Title: Placement Errors for Reinforcing in Concrete Columns
Author(s): Robert G. Drysdale
Publication: Journal Proceedings
Appears on pages(s): 9-15
Keywords: columns (supports);computation;models;reinforced concrete;reinforcing stells;safety;stastistical analysis;strength;tests;tolerances (mechanics).
This paper providesd information on the distribution of bar placement errors and illustrates the influence of these errors in column strength. Studies of bar locations in 232 columns from 12 exsisting buildings have shown that the placement errors often exceed specified tolerances. In no cases were bars found to be missing but placement errors greater than 5 in. (12.5 cm) were encountered. Strength calculations based on actual locations of reinforcement showed individual reductions of strength greater than 15 percent and for all columns a mean reduction of nearly 5 percent for all effective eccentricites. Proabablity models to describe the distribution of reinforcing placement errors were derived to facilltiate reliablity analysis.