INTERNATIONAL CONTEST | SHEAR PREDICTION IN A 2m DEPTH BEAM
I+D+i | Reinforced Concrete
Horvital Project | gCons - CITEEC - Universidade da Coruña
Last Wednesday 29th of January, the shear resistance test of the biggest shear reinforced concrete beam tested on an European laboratory, within the HORVITAL project, was held by Construction Group (gCons) of the University of A Coruña (UDC) on the facilities of the Centre for Technological Innovation on Building and Civil Engineering (CITEEC), whose cutting-edge facilities made possible to achieve this milestone. Dimensions of Tested beam were 12 m long, 2 m height and 24 cm width.
The aim of the test was to search empirical evidence of the so called “size effect” on tall beams. It is well known, endorsed by practice, that common standards suppose a shear capacity for tall beams above their real value. Due to the fact that this will imply an unsafe design, usual practice tends to increase the amount of steel and concrete used on beam manufacturing, which is an impractical solution from environmental point of view. That is the reason why HORVITAL project aims to adjust the standards to the real behaviour of tall beams through a set of tests, optimizing therefore the use of materials and safety of this kind of structures.
Parallel to the test planning, gCons itself launched an international contest challenging everyone interested to predict the load that will cause breakage of the tested beam. From Neikō Ingeniería we accepted the challenge. We proposed a finite element model (FEM) that will simulate the concrete plastic behaviour, along with the reinforcement steel. For that, we relied in various academic documents (such as papers, thesis, etc.) on which plastic behaviour on concrete is studied and models for simulation of it on calculation software are proposed. After obtaining the stress-strain curves and the plastic damage parameters for the concrete used on the beam manufacturing, this data was set into the FEM model. Once beam was discretized on its corresponding calculation elements, a displacement-controlled test was held on the calculation software. Descending of the bearing plate was forced downwards, loading this way the beam on the contact between both. Crack location was evidenced by the appearance of plastic damage on the FEM model.
Once the test on the CITEEC laboratories was held, the results given from our FEM model seem to be quite accurate, at least regarding to the beam capacity (the only test result published on the moment of this publication). Load transmitted from the bearing plate to the beam at breakage of our FEM model was of 960 kN, while real test reached 973 kN.
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