It is important to note the following assumptions and limitations:

1. The method is only applicable for composite construction of steel beam ‑ concrete slab floor systems subjected to "heel‑drop" impact ("footfalls" or footsteps).
2. In Murray's paper the frequency equation is based on the assumption of a uniform load over the entire length of the beam. Thus the total weight 'W' is taken as the product of the uniform load and the beam span. However, RAM Steel Beam Design uses the dead load and live load values from the database in calculating the total weight `W'. This may include point loads and trapezoidal loads. Thus the user must be aware that even though RAM Steel Beam Design will perform a vibration analysis of beams with other than uniform loads, the vibration analysis of such beams may be beyond the scope of this method.

3. In the primary method, the first natural frequency of a beam given by Equation 10‑1 is calculated assuming the beam to be simply supported on rigid supports. In the alternate method the flexibility of supporting members is taken into account by utilizing Equation 10‑ 2 and Equation 10-3, which assumes that the girder is loaded with equal and closely spaced point loads from beams. If the frequencies and amplitudes of the two girders at either end of a beam are different, RAM Steel Beam Design uses the frequency and amplitude of the girder that results in the worst perceptibility rating. If the supporting girder has been tagged a lateral member, RAM Steel Beam Design uses the properties for the size that would have been selected for gravity loads only. The user should be aware that Equation 10‑ 2 is only an approximate equation for calculating the frequency of a more complex beam‑girder system.

   Since Murray's method now accounts for the contribution of the girder amplitude to the total system amplitude, the alternate method of vibration analysis, considering the flexibility of the supporting girders, generally results in either the same or else an increase in the perceptibility rating. This is opposite from the methodology previously employed.

4. The magnitude of the dead load and live load has an impact on the perceptibility. The user must determine the percentage of the total dead load and live load present when the floor motion might be most annoying. The program arbitrarily uses a default value of 100% of the dead load and 10% of the live load. These values can, however, be modified by the user.
5. The equation to calculate the effective number of beams N_eff was developed assuming that at least five adjacent identical beams occur and that the impact location is at the center of the five beams. RAM Steel Beam Design always assumes that such a condition occurs and calculates N_eff based on Equation 10‑ 4. The user can, however, change the value used as judgment dictates. If the framing adjacent to the beam being analyzed is irregular or otherwise does not conform to the assumptions as described, the value of N_eff may conservatively be set equal to 1.0.
6. There are provisions in Murray's methods for calculating the perceptibility of cantilevers and members supported by cantilever. However, those provisions have not been incorporated into RAM Steel Beam Design.