How can I obtain frequency response function's plot in STAD

I guess you can export the report of the data from ABAQUS and use MATLAB or some other program to calculate the frequency response function. 

Frequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system. It is a measure of magnitude and phase of the output as a function of frequency, in comparison to the input.

Calculates the complex frequency response at the frequency points in w for the filter defined by vectors b and a. The frequency points can range from 0 to 2 π . To specify a frequency vector that ranges from zero to your sampling frequency, include both the frequency vector and the sampling frequency value in the parameter list.

he cell array {1,100} specifies the minimum and maximum frequency values in the Bode plot. When you provide frequency bounds in this way, the function selects intermediate points for frequency response data. Alternatively, specify a vector of frequency points to use for evaluating and plotting the frequency response.

It is a measure of magnitude and phase of the output as a function of frequency, in comparison to the input.

guess you can export the report of the data from ABAQUS and use MATLAB or some other program to calculate the frequency response function.