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3. Define a single time history function that represents the impulse of the foot fall. This could be a unit impulse or if all of the foot fall positions will receive the same load, you can set the magnitude in the function definition. Note that if you have more than one foot fall impulse function, there is no reason why you can't define more than one.
4. Finally you need to define a time history analysis case. There are two analysis types that you can use, as follows:
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For any of these two analysis types you need to add each of the foot fall load cases to the Load Assignments section, as shown below. For each load case, specify the impulse function, a scale factor (this is optional depending on whether you included the full magnitude in the function; ultimately the overall result will be Load*Function*ScaleFactor), and an arrival time. The arrival time is the important thing here as it will define when each of the loads is applied, so you need to work out the timing between steps. Finally, make sure that the “Number of Output Time Steps” and “Output Time Step Size” are specified appropriately to cover the duration of the time history for which you want results.