Collector (Strut) Forces

 

Collectors...

• pull or drag the unit shear in an unsupported segment of a diaphragm (over an opening) into the supporting elements of the shearwall

• are parallel to applied lateral force

• are called drag struts or ties

• are called collectors in IBC, ASCE 7

• are typically top plates

 

Chords and collectors swap as applied force changes direction

1. determine chord forces

2. determine collector forces

   1. multiple FBDs  (textbook example 9.12 method 1)

   2. graph  (textbook example 9.12 method 2)

   3. conservative shortcut:  unit shear x opening length

3. find maximum force

4. design members for that force  (textbook chapter 7)