SSW with no boundary elements - flexural and shear design

[EngineerRam]

Hello,

When designing special shear walls with no boundary elements (i.e. reinforcement at ends is not confined), do you consider the contribution of the end reinforcement in compression to the flexural capacity of the wall? The reason I am asking is because making or not making this assumption can be unconservative depending on the case:

1) If I disregard the end reinforcement in compression, my flexural capacity of the wall is reduced. If I design the wall similar to an SMF column (i.e. utilizing the fi factor of 0.75 for the ductile limit state and 1.25fy), the design shear associated with the flexural capacity is reduced.

2) If I include the end reinforcement in the flexural capacity, my flexural capacity is increased, although I am not confined by ties to be able to use this reinforcement in compression from my interpretation of the code.

Thanks

 

[HTURKAK]

My points are ;

- If the boundary element is designed for special boundary elements ,

- If you provide ties as per ACI 318-14 Clause 18.10.6.5,

You can include end reinforcement in compression..








Don't underestimate a nail. A nail saves a horseshoe, a horseshoe saves a horse, a horse saves a commander, a commander saves an army, an army saves a whole country.. GENGHIS KHAN

 

[EngineerRam]

Yes, but by disregarding the end reinforcement in compression, are you not underestimating the moment capacity of the wall and the associated developed shear in the ductile limit state? Even if not confined, the bar would still provide some compressive capacity to the flexural strength.

 

[HTURKAK]

If not confined, the end reinf. is prone to buckling..

Pls look R18.10.6.5

.. Cyclic load reversals may lead to buckling
of boundary longitudinal reinforcement even in cases
where the demands on the boundary of the wall do not
require special boundary elements. For walls with moderate
amounts of boundary longitudinal reinforcement, ties are
required to inhibit buckling....






Don't underestimate a nail. A nail saves a horseshoe, a horseshoe saves a horse, a horse saves a commander, a commander saves an army, an army saves a whole country.. GENGHIS KHAN