2002 MSJC Code Seminar Notes 1

[jheidt2543]

I am trying to find where the 0.746 factor comes from when calculating the Allowable Stress Fa for ASD of unreinforced masonry bearing walls in the following example problems:

Example 2a, page 6
Example 2b, page 11
Example 2c, page 15

I did look in the ACI530/ASCE5-02/TMS 402-02 Building Code Requirements for Masonry Structure, page C-25 Eq. (2-12) but didn't find anything.

Thanks in advance for pointing me in the right direction.

 

[jheidt2543]

Additional question:

In example problem 2c, page 16, regarding the Stability Equation, the notes state "Moments and axial forces from lateral loads are not included in this (stability) check."

Why? In a wall just on the verge of instablity couldn't lateral loads be enough to "push it over the edge"?

 

[JAE]

They are just showing you the math....

The first part of the term - 0.25f'm
The second part of the term - (1-(h/140r)^2) = 0.746

They separate the two to give you a feel for the effect of the slenderness on the total allowable stress.

 

[jheidt2543]

JAE,

Now that you turned on the light switch, it seems trivial. It seems that I looked at that for hours, I must have been in a trance.

Thanks

 

[JAE]

Well..honestly, I poured over it for some time looking for the damned 0.746 source as well.