Date of Graduation

5-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Prinz, Gary S.

Committee Member

Hale, W. Micah

Second Committee Member

Murray, Cameron D.

Third Committee Member

Dominguez, Damaso

Keywords

Earthquake; Fatigue; Finite element analysis; Sesimic Design; Steel structures

Abstract

Special moment frames (SMFs) are frequently used in high seismic areas for architecturally constrained designs. SMFs provide lateral system stiffness without the use of braces that often obstruct views and architectural features. Current American Institute of Steel Construction (ASIC) provisions (AISC 341-16) provide prequalified SMF connection details; however, all prequalified details only consider orthogonal connections between the beam and column. This dissertation investigates the effect of adding skew within SMF beam-to-column connections. The study presented herein involves system-level dynamic time-history analyses of skewed SMF connections, the analytical component-level investigation into the effect of the concrete slab on behavior of the SMF connections, and experimental testing of skewed SMF connections.

Results from system-level dynamic investigations show that skewed buildings experience increased column twist related to columns in orthogonal configurations, but decreased column axial demands likely due to reduced connection stiffness.

Experimental testing of the skewed SMF configurations demonstrates adequate cyclic performance at 10, 20, and 30 degrees of skew (with both shallow and medium-depth columns), meeting the minimum acceptance criteria of AISSC 341-16. However, it was noticed that an increase in skew reduces the connection moment capacity, and increases column twist and column flange yielding. Large column twist observed during the medium-depth column test at having 30 degrees of skew may present column stability concerns under large axial loads. Die penetrant investigations following cyclic testing indicate no fractures within the welded zones of each specimen.

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