FIG. 6 ) STRESS-STRAIN RELATION (STRAIN MEASURED ON THE 55cm OF THE COLUMN LENGTH ).

Table (3) shows the values of αc) for each specimen and the values of (K) due to the previous equation. By using the fitting curves, the relation between (K) and the confinement α c) can be expressed as the following equation: K=(3.5+αc)/(1.0+5.50% αc). The USSR code(9) gives the following relation between (K) and the confinement (αc): K=(5.0+αc)/(1.0+4.50*αc)

From Figure (9), it can be seen that the relation between (K) and the confinement (αc) given by the USSR code(9) and that derived in this work have the same character.