Geometric and material nonlinear analysis of reinforced concrete slabs using assumed strain elements

Abstract EN

The finite element method is used for the nonlinear analysis of reinforced concrete slabs.

Nine-node Lagrangian degenerate elements, which arc the general shear deformable elements, have been employed.

An assumed transverse shear strain is used in the formulation to overcome the shear locking.

A layered approach is adopted lo discrctizc the concrete through the thickness.

Both an elastic perfectly plastic and strain hardening plasticity approach have been employed to model the comprcssivc behaviour of the concrete.

The yield condition is formulated in terms of the first two stress invariants.

The mol ion of the subsequent loading surfaces is controlled by the hardening rule, which is extrapolated from the uniaxial stress-strain relationship defined by a parabolic function.

Concrete crushing is a strain-conlrollcd phenomenon, which is monitored by a fracture surface similar lo the yield surface.

Steel reinforcement is smeared through the concrete layers and assumed to have similar tensile and compressive stress-strain relationships.

Geometrical non linearity in the layered approach is considered in the mathematical model, which is based on the total Lagrangian approach taking into account Von Karman assumptions.