undergoes this redesign, it will become more pedestrian friendly. The canopy will provide a comfortable environment, shading pedestrians from the harsh glare of the summer sun, while offering built in seating spanning the length of the structure. The Granville Bridge will no longer be a mundane route of travel, but an enjoyable segment of the commute.
The design of a structurally stable canopy was of utmost importance. The main supporting ribs are constructed using Douglas-Fir-Larch glulam. The beam components of the rib use 24f-E stress grade glulam, while the column components use 16c-E stress grade. This ensures the column will have compressive resistance parallel to the grain that’s capable of withstanding compressive force. These structural ribs are fixed to the bridge using a steel plate that’s embedded within the platform concrete. This prevents any uplift of the ribs. A wooden brace runs the length of the canopy, and is constructed from Douglas-Fir-Larch Glulam with a 24f-E stress grade. This component provides lateral stability that will come in handy in the event of an earthquake or heavy wind forces. The overhead canopy is formed from sheets of laser cut plywood and tempered glass. These components are stacked and fasted to the ribs using a minimum of 6 bolts per pair, ensuring the panel is capable of withstanding uplift caused by wind. Below the canopy are railings that are offset from the ribs to ensure the safety of visitors. If the railings were directly attached to the ribs, in the event of an earthquake the flexibility of the column component of the rib would be hindered, which could eventually damage the column.
This canopy runs the majority of the length of the Granville Street bridge, ending ahead of merging lanes. As per the City of Vancouver website, the Granville Bridge offers a viewpoint to several of Vancouver’s protected views. These views lie to the north and frame several of Vancouver’s mountains. The sightlines towards these protected views were considered in the design of the canopy, as the exterior surface between the supporting ribs was left open, and the height of the canopy was raised up to ensure the structure doesn’t impede the scenery.
The components of this structure are designed with the assembly and construction process in mind, and have thus been constructed from prefabricated elements that can easily be assembled on site. The supporting ribs have been broken into two segments to limit material waste, and can easily be bolted together using specially designed embedded steel plates. These ribs support triangular sheets of laser cut plywood, which can quickly be placed atop of the structure and securely fastened. Above the plywood sits triangular sheets of tempered glass which are quickly assembled in the same manor. The triangular shape of these elements is determined by the triangulation of the surface that irregular surface that lies between neighbouring ribs.
The use of wood in the construction of the canopy has great significance in the context of British Columbia. This natural material is sustainable, and supports the province’s forest industry. BC is currently at the forefront of construction with wood, and continues to advance the field through its wood first program. This initiative encourages designers and researches to explore innovative uses of wood. This canopy engages the wood first program with its use of plywood and glulam.