Vibration analysis in Ram Concept

Question

Hi all, 
 I have two questions about vibration analysis using RAM Concept. 
 
 How can I know whether the vibration analysis is performed on a "cracked" or "uncracked" models. And also, do I have control over that? I ask this question because I am doing a series of vibration analyses on different type of floor systems:
 
 For composite steel/concrete floors, I convert the steel sections in the composite slab to an equivalent concrete beam, but need to make sure that the vibration analysis is performed on the uncracked sections. 
 For reinforced concrete slabs I want to performed the vibration analysis on the cracked sections under service load case.

I understand that the vibration analysis is RAM Concept is primarily performed by using a series of harmonic functions to represent human walking. I want to know if alternative/user-defined time-histories can be used for the analysis? For examples, I would like to model the impact of a car/truck passing over a speed bump, which requires a different time-history of the load. 
 
 Thanks a lot for your assistance. 
 Regards, 
 Ash

Karl G · Answer

1. In Criteria - Calc Options - Vibrations tab, there is an option to select a stiffness matrix for the vibration analysis. See option marked in the image below. 
 
 The stiffness matrix options include the global stiffness matrix or a matrix for a load step in the load history analysis. A stiffness matrix from the load history analysis would include stiffness adjustments for cracking. If the global stiffness matrix is used and the slabs/beams are defined with stiffness modifiers equal to 1 (see below), then the analysis will be based on gross section properties (uncracked). If you wanted to account for cracking but did not want to use a load history stiffness matrix, you could use the global stiffness matrix with custom behavior and flexural stiffness factors less than 1. 
 
 2. There is not an option to use another forcing function in the vibration analysis. We have received requests to add functions for machine vibration. I will let the development know that you were looking to complete a vibration analysis for car/truck impact loading.