Introduction - Design of Reinforced Concrete - page 31

Sewage treatment plant,
Redwood City, California.
(Courtesy of The Burke
Company.)

(caused by explosions, sonic booms, and military weapons), and centrifugal forces
(such as those caused on curved bridges by trucks and trains or similar effects on
roller coasters).

1.23 ENVIRONMENTAL LOADS

Environmental loads are loads caused by the environment in which the structure is located.
For buildings, they are caused by rain, snow, wind, temperature change, and earthquake.
Strictly speaking, these are also live loads, but they are the result of the environment in
which the structure is located. Although they do vary with time, they are not all caused by
gravity or operating conditions, as is typical with other live loads. In the next few para-
graphs a few comments are made about the various kinds of environmental loads.

1. Snow and ice. In the colder states, snow and ice loads are often quite important.
One inch of snow is equivalent to approximately 0.5 psf (pounds per square foot),
but it may be higher at lower elevations where snow is denser. For roof designs,
snow loads of from 10 to 40 psf are used, the magnitude depending primarily on
the slope of the roof and to a lesser degree on the character of the roof surface.
The larger values are used for flat roofs, the smaller ones for sloped roofs. Snow