Alternative Support Systems for Cantilever - National Transportation ...

4.7 Summary of Torsion and Flexure Design
For the torsion and flexure test, once again the key element of the design that dictated the
rest of the design was the concrete shaft. The concrete breakout or bearing strength of the shaft
with the embedded pipe and plate apparatus in torsion and flexure was the ultimate strength of
the entire system. All other components of the system were designed to preclude failure from
these elements. Appendix A shows detailed and dimensioned drawings of the testing apparatus.
Appendix B shows detailed calculations for the test apparatus.
Table 4-2, shown below, summarizes the essential design components, their equivalent
torsional and flexural strengths, whether the strengths are mean or nominal, and their ratio
compared to the interaction torsional and flexural strength values.
Table 4-2. Summary of pertinent design strengths for torsion and flexure test with 5500 psi
concrete
Mean or Predicted Ratio of Failure
Failure Mode
Embedded Pipe and Stiffeners
Equivalent Torsion from Shear
Capacity Nominal? Load Capacities
Parallel to an Edge
Equivalent Torsion from Side Face
348 kip-ft Mean 38.67 2.42
Blowout
Equivalent Flexure from Shear Parallel
523 kip-ft Mean 58.11 3.63
to an Edge
Equivalent Flexure from Side Face
218 kip-ft Mean 27.25 1.70
Blowout
Anticipated Interaction
337 kip-ft Mean 42.13 2.63
Torsional Strength 144 kip-ft 16.00 1.00
Flexural Strength
Circular Shaft - 30"
128 kip-ft 16.00 1.00
Torsion 253 kip-ft Nominal 28.11 1.76
Flexure
"Superstructure" Pipes - 16" x .5"
296 kip-ft Nominal 37.00 2.31
Torsion 359 kip-ft Nominal 39.89 2.49
Flexure 392 kip-ft Nominal 49.00 3.06
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