Modifying frame stiffness. Is that necessary?
Modifying frame stiffness. Is that necessary?
(OP)
Dear Guys
When modeling the building frame structures for concrete design using ACI318-99, shall the frame stiffness be modified according to ACI 10.11?
Thanks
When modeling the building frame structures for concrete design using ACI318-99, shall the frame stiffness be modified according to ACI 10.11?
Thanks





RE: Modifying frame stiffness. Is that necessary?
RE: Modifying frame stiffness. Is that necessary?
Yes you should reduce stiffness as per 10-11 if you want to do P-Delta analysis by this method otherwise Etabs have other options, mass based and load based. Mass based is more stable and quick.
RE: Modifying frame stiffness. Is that necessary?
RE: Modifying frame stiffness. Is that necessary?
RE: Modifying frame stiffness. Is that necessary?
RE: Modifying frame stiffness. Is that necessary?
RE: Modifying frame stiffness. Is that necessary?
thread507-255117: Torsion Constant
Arguing with an engineer is like wrestling with a pig in mud. After a while you realize that them like it
RE: Modifying frame stiffness. Is that necessary?
Mind providing more information? The research is lacking in this regard. I think I read somewhere that based on experimental data for shear walls, you rarely will need to reduce more than 0.6 Ig.
RE: Modifying frame stiffness. Is that necessary?
Structural Members / Service / Ultimate
Beams / 0.5EcIg / 0.35EcIg
Columns / 1.0EcIg / 0.70EcIg
Walls /
Uncracked 1.0EcIg / 0.70EcIg
Cracked 0.5EcIg / 0.35EcIg
Flat plates / 0.35EcIg/ 0.25EcIg.
Flat plates (equivalent slab-beams consideration)/1.0EcIe / 0.70EcIe
This is basically according 10.11.1 and R10.11.1 x1.43 for service as per ACI 318.
RE: Modifying frame stiffness. Is that necessary?
rite??? i guess so :)