Postyield

VAL5 — Steel beam cyclic validation (WUF-W connection, SAC specimen LT6, W36x150)

A full-scale steel wide-flange beam in a welded unreinforced-flange, welded-web (WUF-W) moment connection, taken through the AISC 341 / FEMA-350 qualification protocol out to 4% total drift.

Time
About 5 minutes
Level
All levels
You'll need
None — this is a reference document
You're done when
You can see how VAL5 compares to its reference
On this page
  1. Description
  2. Reference
  3. Model
  4. Response comparison
  5. Comparison
  6. Conclusion

← Validation

VAL5 — Steel beam cyclic validation (WUF-W connection, SAC specimen LT6, W36x150)

Description

A full-scale steel wide-flange beam in a welded unreinforced-flange, welded-web (WUF-W) moment connection, taken through the AISC 341 / FEMA-350 qualification protocol out to 4% total drift.

Reference

Ricles, Mao, Lu & Fisher (2002), J. Struct. Eng. 128(4), specimen LT6; SAC Steel Project connection database.

Model

A cantilever beam of the tested wide-flange section, with a distributed fiber-section hinge over the steel section at the base (the connection), sized to the specimen's own measured yield strength. The beam is pushed to increasing rotation levels matching the AISC 341 / FEMA-350 qualification protocol, out to 4% total drift.

The beam cantilever model with a fiber hinge at the connection.
The beam cantilever model with a fiber hinge at the connection.
Depth, d35.9 in
Flange width, bf12 in
Web thickness, tw0.625 in
Flange thickness, tf0.94 in
Strong-axis inertia, Ix9,040 in⁴
Section modulus, Sx503.6 in³
Plastic modulus, Zx581 in³
Measured yield strength, Fy56 ksi
Elastic modulus, E29,000 ksi
Shear span, Lcl177 in
Plastic hinge length, Lp17.95 in

Response comparison

vfopro simulation Hand-calc reference

Simulated response; no digitized point-by-point test trace was available for this specimen (see Conclusion), so hand-calculated reference points are marked instead.

Comparison

QuantityReferencevfopro% diff
Max rotation reached, theta = disp/Lcl (rad) — protocol completion check0.040.040.00%
Base moment near theta=thetaY=0.0037 rad (kip-in) vs My=Fy*Sx (hand-calc, first-yield check)28,201.627,622.8-2.05%
Base moment near theta=0.02 rad (kip-in) vs Mp=Fy*Zx (hand-calc)32,53631,440-3.37%
Base moment near theta=0.04 rad (kip-in) vs 1.10*Mp (hardening allowance)35,789.635,053.8-2.06%

Conclusion

The moment reached at first yield, at 2% drift (plastic moment) and at 4% drift (with expected cyclic hardening) all matched hand-calculated values within about 3.5%, and the model reached the full 4% drift the real connection also completed without fracture. This checks strength at key rotation levels rather than the full hysteresis loop; a reliably digitized point-by-point trace for this specimen was not available for this edition of the document.

Last updated September 22, 2026 · applies to vfopro 20260922.0.0 or later