H.R. Vosoughifar - Assistance Professor of Civil Engineering Department, Azad University Tehran South Unit
M.R. Adlparvar - Assistance Professor of Railway Engineering Department
J. Motamed BSc (Lon)

In this paper identification the location with potential for seismic hinges and recommended for using spiral shear reinforcement for these area was evaluated. Ties and spirals provide shear resistance, if needed. They also provide lateral support to the slender longitudinal reinforcement rods and prevent them from buckling. Ties and spirals confines the concrete core, imposing triaxial compressive stresses on the concrete, hence increasing the longitudinal compressive strength of the concrete and the ductility of the elements. As the observed on Bam earthquake the most concrete building collapsed by shear failures in special region. The identification this region of structure is very important. If this regions identification very carefully, designer can apply the spiral shear reinforcement at these area. In this case the potential of shear failure reduce very among. Framed structures indented to survive an earthquake are rather different from those designed merely to withstand static loading. The latter might well have deep beams and comparatively narrow columns- but in the strong lateral motion imposed by an earthquake plastic hinges would then form in the columns leading to complete collapse. From observation of performance in earthquakes, the Strong Column/Weak Beam concept has how become fairly standard. This requires an increase in the column size relative to the beams, and more attention to reinforcement detailing. The intention is that under strong lateral earthquake motion, plastic hinges form in the beams adjacent to the column (except at the bottom where further special detailing is needed).

Plastic hinges, Earthquake, Column, Spiral