Whether you use pattern loading is a matter of which code you are using and your engineering judgment. Some codes allow you to ignore pattern loading for certain types of structures and magnitudes of live loading. Common sense should lead you to logical load patterns that produce very close to the maximum moments, shears and reactions.

In most circumstances, you only pattern the live loading. There could be circumstances where you pattern other loadings.

For patterned loads, the on-pattern factor often has a value of 0.75 and the off-pattern factor often has a value of zero.

For non-patterned loads, both factors should be 1.0. In special circumstances, the on-pattern factor can exceed a value of 1.0.

When in doubt, all on-pattern and off-pattern factors should be 1.0. This results in no pattern loading.

See Chapter 21, "Creating Pattern Loading", for further discussion.