Keywords: FEA, RC girder, concrete, non-linear, experiment, ultimate bearing capacity.

Nowadays, we can quite often see the structural elements of RC engineering structures damaged by cracks. These defects are in many cases caused by e.g. changes of utilization purposes of the engineering structures, connected with changes of loading, degradation of construction materials (reinforcement corrosion, concrete carbonation), original static calculations inconsistently carried out (omission of some loads), etc.

We can use many calculation systems to analyse damaged RC structural elements, i.e. ANSYS, ATENA, ABAQUS etc., which consider effects of material, geometric and construction non-linearities. Especially the ATENA [1] system contains material models (SBETA, microplane 4, non-linear cementitious model, 3D concrete) that very well describe the material behaviour of concrete and enable to perform the realistic simulation of the real structure behaviour in 2D and 3D analyses. Contrary to that the ANSYS system allows performing the reinforced concrete analyses only in 3D analyses using a special reinforced concrete element called SOLID65 with material model of concrete according to William & Warnke [2]. Nevertheless, it is necessary to mention that the ABAQUS system also gives a material model for analysis of RC structures, which allows us to describe the real material behaviour of concrete very well.

The article describes the design [3], construction and process of the load tests, experimental measurements and numerical modelling of the behaviour of the sample RC girders loaded by a static load to their failure.

As a part of the grant project GACR 103/02/P083 "Development of the finite elements for structural analysis from composite materials on cement base" 3 pieces of RC girders were produced including the sample bodies (for each girder set of 3 pieces of testing cubes, 3 pieces of testing cylinders and 3 pieces of testing prisms). These RC girders with the size of m (the span being 3.00m) were used to be tested by the four-point bending test with simply supported boundary conditions. The produced testing bodies were used to determine the real material characteristics of the concrete (cube [MPa] and cylindrical [MPa] strength, Young modulus of elasticity of concrete [MPa]) and the reinforcement (yield stress ).

Simultaneously to the experimental measurements there was made the deterministic numeric analysis of the sample RC girders behaviour. The numerical analyses were performed using the ATENA system - as the 2D analysis of the plane state of stress [2]. For modelling there were used the material model of concrete SBETA, which is based on the fracture concrete mechanics in tension and on the method of the fixed cracks.

1

Cervenka Consulting: "SBETA Computer Program for Nonlinear Finite Element Analysis of Reinforced Concrete Structures in Plane Stress State", Prague, 1996.

2

ANSYS Theory Reference r. 5.5, Ansys, Inc., SAS IP, Inc., Houston, September 1998.

3

ABAQUS version 6.4, "Analysis User's Manual", Volume III: Materials, ABAQUS Inc., 2003.

4

J. Pencik, "The Project of the RC Girders Loading Tests", "The Project of the of RC Girders Loading Tests Measurements", Grant Report, 2003. (in Czech)

5

J. Pencik, "Time-dependent and Materially Non-linear Analysis of Concrete Structures". In Proceedings of the Eighth International Conference on Civil and Structural Engineering Computing, Prague: Civil-Comp Press, 2002, abstract: p. 1-2, full paper: p. 1-14, ISBN 0-948749-81-4. doi:10.4203/ccp.75.110

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £135 +P&P)