Title:
Fiber Beam Element Formulation Using
the Softened Membrane Model
Author(s):
R.T. Mullapudi and A.S. Ayoub
Publication:
Symposium Paper
Volume:
265
Issue:
Appears on pages(s):
283-308
Keywords:
fiber model; force-based finite element; shear critical; softened membrane model; Timoshenko beam.
DOI:
10.14359/51663300
Date:
10/1/2009
Abstract:
This study presents an inelastic nonlinear beam element with axial, bending, and shear force interaction for cyclic analysis of reinforced concrete (RC)
structures. The element considers shear deformation, and is based on the section discretization into fibers with hysteretic material models for the constituent materials. The shear mechanism along the beam is modeled by using a Timoshenko beam approach. The steel material constitutive law is assumed to be bilinear. The concrete constitutive law is based on the soften membrane model. This newly developed constitutive law can predict the concrete contribution Vc, which is produced by the shear resistance of concrete along the initial crack direction. The constitutive relationships
of the RC element have been developed based on the smeared behavior of
cracked continuous orthotropic material assumption of concrete with the inclusion of Poisson effects. This model accounts for the softening effect of concrete, as well as the tension stiffening and confining effects. Transverse strains are internal variables determined by imposing equilibrium at each fiber between concrete and vertical transverse steel reinforcement. Element forces are obtained by performing an equilibrium-based numerical integration on the section axial, flexural, and shear behaviors along the element length. The paper concludes with a correlation study between the analytical models and experimentally tested shear-critical RC columns.