Keywords

Abstract

Global ductility;

 Framed RC buildings; 

Seismic action;

 Directionality

This study examines the influence of ground motion directionality on global ductility μs of framed reinforced concrete structures. Suitable values of angle of attack θ, longitudinal reinforcement ratio ρl, dimensionless axial stress υ and mechanical ratio of transverse reinforcement ωwd were assumed. Detailed nonlinear modeling was adopted to reproduce the behavior of reinforced concrete elements in the plastic field considering, also, the confinement effect on concrete mechanical properties. Nonlinear static simulations were carried out with the capabilities of the OpenSees code to evaluate the capacity curves and the corresponding global ductility. The results show that plastic hinges develop on the columns for the combined effect of bending moments transmitted by the beams framing into the same joint for values of the angle θ equal to 30° and 45°. Consequently, the formation of soft-storey mechanisms significantly reduces the global ductility μs. A design formula is proposed to avoid such collapse mechanism for framed reinforced concrete structures in ductility class high.

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