Retro tting I-beam to double-I built-up columnconnections using through plates and T-stiffeners

Double-I built-up sections have been used extensively in Iran, according to previous versions of Iranian building codes. Despite recent developments in steel moment connections, based on studies for I-beam to H-shaped column connections, there are few documents available for I-beam to double-I built-up column connections. Recent studies have revealed that connections with double-I built-up columns exhibit dierent behavior compared to connections with H-shaped columns. Due to excessive out-of-plane deformations of the cover plate in non-retrotted moment connections, they have semi-rigid behavior. The objective of this study is to build on previous studies and to investigate strain distribution patterns and load transfer mechanisms in the retrotted I-beam to double-I built-up column connections using plates and T-stieners. In this paper, both horizontal and vertical elements of the T-stieners were modied and studied. Analytical models were designed and analyzed under cyclic and monotonic loadings. Three dierent indices were computed in the connection region in order to assess the local failure potential and the moment-rotation hysteretic curves were employed to evaluate the seismic performance of the connections. With the proposed congurations, strain is uniformly distributed within the critical elements. Moreover, excessive deformation of the column cover plate is eliminated