RELIABILITY OF SHORT AND SLENDER REINFORCED-CONCRETE COLUMNS

Reliability indexes associated with typical short and slender columns are evaluated. Designs are made in accordance with ACI 318-89 and Mexico City concrete design regulations. Loads associated with ACI 318-89 designs are taken from ASCE 7-88. The Monte Carlo simulation technique is used for the analysis. A general view of beta indexes relative to different limit states (obtained previously by the first writer) is presented. The study is extended to beta indexes relative to slender columns. It is shown that slender columns subjected to loads with small eccentricity ratios present the highest beta-reliability values, with respect to other limit states such as flexure, shear, and torsion. In all cases, RCDF-87 beta values are higher than those associated with ACI 318-89. This is due to the following reasons: (1) The probabilities of exceedance of the maximum loads adopted for both codes are drastically different; (2) the codes define the concrete strength with different reduction factors; and (3) load and strength factors differ for both regulations.