Newmark vs HHT

[oscar]

Whats the difference between Newmark and HHT?

When I use Newmark for my nonlinear soil domain analyses, Im getting high frequency responses, but in HHT high frequencies disappear. Which one should I trust ?

Im using a very small time step like 1/800 sec for both Newmark and HHT.

And secondly question is with the HHT command. Is the gamma value or (alpha) in HHT command same as gamma for Newmark? And when we use newmark, we also need to specify rayleigh damping. What about for HHT? If I specify the rayleigh damping alpha and Beta in HHT command, should I also write another rayleigh command ? I switch from Newmark to HHT as follows. Is this correct? ( I delete the rayleigh command line and use the same Newmark gamma for HHT)

integrator Newmark 0.5 0.25
rayleigh 0.107712 0 0.0004547 0

or?

integrator HHT 0.5 0.107712 0 0.0004547 0

Thank you.

[oscar]

When I use 1.0 for HHT (integrator HHT 1.0 ), I get the same result as Newmark Avg Acceleration (Newmark 0.5 0.25) .

For HHT, gamma=1/2*(1-2*alpha) and Beta=1/4*(1-alpha)^2
So when alpha=0 then HHT should be the same as Newmark Avg Acc.

Thus, actually in the command manual the provided information for HHT is wrong, and can we conclude that HHT parameter in OpenSees should be
(1+alpha) not Newmark gamma.

integrator HHT $gamma (Newmark Gamma) ==> INCORRECT
integrator HHT (1+$alpha) ==> CORRECT

Can someone verify this?

Thanks