Comparison Between Interior and Exterior R/C Beam-Column Joint Behavior


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Title: Comparison Between Interior and Exterior R/C Beam-Column Joint Behavior

Author(s): S. Fujii and S. Morita

Publication: Special Publication

Volume: 123


Appears on pages(s): 145-166

Keywords: anchorage (structural); axial loads; beams (supports); columns (supports); earthquake-resistant structures; frames; hoops; joints (junctions); reinforced concrete; shear properties; tests; Structural Research

Date: 1/1/1991

Eight 1/3 scale specimens, consisting of four pairs of interior and exterior beam-column subassemblages in one-way frames, were tested. To investigate the basic joint shear strength, the test program was so determined that joint shear failure occurred in most specimens prior to beam yielding by using high-strength steel for beam bars. Test variables were beam bar strength, column axial load, and amount of joint hoop. The test results showed: 1) the increase of column axial load level from f'c / 12 to f'c / 4 did not influence the ultimate shear strength of the interior joints, but this increase in column axial load improved the shear strength of the exterior joints nearly 10 percent; 2) the ultimate shear strength represented in terms of nominal shear stress was f'c / 4 for interior joints; 3) when the shear strength of the exterior joints was evaluated on the basis of projected length of hooked beam bars instead of total column depth, nearly the same strength was obtained for both types of joint; 4) the increase of joint shear reinforcement ratio from 0.41 to 1.1 percent did not noticeably effect the behavior for both types of joint; 5) once joint shear strain reached to 0.5 percent degradation of shear rigidity was accelerated under subsequent load reversals.