Reinforcing steel under cyclic static action

Summary

The main goal of this project is to determine essential constitutive relations for the nonlinear dynamic analysis of reinforced concrete structures. Additionally, standards are to be defined, guaranteeing sufficient ductility of reinforcing steel.

The ductility of reinforced concrete structures under earthquake excitation usually requires large plastic cyclic strains of the reinforcing steel, because of the relatively brittle behaviour of the concrete. Therefore, in the framework of nonlinear dynamic analysis, the constitutive relations for the reinforcing steel in these range of strain are of particular importance. Additionally, the tension stiffening effect is of interest, because the stiffness of reinforced concrete is increased, and the resulting strain peaks in the cracks influence the ductility of the steel. Furthermore, the effect of local instabilities of the steel under pressure on the ductility after a change of the direction of excitation shall be quantified by these experiments.

Static cyclic experiments with five longitudinal loaded reinforced concrete specimens have been carried out. The diameter of the reinforcment and the load history were varied. Additionally experiments with pure reinforcment steel, are under way. These experiments are carried out in cooperation with the "Eigenössische Materialprüfungs- und Forschungsanstalt (EMPA)".

Staff

Prof. Dr. Hugo Bachmann (Guideance)
Dr. Martin Neujahr