Description

A reinforced-concrete column under cyclic lateral loading with a sustained axial load, reproducing a specimen from a widely used column test database.

Reference

Lynn et al. (1996), specimen 2CLH18; PEER/UW Structural Performance Database.

Model

A cantilever column, its length equal to the specimen's own reported shear span, with a distributed fiber-section hinge (concrete and longitudinal reinforcing-steel fibers) at the base, using a plastic hinge length derived from Paulay & Priestley (1992). A constant axial load is applied and held first, then a cyclic lateral displacement protocol — extracted from the specimen's own measured response, since no separate commanded-protocol record exists for this physical test — is applied at the free end.

Loading protocol applied

Response comparison

Full loading history, physical test vs. vfopro simulation.

Comparison

Conclusion

The longitudinal reinforcement uses a 5% post-yield hardening ratio. Under the 10% validation criterion, 26 of 36 amplitude/sign bands are within 10%. From 0.4 in through 1.6 in the simulated peak force is within about 3–10% of the test on both sides of the loop: the negative peaks are typically 3–8% low and the positive peaks 8–10% low, so the model is slightly conservative in strength over the whole mid- and large-amplitude range. Two of those bands (0.6–0.7 in and 1.1–1.2 in, positive side) sit just outside the criterion at about 10.5%. The remaining differences are at the extremes of the record. The smallest-displacement bands (up to about 0.4 in) differ by up to about 24% on the positive side, and the first 0.0–0.1 in negative band is about +40% — small-force readings in the pre-yield range where measurement noise and the initial cracked stiffness dominate the percentage. The last two bands (1.6–1.8 in) are at and beyond the specimen’s own reported failure displacement (about 1.7 in), where the real column loses strength to longitudinal-bar buckling. The fiber hinge does not include that degradation mode, so it keeps carrying about 48 kip while the test drops to roughly 11–36 kip; those rows also cross zero force within their displacement bin, which inflates the percentage difference further — a known artifact of comparing by displacement bin. Confinement and hinge-length calibration remain possible refinements; see Scope & Limitations on the overview page.