pullout forces. This has been the subject of considerable experimental and numerical research. Design recommendations are normally based on empirical equations or on upper bound plasticity solutions, which usually overestimate pullout forces, leading to conservative design. Experiments on Bond Behavior…
pullout forces. This has been the subject of considerable experimental and numerical research. Design recommendations are normally based on empirical equations or on upper bound plasticity solutions, which usually overestimate pullout forces, leading to conservative design. Experiments on Bond Behavior in Curved Bars Bars are often bent through angles of up to 90° to meet geometrical constrains imposed by section depths. In such situations the transverse stress on the concrete, and in the stress concentrations, secondary cracking and concrete damage in the region of the bend, are more complex than that experienced in straight bars. If bent bars are to be properly designed, suitable criteria have to be developed and degradation of ultimate strength and stiffness cyclic loading should be predictable. Fundamental experimental data on the pull-out behaviour of wrved reinforcing bars subjected to monotonic and cyclic loading regimes, designed to follow a typical earthquake loading history, have been obtained at Glasgow University [1, 2]. These include strain and stress distributions within the reinforcement, and bond stress distributions along the bar/concrete interface. Factors such as the influence of embedded length degree of curvature, bar diameter and bar type have been investigated. Specimens, illustrated Fig 1, were tested in a 2000 kN uniaxial servo-controlled ... ..., .............. ,,I"-. machine using a ramp generator manually.