Comparative Experimental and Numerical Evaluation of Passive Damping in a Slender Steel Frame

Slender steel frames are flexible and lightly damped, so dynamic actions such as earthquakes and wind can govern their response. Design codes such as ASCE 7 and Eurocode 8 permit the equivalent static (lateral force) procedure only for regular, short-period structures and require dynamic analysis otherwise. This study evaluates, experimentally and numerically, how effectively viscous dampers (VDs), a tuned mass damper (TMD) and their combination (TMD + VD) reduce the dynamic response of a laboratory-scale, four-storey, two-dimensional steel frame. The frame was tested on a uniaxial shaking table under a harmonic base excitation with a peak acceleration of 0.398 g in four configurations: bare frame, frame with VDs in the first two storeys, frame with a roof TMD and frame with both. The measured responses were then reproduced in SAP2000 using fast nonlinear analysis. Compared with the bare frame, the measured roof displacement decreased by 55.0%, 88.7% and 90.2%, and the peak inter-storey drift ratio by 48.4%, 89.4% and 88.5%, for the VD, TMD and TMD + VD configurations, respectively. The numerically computed peak base shear decreased by 84.2%, 89.8% and 97.0%. The numerical roof displacements were within 6.2% of the measured values. The TMD provided most of the reduction, while the added VDs further reduced the lower-storey drifts and the base shear.