PERFORMANCE CHARACTERISTICS OF CONCRETE MEMBERS REINFORCED BY PLAIN BARS

In an experimental program, five beams and columns reinforced by plain bars have been tested under cyclic and monotonic load. The specimens are built in half scale and lack sufficient stirrups. The tests indicate that a similar pattern of cracking governs all beams and columns. Under increasing load, an initially stiff and relatively linear response occurs, but initiation of slip of longitudinal bars causes relatively brittle drop of strength. This is followed by a relatively ductile residual resistance that is accompanied by sliding of specimen over its interface with foundation and by dowel action of longitudinal bars. A limit state formula has been developed to predict residual strength of beams. The specimens show limited ductility, less than two, before reaching maximum strength, but exhibit a residual ductile behavior, with a ductility value of about 4, after brittle fall of maximum strength. Using a limit analysis model for dowel action, the residual shear strength of beams has been evaluated. The test results have been compared with recommendations of FEMA-356.

کلیدواژه ها:

reinforced concrete beams and columns ، plain bar ، cyclic test ، dowel action ، residual shear resistance