The effect of confining reinforcement on the ductility of reinforced concrete beams
McDonald, J. E. (James E.)
Technical reportAbstract: Some means of improving the compressive strain capacity of concrete is necessary to provide the ductile members or connections which will safely allow for formation of the plastic hinges assumed in designs based on collapse and energy-absorption concepts. The primary objectives of this investigation were to evaluate the effects of various types of confining reinforcement (helices, plane and tubular meshes, and rectangular ties) on the static stress-strain characteristics of rectangular concrete prisms tested in uniaxial compression, and, based on the results of these tests, determine the effectiveness of using selected confining reinforcement in the compressive zone of reinforced concrete flexural members to increase their ultimate strength and ductility. One hundred and eighteen 4- by 4- by 12-in. concrete prisms (one hundred and twelve with and six without confining reinforcement) were cast and tested. The ability of confining reinforcement to increase the ultimate strain capacity and ductility of rectangular concrete prisms in uniaxial compression was clearly demonstrated by the results of these tests. Concrete properly confined by lateral reinforcement had a considerable load-carrying capacity up to strains in excess of two percent, or more than six times the amount of strain usually considered as ultimate for concrete. The data indicate that the horizontal plane mesh (14-gage wire; 1-by l-in. openings) was the most efficient confining reinforcement of those investigated. Within the range of spacings, sizes, and mesh openings studied, it appears that the primary factor affecting ductility is the amount or weight of the confining reinforcement used.
Concrete Laboratory (U.S.)Engineer Research and Development Center (U.S.)
Concrete beams; Confining reinforcement; Ductility; Reinforced concrete
Technical report (U.S. Army Engineer Waterways Experiment Station) ; C-69-5.
Approved for public release; distribution is unlimited.