Available at: https://digitalcommons.calpoly.edu/theses/3293
Date of Award
6-2026
Degree Name
MS in Civil and Environmental Engineering
Department/Program
Civil and Environmental Engineering
College
College of Engineering
Advisor
Mohammadreza Eslami
Advisor Department
Civil and Environmental Engineering
Advisor College
College of Engineering
Abstract
Slotted web connections produce consistent and meaningful improvements in the cyclic behavior of bare and composite beam-to-HSS column connections. Across the eight connections investigated in this thesis, the introduction of a slotted web increased rotational capacity by approximately 7% to 37% and increased cumulative energy dissipation at the strength-degradation limit by approximately 37% to 81%. These improvements were accompanied by only a small reduction in ultimate flexural resistance on the order of 3% to 8%, attributable to the loss of web cross-section at the slot and, for the more flexible H/t = 16 columns, to increased out-of-plane deformation of the HSS column flange. The beneficial effects of the web slot were observed for both bare and composite configurations and for HSS column width-to-thickness ratios of 16 and 0, with the largest improvements occurring at the more flexible column compactness (H/t = 16).
The Slotted Web (SW) beam-to-column connection is a prequalified connection in AISC 358-22 whose proprietary restrictions were recently removed, opening opportunities for independent evaluation of its seismic performance. Existing studies have been limited to bare steel beams connected to wide-flange columns, leaving the behavior of SW connections to Hollow Structural Section (HSS) columns largely unexamined. This thesis numerically investigates the cyclic behavior of eight full-scale beam-to-HSS column connections using finite element simulations in Abaqus, varying the presence of web slots, reinforced concrete slabs, and HSS column width-to-thickness ratios under the AISC 341-22 loading protocol. The numerical models incorporate combined isotropic-kinematic hardening, Concrete Damage Plasticity, and a stress triaxiality-dependent ductile damage criterion to capture low-cycle fatigue and ultimate fracture. The modeling methodology is part of an ongoing research program at Cal Poly San Luis Obispo, UC Berkeley, and collaborating institutions, and has been validated against full-scale experimental specimens covering the principal features investigated in this thesis. The findings support the use of slotted webs as an effective detailing strategy for both new construction and seismic rehabilitation of beam-to-HSS column connections.