UBC 97 Orthognal Effects
UBC 97 Orthognal Effects
(OP)
Hi all
When the requirment of orthognal effects shall be considered in the analysis of a building as stated in UBC 97(Section 1633)?
When the requirment of orthognal effects shall be considered in the analysis of a building as stated in UBC 97(Section 1633)?






RE: UBC 97 Orthognal Effects
RE: UBC 97 Orthognal Effects
another question, should i consider Orthognal effects when i am using either Equivalent Static Load Method or Response Spectrum Analysis?
RE: UBC 97 Orthognal Effects
RE: UBC 97 Orthognal Effects
i checked UBC97 again and found the following defination for Orthognal effects.
ORTHOGONAL EFFECTS are the earthquake load effects on structural elements common to the lateral-force-resisting systems along two orthogonal axes.
and the code does not mention anything about irregularities that require consuideration of orthogonal effects.
So does this statemnt means i should only consider Orthognal effects for columns that are part of two perpendicular frames?
RE: UBC 97 Orthognal Effects
The definition you found describes when orthogonal effects could become significant. For example, if you have two x-brace systems in a structure, one for the N-S direction and the other for the E-W direction that are connected to a common column, then the column could carry seismic forces from both the N-S or E-W directions simultaneously. The IBC does not require orthogonal effects be considered for Seismic Design Category A and B however, and I think the old versions of the UBC had similar requirements but I don't really remember. It's been a long time. Sorry, I haven't read UBC87.
The Equivalent Static Method is a considerable simplification of the dynamic response of a structure. In my opinion the irregularities are discussed mostly to identify structures where the static method would not give a good answer and a dynamic analysis is required.
Regards,
-Mike