ASI - Design Guide 12: Bolted End Plate to Column Moment Connections - Web Crippling

[Drapes]

Design Guide 12 of the ASI's Connection Series adopts separate checks for yielding, buckling and crippling of the column web when subjected to a localised compression force.

If it is found that transverse stiffeners are only required to avoid web crippling, there is no corresponding check in the Design Guide which can be used to cater for this. The only check for a column web with transverse stiffeners at the compression flange seems to pertain to the yielding and buckling cases.

Can anybody shed some light on this? Does it simply mean that web crippling can be avoided by adopting a set of transverse stiffeners without the need to actually conduct a check? It seems a little odd to me.

In fact, in addition to all this, AS4100 doesn't even consider web crippling.

 

[ishvaaag]

This is from AISC 360 10 2nd printing, at chapter J where you can find the specs for the numerics (formula J10-4) as well.

8. Additional Stiffener Requirements for Concentrated Forces
Stiffeners required to resist tensile concentrated forces shall be designed in accordance
with the requirements of Section J4.1 and welded to the loaded flange and the
web. The welds to the flange shall be sized for the difference between the required
strength and available strength. The stiffener to web welds shall be sized to transfer
to the web the algebraic difference in tensile force at the ends of the stiffener.
Stiffeners required to resist compressive concentrated forces shall be designed in
accordance with the requirements in Section J4.4 and shall either bear on or be
welded to the loaded flange and welded to the web. The welds to the flange shall be
sized for the difference between the required strength and the applicable limit state
strength. The weld to the web shall be sized to transfer to the web the algebraic difference
in compression force at the ends of the stiffener. For fitted bearing stiffeners,
see Section J7.
Transverse full depth bearing stiffeners for compressive forces applied to a beam or
plate girder flange(s) shall be designed as axially compressed members (columns) in
accordance with the requirements of Section E6.2 and Section J4.4. The member
properties shall be determined using an effective length of 0.75h and a cross section
composed of two stiffeners, and a strip of the web having a width of 25tw at interior
stiffeners and 12tw at the ends of members. The weld connecting full depth bearing
stiffeners to the web shall be sized to transmit the difference in compressive force at
each of the stiffeners to the web.
Transverse and diagonal stiffeners shall comply with the following additional
requirements:
(1) The width of each stiffener plus one-half the thickness of the column web shall
not be less than one-third of the flange or moment connection plate width delivering
the concentrated force.
(2) The thickness of a stiffener shall not be less than one-half the thickness of the
flange or moment connection plate delivering the concentrated load, nor less
than the width divided by 16.
(3) Transverse stiffeners shall extend a minimum of one-half the depth of the member
except as required in Section J10.5 and Section J10.7.



When LRFD 1992 was extant, I did worksheets about the need in yield, web buckling and web crippling. I attach a jpg of the last one.