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RE: Seismic Load Factors

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2.  Are there any other mystery factors buried in the code for masonry?

Watch out for

If we get a question for flexible diaphragm supported by masonry walls:
1633.2.9 item 3,  R = 4.  Scale up forces to design a flexible diaphragm
supported by masonry or concrete walls.
1633.2.9 item 4,  Aspect ratio of 2.5.  Will probably govern for large bay
systems. (warehouses, etc)

1633.2.8.1:  ap =1.5 and Rp = 3.0.  Minimum wall anchorage load is 420plf.
(300plf at ASD)
1633.2.8.1 item 4:  checking wall anchorage (portion governed by steel;
anchor bolts, hold-downs) increase force by 1.4.  (this is not the "USD" to
"ASD" conversion factor).  If you use USD, then Fp= 1.4*Fp(USD).  If using
ASD Force = 1.4*Fp(USD)/1.4.
1633.2.8.1 item :  checking wall anchorage (portion governed by wood,
nailing at ties) decrease force by 0.85.

If we get a shear wall question (design using ASD)
2107.1.7:  (ASD) increase force in wall by 50%.

If we get a splice question:
2107.2.12 lap splice increase of 50% could be triggered.

If we get a boundary element question,
good luck.

David Guerrero
GBDH Design Group
Sacramento, CA

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