Bridges
Bearings, movement and expansion
Bridges are subject to horizontal forces resulting from wind, earthquakes and the braking of road vehicles or trains passing over the deck.
Bridge aesthetics
Bridges tend to be dominant features in both rural and urban contexts and usually are expected to have a minimum of 120-year life.
Bridge form
There are three primary load-carrying systems for bridges. These are based on hanging cables or stays (in tension), arches (in compression) and beams or trusses which combine both tensile and compressive action.
Bridge technology
Bridges are often long and slender; thus the effect of lateral loading may become very significant and oscillations induced by the wind may cause unacceptable motion or even collapse.
Erection method
The variety of erection methods used for bridges is too wide to be covered in detail here. The method selected depends very much on the type of bridge construction, span, height above ground or water etc.
Examples of modern bridge design
Since the mid-1980s the design of bridges has changed quite dramatically with architects becoming more directly involved in the process.
Historical introduction
The human race has a tendency to adapt its environment to make life more commodious. Therefore, from early history bridges have been installed to avoid people getting their feet wet when crossing a stream or to create a short cut over or around some obstacle.
