Rotational Stiffness of Deeply Embedded Column–Base Connections

Rodas, Pablo Torres; Zareian, Farzin; Kanvinde, Amit

doi:10.1061/(asce)st.1943-541x.0001789

Cited by 25 publications

(15 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In particular, All columns considered herein were assumed to be ideally fixed at the ground level. The inherent flexibility of exposed or embedded column base connections may significantly influence the column residual axial‐shortening Field observations from past earthquakes (eg,) along with numerical studies suggest that the inelastic behavior of columns in structures as well as bridge piers could be considerably affected by soil‐structure‐interaction, which was neglected in the present study. The paper findings suggest that recently proposed structural solutions may be further exploited to potentially minimize steel MRF column structural damage due to local buckling.…”

Section: Limitations Of the Present Study And Future Workmentioning

confidence: 79%

Proposed methodology for building‐specific earthquake loss assessment including column residual axial shortening

Elkady

Güell

Lignos

2019

Earthq Engng Struct Dyn

View full text Add to dashboard Cite

Summary This paper proposes methodological developments for quantifying the impact of residual axial shortening of first‐story steel columns on earthquake loss estimations in steel moment‐resisting frame (MRF) buildings. A new formulation is proposed that accounts for the likelihood of having to demolish a steel MRF building due to column residual axial deformations in addition to residual story‐drift ratios. The formulation is informed by means of data from a comprehensive survey conducted worldwide to assess the likelihood of steel column repairability due to residual axial shortening. A practical method for quantifying column axial‐shortening in parameterized system‐level numerical simulations is presented. The proposed approach is illustrated by conducting economic seismic loss estimations in two case‐study steel MRF buildings designed in urban California according to the current seismic design practice. It is found that when the ground‐motion duration is appreciable, the examined steel MRFs are more prone to column axial‐shortening than residual story‐drifts at moderate to high seismic intensities. The results suggest that economic losses due to demolition may be underestimated if column residual axial‐shortening is neglected from loss estimations. Limitations as well as directions for future research are discussed.

show abstract

Section: Limitations Of the Present Study And Future Workmentioning

confidence: 79%

Proposed methodology for building‐specific earthquake loss assessment including column residual axial shortening

Elkady

Güell

Lignos

2019

Earthq Engng Struct Dyn

View full text Add to dashboard Cite

show abstract

“…From the standpoint of steel MRF design and collapse behavior, the above findings are relevant for two reasons: (1) moment frames are usually designed (and simulated) assuming an ideally fixed base boundary condition, entirely disregarding the effect of base flexibility on the MRF seismic response, and (2) recent research (Barnwell 2015;Rodas et al 2017) has shown that even if designed as fixed, column bases of various types have considerable rotational flexibility. Zareian and Kanvinde (2013) have examined the "first-order" implications of such simplifications.…”

Section: Introductionmentioning

confidence: 99%

Seismic Stability of Wide-Flange Steel Columns Interacting with Embedded Column Base Connections

2019

View full text Add to dashboard Cite

The rotational flexibility of column base connections is commonly assumed to be detrimental to the seismic response of steel Moment Resisting Frames (MRFs) because it increases story drift demands and promotes soft-story formation by lowering the point of inflection, thereby exacerbating the moment demand at the first-story column top end. However, recent experimental research indicates that wide-flange steel columns with flexible boundary conditions may show enhanced response because base connection flexibility delays the plastic hinge formation and local buckling progression within the column cross-section near the base. Local buckling greatly reduces the lateral and torsional restraint at the column ends such that the delay in local buckling also delays member instabilities, which often control the deformation capacity of wide-flange steel columns. This effect is examined parametrically through 2160 Continuum Finite Element (CFE) simulations validated against physical experiments. Parameters interrogated include the applied axial load ratio, the column length, and the lateral loading protocol for the column sections, along with five levels of column base connection flexibility. The results indicate that base connection flexibility has a significant (and positive) influence on key aspects of column response, including: (1) lateral deformation capacity, which is on average 40~50% greater for a realistic value of flexibility, relative to a fixed-base condition, and (2) residual column axial shortening, which is important from the standpoint of retrofit and reparability (a 30-60% decrease). These benefits are more pronounced in cyclic (versus monotonic) loading histories and for members with cross-sections more prone to out-of-plane instability.

show abstract

“…These studies have been synthesized into design documents for base connections, including the American Institute of Steel Construction's (AISC) Design Guide One (Fisher and Kloiber 2006) and the AISC Seismic Design Manual (2006), as well as the Structural Engineers Association of California Structural/Seismic Design Manual Volume 1 (SEAOC 2015). More recent studies have addressed rotational flexibility of these connections (Kanvinde et al 2012, Torres-Rodas et al 2017 and the effect of this flexibility on frame response (Zareian and Kanvinde 2013). Other work has focused on developing strategies for finite element simulation of column base connections (Kanvinde et al 2013, Stamatopoulos andErmopoulos 2011).…”

Section: Introductionmentioning

confidence: 99%

Seismic Demands in Column Base Connections of Steel Moment Frames

2018

Self Cite

View full text Add to dashboard Cite

Methods for the seismic design of base connections in steel moment frames are well-developed and routinely utilized by practicing engineers. However, design loads for these connections are not verified by rigorous analysis. This knowledge gap is addressed through nonlinear time history simulations using design-level seismic excitation that interrogate demands in column base connections in 2-, 4-, 8-, and 12-story steel moment frames, featuring base connections that reflect current U.S. practice. The results indicate that: (1) for exposed base plate connections, lower bound (rather than peak) estimates of axial compression are suitable for design because higher axial forces increase connection strength by delaying base plate uplift; (2) even when designed as pinned (as in low-rise frames), base connections carry significant moment, which can be estimated only through accurate representation of base flexibility; and (3) the failure of embedded base connections is controlled by moment, which may be estimated either through overstrength or capacity-based calculations.

show abstract

Rotational Stiffness of Deeply Embedded Column–Base Connections

Cited by 25 publications

References 8 publications

Proposed methodology for building‐specific earthquake loss assessment including column residual axial shortening

Proposed methodology for building‐specific earthquake loss assessment including column residual axial shortening

Seismic Stability of Wide-Flange Steel Columns Interacting with Embedded Column Base Connections

Seismic Demands in Column Base Connections of Steel Moment Frames

Contact Info

Product

Resources

About