Cyclic inelastic tests on built-up steel columns including base-plate connections

The paper describes both experimental results and theoretical predictions regarding the cyclic inelastic lateral forcedisplacement response of built-up steel columns with partially-restrained base-plate connections. Two specimens were fabricated and tested, to represent samples of real columns extracted from an existing industrial building. Both columns were made of two I shapes connected by battens, but with significant differences in the scheme of battening from one specimen to the other. The base plate connections also were significantly different from one case to the other, in terms of both design concept and local detailing. Preliminary tests were carried out in the elastic range of response, under varying levels of axial force. Such elastic tests were used to measure variations of the initial stiffness and corresponding yield displacements with the applied axial force. Subsequently, a cyclic loading test was carried out, per each specimen, to investigate the inelastic response. The plastic mechanisms and hysteresis response of the two specimens, as resulting from the experimental tests, are firstly described and commented. Subsequently, detailed finite-element models were developed for both specimens using the Abaqus software. After describing the essential features of the numerical models, the paper illustrates and discusses comparison of theoretical predictions with experimental results.