expansion plus movement join
 

expansion plus movement joint
if you have a joint between a new and existing building that will be serving as both an thermal expansion and movement joint for drift, should the maximum of these 2 movements be added together?
i think i would take the maximum thermal movement say 1" for each building and add to that the seismic drift say 3" for each building for a total of an 8" joint (since i don't know how hot or cold it will be when an earthquake hits). do you think this is overkill?
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8" is theoretically correct. you can reduce it by say 1/8" hoping that peak earthquake will not strike on the peak days of summer but that is unsubstantiated argument with very little gain.
ciao.
i think the joint width should be based on the addition of 3 factors:
thermal movement, drift, and diaphragm deflection relative to drift.