CIVL3310 STRUCTURAL ANALYSIS
Chapter 11: Displacement Method of Analysis: Slope-Deflection Equations. CIVL3310 STRUCTURAL ANALYSIS. Professor CC Chang. Force vs Displacement Methods. Force methods Choose redundant forces Use compatibility conditions or least work principle to solve these redundant forces
CIVL3310 STRUCTURAL ANALYSIS
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Chapter 11: Displacement Method of Analysis: Slope-Deflection Equations CIVL3310 STRUCTURAL ANALYSIS Professor CC Chang
Force vs Displacement Methods • Force methods • Choose redundant forces • Use compatibility conditions or least work principle to solve these redundant forces • Displacement methods • Choose degrees of freedom (DOFs: displacement or rotation angles) • Relate internal forces to DOFs • Use equilibrium to solve DOFs • Obtain internal forces from DOFs By qB
Degrees of Freedom (DOFs) • Nodes, members (elements/components) and DOFs Nodes Member DOF qB qB C DC qC
Beam under Loading A B L A’ B’ MBA Assume moment/rotation + MAB • Choose degrees of freedom • Relate internal forces to DOFs • Use equilibrium to solve DOFs • Obtain internal forces from DOFs How do MAB & MBA relate to deformation at A & B? A B B’ A’
Slope-Deflection Relationship MAB1+MAB2 MBA1+MBA2 A A B B MBA B’ B’ MBA1 MBA2 A’ A’ MAB MAB1 MAB2 A B B’ A’ Moments to produce such a deformation Moments to resist loads without extra deformation From Table (Fixed end moments, FEM)
Slope-Deflection Relationship D L • Choose degrees of freedom • Relate internal forces to DOFs • Use equilibrium to solve DOFs • Obtain internal forces from DOFs A B MBA1 B’ A’ MAB1
Slope-Deflection Relationship A B MBA1 M1 D B’ L MAB1 A’ M2 B’ M2 M2 M1 M1 A’ + =
Slope-Deflection Relationship MAB1+MAB2 MBA1+MBA2 A A B B MBA B’ B’ MBA1 MBA2 A’ A’ MAB MAB1 MAB2 A B B’ A’ Moments to produce such a deformation Moments to resist loads without extra deformation From Table (Fixed end moments, FEM)
Slope-Deflection Relationship D A B L L A’ B’ • Choose degrees of freedom • Relate internal forces to DOFs • Use equilibrium to solve DOFs • Obtain internal forces from DOFs A B MBA B’ A’ MAB moment/rotation + =