SLENDER COLUMNS IN HIGH STRENGTH CONCRETE AND NORMAL STRENGTH CONCRETE: BS 8110 AND EC2 COMPARED

Eighteen large-scale reinforced concrete columns, with concrete compressive strength of 55.24N/sq mm or 76.15N/sq mm, were tested under short-term loading. The effective-length-to-depth ratios of the columns are 25.2, 28.7 or 30.4, load-eccentricity-to-depth ratio is 0.25 or 0.50, and steel ratio is 3.35% or 5.24%. The experimental behaviour of the columns is presented and discussed. Also, the tested failure loads are compared with those values predicted by BS 8110 and EC 2. Generally, EC 2 is more conservative than BS 8110. While both Codes tend to give smaller safety margins for column capacity as eccentricity increases, BS 8110 could be unconservative for large eccentricities. Both Codes appear to be more conservative for slender columns of higher strength concrete. Predictions of column capacity by EC 2 are close to values from a non-linear analysis by a P-delta method. (A)