Title: Stiffness Modifiers for Diagonally Reinforced Coupling Beams

Author(s): Sergio E. Godínez, Theresa L. Richards, and José I. Restrepo

Publication: Structural Journal

Volume: 118

Issue: 6

Appears on pages(s): 215-224

Keywords: coupling beams; cracking; effective stiffness; seismic design; shear deformations; stiffness modifier; Timoshenko beam; truss model

DOI: 10.14359/51732848

Date: 11/1/2021

Abstract:
Stiffness modifiers are used in linear structural analysis programs to account for the development of cracks in concrete and the bondslip of steel reinforcement. In seismic design, the relative reduction in stiffness caused by cracking and bar bond-slip affects the global and local deformations of the structure and the internal force distribution in the elements, which are ultimately required in the design. This paper discusses a truss model and a statistics-based approach to determine the effective stiffness of diagonally reinforced coupling beams. The model is validated with experimental data found in the literature, showing excellent predictability capacity. Statistical optimization of the data set was performed to propose two simplified equations for the stiffness modifier intended for design.