Anchor‐yield exposed column bases for minimizing residual deformations in seismic‐resistant steel moment frames

Abstract

This paper explores the concept of dissipative exposed column base connections by means of anchor rod yielding. This concept aims at enhancing the seismic performance of low-rise steel moment-resisting frames (MRFs). A mechanics-based model is proposed that explicitly simulates a broad range of damage mechanisms observed in exposed column bases. The model is implemented in a frame finite element analysis program and its hysteretic performance is validated with experimental data available in literature. Incorporating this modeling feature in standard nonlinear response history analyses offers new insights in steel MRF responses. It is shown that when low-rise steel MRFs adopt a dissipative anchor-yield column base concept, they are less likely to experience residual story drift ratios during low-probability of occurrence seismic events. It is also found that low-rise steel MRFs designed with non-dissipative exposed column base connections are more prone to demolition than dissipative ones, due to their higher column residual axial shortening, particularly when ground motion duration is an important feature of the seismic hazard. Limitations of the present work are also discussed.

Probabilistic seismic performance assessment of steel moment‐resisting frames considering exposed column‐base plate connections with ductile anchor rods

“…Instead of using point‐hinge hysteretic models 37 for ECBP connections in frames, 7,9 this study selected the LEB model recently developed by Hassan et al 13 . In fact, this model can explicitly simulate the axial force–moment interaction and axial force variation during seismic loading, which are usually important for ECBP connections in SMRFs due to dynamic overturning effects 8 . Also, the selected model can facilitate the investigation of BCF through the simulated base connection components; details of this aspect are discussed subsequently in Section 3.1.…”

“…Designing ECBP connections through this approach is costly, usually resulting in thick plates and multiple large anchor rods. 2 Moreover, recent experimental [3][4][5][6] and numerical [7][8][9] studies on the seismic performance of ECBP connections reveal their high rotation capacities (> 5%). These capacities are achieved even without any explicit detailing for ductility.…”

Cyclic behavior and design methodology of exposed base plates with extended anchor bolts

“…EBP-EABs can be modeled with a rotational spring using an appropriate phenomenological model similar to models developed by Torres-Rodas et al [17] for exposed base plates. Furthermore, studies conducted in the past ( [2,3,19]) indicate that the seismic demands on CBCs can be safely reduced if their hysteretic characteristics are accounted for when assessing the overall SMF behavior. Naturally, though, CBCs designed for lesser forces are more flexible.…”

“…Zareian and Kanvinde [1] studied the impact of the base rotation flexibility on the response of SMFs. Modern studies have addressed issues related to the hysteretic characteristics of CBCs [17][18], and computational studies based on sophisticated Finite Element (FE) models (e.g., [9,19]) have explored internal forces and stress distributions within the components of CBCs.…”

Nonlinear Finite Element Models for Embedded Base Connections

“…Column Base Connections are one of the most important components of Steel Moment Frames (SMFs). Several researchers [1][2][3][4][5][6] have demonstrated their significant influence on the seismic performance of SMFs systems. Because of this, these connections have been extensively studied over the last decade in different programs [7][8][9][10][11].…”