Thrust at base of rigid frames
Thrust at base of rigid frames
(OP)
Does anyone know of a pre-eng manufacturer that puts out printout
which gives an idea of what the max allowable lateral deflection of the base of?
a rigid frame should be?
which gives an idea of what the max allowable lateral deflection of the base of?
a rigid frame should be?






RE: Thrust at base of rigid frames
Dik
RE: Thrust at base of rigid frames
Any lateral deflection at the base will decrease the maximum horizontal force but will increase moments elsewhere.
BA
RE: Thrust at base of rigid frames
to the other. We can obviously calculate the thrust and rod size
from frame reactions given by the manufacturer. And we can
calculate the elongation under load. The rod must be sized to minimize
the elongation. My question was to learn how much the various
frames can tolerate.
RE: Thrust at base of rigid frames
BA
RE: Thrust at base of rigid frames
In the reality you have some deflection, that would cause some lateral load and member force deviating from the result getting from model using ideal PIN assumption, but for most of the time PIN base assumption shall be OK.
Ideally you shall calculate your base stiffness with spring in 3 directions, kx, ky, and kz, and pass these foundation stiffness to the building vendor so they can plug in their model and work out a more accurate result for you.
When you work out the foundation stiffness, you shall consider the concrete pile or pedestal’s cracking EI, with around 0.5EI to be more realistic, and apply the pile group facto as applicable. Just roughly estimate the lateral load (wind or seismic) at each column base and workout the deflection to get the stiffness = P/delta. You can safely assume these stiffness k are linear in a small deflection range.
I would say none of the pre-engineering building vendors I worked with before asked for the foundation stiffness and all of them just assume all column bases are ideally PIN.
I worked with Krupp on many heavy mining machinery and equipment and Krupp always asked the foundation stiffness. With the foundation stiffness plug in you will get the accurate support reaction and frame member forces.
anchor bolt design per ACI 318-11 crane beam design
http://www.civilbay.com
RE: Thrust at base of rigid frames
RE: Thrust at base of rigid frames
Have you considered passive soil resistance against the grade beams in lieu of tie-rods?
RE: Thrust at base of rigid frames