Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Deep Embedded HSA tension capacities in CMU

[Subject Prev][Subject Next][Thread Prev][Thread Next]
The 1997 UBC masonry chapter 21 and ACI 530 Masonry 
Specification give equations to calculate the allowable 
tension load capacities in a masonry wall.  One equation 
is to determine the masonry wall resistance capacity 
(Bt=0.5*Ap*(fm)^0.5) and the other equation is to 
determine the anchor bolt resistance capacity 
(Bt=0.2*Ab*fy).  The Ap in the first equation is the 
projected area calculated using the lesser of (1) the 
anchor embedment depth as the radius in the pi*r^2 
equation and (2) the anchor edge distance as the radius 
in the same equation.  Therefore, if one had a anchor 
bolt in the top of a 8" nominal width masonry wall, one 
would have a 3.81" edge distance and be limited to 
Ap=3.81^2*pi.  Therefore, the code and specification do 
not seem to take into account additional resistance 
capacity provided when deeper embedments are provided.  
In the anchor in the top and middle of the masonry wall, 
it appears that one could reasonably determine Ap based 
on the area of the projected cone on the masonry surface 
for deeper embedments.  In this case, it would closely 
resemble a rectangle and the Ap equation would be Ap =
(Embedment Depth * 2) + (Edge Distance * 2).

In addition, the code and specification Bt equation to 
determine the steel resistance capacity is less than 
shown by the AISC Manual of Steel Construction.  The 
reasoning for this is stated in the ACI 530 
Specification Commentary section as 
follows "Bent bar anchors often failed by completely 
sliding out of the specimen."  Therefore, the reduced 
steel anchor bolt tension resistance capability.  
However, if one uses headed stud anchors, should not an 
increased steel bolt tension resistance capability be 

Have these questions been addressed in any committees, 
codes, or standards?

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at:
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*   Questions to seaint-ad(--nospam--at) Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: 
******* ****** ****** ****** ******* ****** ****** ********