Frame & Wall Design Procedures

[cancmm]

After a number of years working on bridge-type structures, I'm looking at a low-rise building for one of our newer projects. As such, I have a few questions regarding moment frame and shear wall design:

1) When working with a moment frame, is there a "better" method of determining lateral stiffness than modeling the frame with a unit force and correlating that to deflection? Is there standard equations to use (like with shear walls) that calculate the deflections quickly and easily?

2) I read in an outdated text that concrete moment frames must be poured monolithically. Obviously this is ideal but I can already hear the contractors complaining. Unless the rebar was insufficiently developed or the friction of the joint was too weak in shear, I don't see any reason for this. Any comments?

3) For moment frames with shallow footings, is it common to connect the footings with a strap rather than isolating each footing?

4) If a shear wall (or frame) is angled 45 degrees from the principal lateral load direction, how does it contribute to the stiffness of the system? (cos45? Neglected?)

Thanks!

 

[msquared48]

#3: I commonly do that to prevent the footings from spreading for one. Also, to lower the soil pressures due to overturning - pick up the dead resisting load of both columns.

#4: I commonly use the 45 degree component length of the wall in the line of the applied force, but there are other methods.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask