Presentation Transcript
Theory of plane and space trusses :Theory of plane and space trusses Dr. Abdul Razaq Touqan
Department of Civil Engineering
Local versus global coordinates :Local versus global coordinates Element axes are not all the same.
So there is a need for a coordinate transformation
Coordinate transformations from local to global :Coordinate transformations from local to global
Coordinate transformations from local to global :Coordinate transformations from local to global
Coordinate transformations from local to global :Coordinate transformations from local to global Transformation matrix from global to local T is:
Notice for an orthogonal matrix, the inverse transformation from local to global is quite easy because:
Coordinate transformations from local to global :Coordinate transformations from local to global -The element stiffness matrix in local coordinates is:
-since truss member connects two nodes, the transformation:
Coordinate transformations from local to global :Coordinate transformations from local to global -element equation in local coordinate:
-transform to global
-multiply both sides by T-1
Global stiffness matrix :Global stiffness matrix
Plane truss example :Plane truss example Analyze the truss shown, given:
Slide 10:Plane truss example (continues)
Member connects nodes 1?j
Plane truss example (continues) :Plane truss example (continues)
Plane truss example (continues) :Plane truss example (continues)
Stress equation for PT :Stress equation for PT
Space truss :Space truss 3D trusses
Space truss :Space truss
Space truss global stiffness :Space truss global stiffness
Example :Example Analyze the truss shown, given
ST example (solution) Member connects nodes 1?j :ST example (solution) Member connects nodes 1?j member(1):1 to 2
ST example (solution) :ST example (solution) member(2): 1 to 3
ST example (solution) :ST example (solution) -member (3): 1 to 4
ST example (solution) :ST example (solution) -combining equations
ST example (solution) :-equation of stress becomes ST example (solution)
ST example (solution) :ST example (solution)
Slide 24:End of PT and ST analysis Let Learning Continue