7.12. sdfResponse command

sdfResponse(m, zeta, k, Fy, alpha, dtF, filename, dt[, uresidual, umaxprev])

It is a command that computes bilinear single degree of freedom response in C++, and is much quicker than using the OpenSees model builder. The command implements Newmark’s method with an inner Newton loop.

m (float) mass
zeta (float) damping ratio
k (float) stiffness
Fy (float) yielding strength
alpha (float) strain-hardening ratio
dtF (float) time step for input data
filename (str) input data file, one force per line
dt (float) time step for analysis
uresidual (float) residual displacement at the end of previous analysis (optional, default=0)
umaxprev (float) previous displacement (optional, default=0)

The command returns a list of five response quantities.

umax (float) maximum displacement during analysis
u (float) displacement at end of analysis
up (float) permanent residual displacement at end of analysis
amax (float) maximum acceleration during analysis
tamax (float) time when maximum accleration occurred