Diaphragm Design

[PEinVA]

I am running through a renovation of a strip mall and have a few questions for clarification:

1. When doing diaphragm design for E/W lateral forces, do I apply load combinations? So that I would really be using either W or 0.7E (equation 16-10 IBC '03)? Obviously for my shear wall I would use combinations, but that's because the D or L from those equations also plays into it. However, for the diaphragm only the lateral load comes into play. I would assume I would have to use the combination because we design all our elements to this.

2. With a flexible diaphragm (only metal deck) if I have one long wall on one side, and 2 walls split by 10' on the other side, I just split the load 50:50 each side and then split the 50% up according to stiffness on the side with 2 walls?

3. As long as wind controls I don't need to design anything for the minimum force for the collector elements in 1605.4.

Thanks in advance.

RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[PEinVA]

Ok, just found section 1620.2.5 which basically answers my question about diaphragms.

The equation is provided in 16-60 but it provides a very low value as compared to the value obtained using the equivalent lateral force method Cs*W = V. My V is ~3 times the value of Fp provided in the diaphragm equation.

Nothing in commentary of ASCE 7 or IBC '03

RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[PEinVA]

Ok, well in ASCE it states max load from distributed seismic load OR the question 16-60. So I will just use my larger value.

Now onto the Maximum Seismic Load Effects.

Do these apply if the Basic Seismic Load Effects don't control design? In other words, will I design my diaphragm and shear walls for my wind load, and connection to my wall (only thing that specifically requires OMEGA factor in design) with the Max. Seismic Load Effects?

Anyone?

RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke