Experimental Study on Prefabricated Beam-Column Subassemblages

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Title: Experimental Study on Prefabricated Beam-Column Subassemblages

Author(s): Kenzo Yoshioka and Masataka Sekine

Publication: Special Publication

Volume: 123

Issue:

Appears on pages(s): 465-492

Keywords: anchorage (structural); beams (supports); columns (supports); bond (concrete to reinforcement); bond stress; deterioration; failure; grouting; joints (junctions); precast concrete; shear properties; slippage; Structural Research

Date: 1/1/1991

Abstract:
Describes two types of prefabricated beam-column joints designed to save manpower requirements in construction work. The first type consists of making precast subassemblages with beam-column joints and integrated beams. Through-holes are provided in the vertical direction in the beam-column joint to accommodate column reinforcing bars (Type 1). The second type consists of precast subassemblages with beam-column joints and columns integrated. Through holes are provided in the horizontal direction in the beam-column joint to accommodate beam reinforcing bars (Type 2). Column or beam reinforcing bars are passed through the holes in these precast subassemblages; the parts are integrated by subsequent grouting of the holes with high-strength mortar. The earthquake resistance of these precast subassemblages was investigated with cyclic loading tests. The systems are intended for use in a 13-story reinforced concrete building, designed so that its collapse mechanism would be of the beam-yielding type. With Type 1 precast subassemblages, column reinforcing bars grouted and fixed inside sleeve-pipe holes are not subject to stresses extending into the plastic range. Therefore, by suitably designing the anchorage lengths of beam reinforcing bars inside the joints, there will be no slippage of the beam bars. A ductility of more than six times the yielding displacement may be attained. With Type 2 subassemblages, the beam reinforcing bars grouted and fixed inside sleeve-pipe holes are subjected to repeated stresses extending into the plastic range, such that bond deterioration occurs inside the joints. Strength declines at large deformations exceeding three times the yield displacement, and satisfactory ductility is not obtained. Taking test results into consideration, precast subassemblages of the first type are recommended for adoption in the 13-story building.