Experimental apparatus for the deflection analysis of statically determinate and indeterminate plane frames
A rigid-cornered steel portal of either U-shape or S-shape is clamped at one end; the opposite end can be left free (statically determinate cantilever frame) or seated on a roller (statically indeterminate single-redundant frame). Point loads at arbitrary positions deform the frame; two dial gauges record the horizontal sway and vertical deflection. The apparatus gives the student a platform on which to apply first-order elastic theory, the principle of superposition and — above all — the principle of virtual work to compute both deformations and the redundant support reaction, then compare directly to the measured values.
Experiments
Elastic deformation of U-shaped and S-shaped frames under point loads
Statically determinate and statically indeterminate configurations
First-order elasticity theory — bending-moment diagram and elastic line
Application of the principle of superposition
Application of the principle of virtual work:
virtual-force method — for deformations
virtual-displacement method — for support reactions
Verification of the Maxwell–Betti reciprocal theorem
Horizontal thrust and side-sway in a portal frame
Comparison of calculated and measured deformations
Frames
Materialsteel, rectangular solid cross-section
Cross-section20 × 10 mm
U-shaped portaledge length 600 × 600 mm
S-shaped frameedge length 600 × 600 mm
Supports
Clamping pillars1 long + 1 short — for both determinate and indeterminate setups
Roller bearing1 — introduces the redundant constraint
A complete set of experimental modules covering the core topics in strength of materials — elastic line, torsion, Euler buckling, frame deformation, plastic bending, and static equilibrium.
