Basic Diaphragm Action



- a large, thin structural element that is loaded in its plane

- sheathing, framing, boundary members

- horizontal beam that distributes force to the vertical
resisting elements in the lateral-force-resisting system



Flexible vs Rigid 

section 3.3

section 9.11



Transverse vs Longitudinal Loading

chords - boundary members ⊥ to the applied force

collectors (struts) - boundary members // to the applied force



Shear vs Bending

sheathing - shear - web

chords - moment (couple) - flanges

 collectors (struts or drag struts) - reactions to shearwalls

drags or collects the diaphragm shear into the shearwall



Lots of Seismic Comments...  pages 9.6-7