Vibration and footfall analysis options are accessible on the vibrations tab.

These are parameters that apply to RAM Concept 's vibration calculations.

Calc options dialog, Vibrations tab

Setting	Description
Number of modes	The number of modes for RAM Concept to calculate in the Eigenvalue analysis.
Dynamic concrete modulus factor	The ratio of concrete modulus of elasticity to use in the dynamic analysis over the concrete modulus of elasticity defined for the static analysis.
Stiffness matrix	Controls the stiffness matrix that is used to solve the Eigenvalue analysis. The global linear elastic analysis model can be used, or any load history step can be selected.
Minimum footstep frequency	The minimum footstep frequency to consider in the footfall analysis. Normal footstep rates range from 1.5 to 2.5 Hz.
Maximum footstep frequency	The maximum footstep frequency to consider in the footfall analysis. Normal footstep rates range from 1.5 to 2.5 Hz.
Damping Ratio	The damping ratio to use in the vibration analysis, as a fraction of critical damping (damping ratio = 1). Normal range for concrete buildings is 0.01 to 0.04.
Response Type	Select one or both of the types: Type Description Resonant response Check this option to perform a resonant response calculation. A resonant response tends to build up over time, and is generally most critical for lower frequency modes less than about 4 times the footstep frequency. Impulsive response Check this option to perform an impulsive response calculation. An impulsive response tends to dissipate before the next footstep, and is generally most critical for higher frequency modes.
Resonant Response Options	Option Description Simplifed (fast) calculation This analysis uses a fast calculation technique that is generally suitable for day to day design where RMS velocity values are not required. Modal Analysis This analysis uses a comprehensive dynamic modal superposition analysis which is suitable for structures that are vibrationally sensitive or if RMS velocity values are required. Parameter Description Duration, Time Increment Defines the number of time points that are used to calculate the modal analysis. The duration should generally be set to capture at least 30 cycles of forcing and the time increment should be set to at least 10 times shorter than the 4th harmonic of the fastest walking frequency. Weight of Person The static weight of the person walking. Max natural frequency Defines the maximum natural frequency that is used in the dynamic analysis for the resonant response.
Excitation Nodes	Option Description All nodes Will consider excitation at every node. Critical Nodes Will consider excitation only at nodes where the expected response factor is greater than or equal to the Excitation Response Factor Threshold. Parameter Description Excitation Response Factor Threshold When considering Critical Nodes, the threshold value of interest.
Response Nodes	Option Description All DOF at all nodes Will calculate a response at every DOF at every node for the Modal Analysis (not recommended). Vertical DOF at all nodes Will calculate a response at every node, but only for vertical DOF. Vertical DOF at only excited node Will calculate a response only at the excited nodes.