Cyclic Behavior of Gabled Frames with Web-Tapered Columns and Rafters

Area of Science:

• Structural Engineering
• Seismic Performance Evaluation
• Steel Structures

Background:

• Steel gabled frames (SGFs) are crucial in seismic-prone regions.
• Understanding the seismic performance of SGF joints is vital for structural safety.
• Previous research indicates joint behavior significantly influences frame response.

Purpose of the Study:

• To investigate the seismic performance of 1/2-scale steel gabled frames with reduced joint stiffness.
• To evaluate the impact of joint parameter variations (end-plate thickness, bolt diameter, bolt quantity) on SGF behavior.
• To compare experimental results with finite element model predictions.

Main Methods:

• Cyclic loading tests were performed on three half-bay SGF specimens (SV1, SV2, SV3) with modified joint stiffness.
• Specimen SV1 featured reduced end-plate thickness and bolt diameter; SV2 had fewer bolts; SV3 had a reduced bolt diameter.
• A refined finite element model was developed and validated against experimental data.

Main Results:

• Specimen SV1 failed by local buckling of the rafter's lower flange; SV2 and SV3 failed by local buckling of the rafter's upper flange.
• All joints remained intact, suggesting a substantial safety margin in the prototype joint.
• Hysteresis curves were incomplete, indicating limited ductility and energy dissipation capacity.

Conclusions:

• Joint stiffness modifications had a minor effect on the overall hysteresis performance of the SGFs.
• The prototype joint design exhibits a significant safety margin.
• The study highlights limited post-buckling strength utilization and distribution in the tested frames.