Measures of structural redundancy in reinforced concrete buildings. I: Redundancy indices

A method based on nonlinear pushover analysis is proposed to quantify the deterministic and probabilistic effects of redundancy on the strength of structural systems. Two indices, the redundancy strength index and the redundancy variation index, are introduced to measure these effects. Simplified expressions are developed and presented to calculate these indices. The redundancy strength and the redundancy variation indices are evaluated for plane reinforced concrete frames with different stories, a different number of vertical lines of resistance, and various beam ductility capacity ratios. How the member ductility capacity and the structural geometry affects the redundancy strength and the redundancy variation index is discussed.