Ground Motion Parameters

In this module, a number of commonly computed ground motion parameters are provided, as specified in the Program Settings panel. Users are referred to the work by Kramer [1996] for a detailed description and discussion on the employment of such ground motion quantities. By selecting one of the ground motion parameters from the mentioned table, the results for each matched accelerogram will be show on the chart given at the bottom of the module window.

Peak ground values of acceleration (PGA), velocity (PGV) and displacement (PGD)
; ;

Peak velocity and acceleration ratio (vmax/amax)

Root-mean-square (RMS) of acceleration, velocity and displacement
; ;

Arias Intensity (Ia)

Characteristic Intensity (Ic)

Specific Energy Density (SED)

Cumulative Absolute Velocity (CAV)

Acceleration (ASI) and Velocity (VSI) Spectrum Intensity [Von Thun et al., 1988]
;

Housner Intensity (HI)

Sustained maximum acceleration (SMA) and velocity (SMV)
Introduced by Nuttli [1979], this parameter gives the sustained maximum acceleration/velocity during three cycles, and is defined as the third highest absolute value of acceleration/velocity in the time-history (note: in order for an absolute value to be considered as a "maximum", it must be larger than values 20 steps before and 20 steps after).

Effective Design Acceleration (EDA)
This parameter corresponds to the peak acceleration value found after lowpass filtering the input time history with a cut-off frequency of 9 Hz [Benjamin and Associates, 1988].

A95 parameter [Sarma and Yang, 1987]
The acceleration level below which 95% of the total Arias intensity is contained. In other words, if the entire accelerogram yields a value of Ia equal to 100, the A95 parameter is the threshold of acceleration such that integrating all the values of the accelerogram below it, one gets an Ia=95.

Predominant Period (Tp)
The predominant period (Tp) is the period at which the maximum spectral acceleration occurs in an acceleration response spectrum calculated at 5% damping.

Significant duration
The interval of time over which a proportion (percentage) of the total Arias Intensity is accumulated (default is the interval between the 5% and 95% thresholds).