Uncertainties in Performance Estimates Of Reinforced Concrete Columns

Abstract

I assembled a reinforced concrete column test database and describe its layout. This database can be used by researchers and practicing engineers to establish the magnitudes of uncertainties involved in performance estimates of reinforced concrete columns. I wrote a program in Mathematica that uses ACI methods to determine shear and moment capacities for 168 columns from the database, and I compare these predicted capacities to the measured values. The average value of the maximum measured moment divided by the predicted moment capacity was determined to be 1.22, while the ratio of the maximum measured shear to the predicted shear capacity was determined to be 1.50. The sensitivity of the ACI methods to various parameters (e.g., amount of steel in the column, magnitude of axial force) is also examined. Comparison of the test data with ACI predicted moment capacities shows that as the axial load increases with respect to the compressive strength of the concrete, the ACI code becomes more conservative in predicting moment capacities. Comparison of the test data with ACI predicted shear capacities shows that as the ratio of the length of the column to the column’s depth increases, the ACI code becomes less conservative in predicting its shear capacity. In addition, the ACI code becomes more conservative as the longitudinal steel ratio increases.