Summary of Chapter 3 Tube Action (Square tube,3/4M,0.9V) Frame Action (Total frame action,ib>4ic,P.I.=0.5h Cantilever Action (Pin connection,Apin=4Afix) Shear Lag Effect (Framed tube,o max=1.50)Summary of Chapter 3 Tube Action (Square tube, 3/4M, 0.9V) Frame Action (Total frame action, ib>4ic, P.I. =0.5h ) Cantilever Action (Pin connection, Δpin=4 Δfix) Shear Lag Effect (Framed tube, σ max=1.5 σ )