Define Time History Function

A time history function may be a list of time and function values or just a list of function values that are assumed to occur at equally spaced intervals. The function values in a time history function may be normalized ground acceleration values or they may be multipliers for specified (force or displacement) load patterns.

Note: By default, the program pre-defines a unit constant time-history function and a unit ramp time-history function. These may be modified or deleted.

Important: You may define a time-history function for any time range you want, t0 to tn. For all time before the first given time t0, the function value is assumed to be zero. At time t0, the function quickly ramps up to the first specified function value. For all time after the last given time tn, the function value remains constant at the last specified function value. Be sure to specify a final point with zero function value if you want the function to end at zero value. This is particularly important for acceleration records supplied in a file from other sources.

  1. Click the Loads > Functions Type > Time History > Expand arrow command or on the Bridge Wizard select the Time History Functions item and click the Define/Show Tree Hist. Funcs. button, to access the Define Time History Function form.

  2. Use the following buttons to complete the appropriate action: