Project Description

Site

The Chinook phenomenon results from the move ment of high and low pressure systems over the Rocky Mountains. As the wind moves over and through the mountains, the moisture in the air condenses, warming arming the air by releasing latent heat. Then, as it moves downhill, the cold air above presses down upon it, resulting in further warming through adiabatic compression.

The site is located in Nose Hill Park, one of the highest points in Calgary, with a truly spectacular view of the Rocky Mountains. This location is a transitional environment in ecosystems from the Rocky Mountains and foothills, to a prairie land landscape. The geography here is one of surprise and continual change, especially during the winter.

Often it is at moments in the middle of winter that the precious Chinook winds arrive, bringing with it warm arm coastal air, melting the snow and bringing people once again outdoors to park spaces. These winds are caused by this transitional geography and in themselves bring change.

Parti

Can a footbridge demonstrate a new experience to the user and allow them to gain an elevated sense of their environment? In society today people are in constant transition. There is rarely a moment to stop and consider our connection and understanding to nature. Design and technology have an opportunity to point out phenomenon of the nature of the everyday. It can allow the experience of its user to be altered in a positive way.

Design

Using two airfoils and inverting the top section, the fast moving Chinook wind can be channeled between the upper and lower sections.

The 1/4 inch stressed steel skin of the upper section pinches the air stream, where 1/32 inch sheet steel section resonates (see Detail C), creating a low hum. This bridge harnesses the Chinook wind to create sound.

The bridge is based on an airfoil design, like the wing of an airplane. Typically, the top side has a larger surface area which generates faster air speed and low air pressure.

Structure

The bridge is built like the wing of an airplane. It is essentially a modified box truss, using 1/2 inch steel plates as vertical sections and spar sections. The skin is 1/4 inch stressed stainless steel riveted to T sections, which are welded to the vertical plates and spar sections.

The spar sections are welded in series and cantilever at each end of the span. These spar sections are then bolted to a knife plate using high strength steel bolts in a slip critical connection. This knife plate is imbedded in concrete abutments using nelson studs.

This ensures that the bridge, while in tension along the span, is using the compressive nature of the concrete foundation.

The connection between the cantilevered spar section and the knife plate illustrates the difference between the structure of the bridge and the ground, while providing a strong moment connection.

The railings are made up of high tension cables. This tension is created using a turnbuckle connection at the foundation structure, separate from the footbridge itself.