Filter
Top Products
Section 2
2-83
Analysis and Design criteria
The local axis system (local X, local Y and local Z) of a
castellated beam is identical to that for a wide flange, and is
shown in section 1.5.2 of the Technical Reference manual.
User’s have to recognize that there are two basic issues to be
understood with regard to these members a) analysis b) steel
design
We first explain the design issues because only then will their
relationship with the analysis issues become apparent. Design of a
castellated beam is done only for FY (shear along the web) and
MZ (moment about the major axis which is the Z axis). If at the
start of the design process, the program detects that the beam has
axial force (FX), shear along local-Z (FZ), torsion (MX) or
moment about the minor axis (MY), design of that member will be
terminated.
And now we come to how these design limitations have a bearing
on the analysis issues. If the user intends to design these members,
as a result of the above restrictions, he/she must model it in such a
way that none of the 4 unacceptable degrees of freedom end up
with a non-zero value anywhere along the length of the member.
That means, if the member ends are defined as supports, the
support conditions must be defined with the above in mind.
Similarly, if the castellated member is attached to other members,
its end conditions (MEMBER RELEASES) must be modeled
taking the above facts into consideration.
The design limitations also have a bearing on the type of loads that
are applied to the member. Loads which cause any of the above-
mentioned four degrees of freedom to end up with a non-zero
value will cause the member design to be terminated.
However,
if the user wishes to only analyze the structure, and is
not interested in performing a steel design, the above described
restrictions for supports, member end conditions or loading are not
applicable.