Cyclic response sensitivity of post-tensioned steel connections using sequential fractional factorial design

Abstract

Through the use of post-tensioned (PT) elements in steel beam-column connections, steel buildings under seismic excitations can return to their plumb position, displaying negligible permanent deformation. The cyclic behavior of a PT connection is affected by several design parameters. This paper aims at identifying the significant factors which affect the cyclic response of steel PT connections with top-and-seat angles. A sequential fractional factorial design-of-experiment methodology is used to statistically evaluate the effects of different design factors as well as their interactions on the cyclic response of PT connections. To this end, 3D finite element models are first developed to accurately simulate the cyclic behavior of the connections. After validating the finite element results with the past experimental data, a two-stage (sequential) sensitivity analysis is conducted. Eight potential factors, including the material and geometric properties of steel angles, reinforcing plates, and bolts, are considered. The cyclic response of connections is examined in terms of stiffness, strength, energy dissipation capacity, and residual displacement. From this parametric study, the significance of the design factors is determined with respect to each response. Additionally, regression models are presented to estimate the response quantities for other PT connection configurations with the same beam and column sections.