Behavior of RC slender columns under unequal eccentricities and skew angle loads at the ends

In the design of slender concrete columns, such as civil or architecture constructions, biaxial compression loads with unequal eccentricities and skew angles at both ends is a common situation. However, in the literature, there is a lack of experimental data subjected to this type of load both casted with normal and high strength concrete. The scarcity of experimental results prevent from calibrating numerical models and contrasting the reliability of the simplified approaches proposed in the Standards.In this paper, 36 slender columns subjected to biaxial compression with unequal eccentricities and skew angles at the ends. The following parameters have been considered in this research: concrete strength, eccentricities ratios at both ends, eccentricity value, and the combination of different skew angles.Ultimate strength and deformed shape of the columns have been analyzed. Simplified approaches proposed by EC-2(2004) and ACI-318(11) have been compared with the experimental data and conservative results have been reached with different accuracy depending on the studied parameters. Less accurate results are obtained for high strength concrete.

► Ultimate capacity of the cross section is explosive and brittle for high strength concrete columns.
► Independently of the type of failure, a spalling off the cover is observed in high-strength concrete columns.
► The maximum reduced axial load resisted by the column is not directly proportional to the concrete strength.
► Design Codes provide conservative results for this type of forces.
► Design Codes are less accurate for high strength concrete tan for normal strength concrete.