Experimental and numerical investigation of constitutive parameters

Reinforced concrete is the most widely used structural material. Without apparent advantages (suitable for various loading conditions, different geometric-shaped structures, durability, low price and maintenance costs), concrete suffers from one main drawback – it cracks under loads. Cracking not only affects the stiffness of structure, but have a significant impact to the building durability. The water, aggressive chemical materials and gases entering into the crack, cause reinforcement corrosion and can quickly damage the building.

Cracking analysis of RC is one of the most complicated tasks in structural mechanics. Even using modern numerical methods for structural analysis, it is difficult to predict the real cracking character. The design codes, which are the most broadly used for cracking analysis, are limited to the relatively simple elements, loaded with specific conditions. On the other hand, numerical methods require extreme computational resources to perform cracking analysis. Even using sophisticated numerical simulations, the accuracy of crack width analysis is often inferior in comparison to empirically based design codes. In principle, the accuracy numerical simulations are based on the material models used in the analysis.

In present thesis author is using stress transfer algorithms for cracking and deformation analysis of reinforced concrete members. Using the stress transfer approach, the obtained results are governed by the idealization of reinforcement and concrete interaction – bond-slip model. In order to obtain reliable bond-slip relationships, an experimental program, measuring strain distribution in tensile reinforcement was carried out. Using the obtained experimental data, reinforcement and concrete interaction modelling parameters were proposed. It was shown that applying the proposed bond stress and slip model parameters it is possible accurately simulate reinforcement strain variation, predict development of cracks and deformation process of RC element.

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DOI: https://doi.org/10.20334/2017-033-M