Experimental investigation and modelling of reinforced concrete ties subjected to short-term and long-term loads

Eugenijus Gudonis

Doctoral dissertation

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Application of high strength concrete and reinforcement has resulted in longer spans and smaller depths of structures. Therefore, the condition of the limiting deflection rather than the strength requirement often is the governing design criterion. In structural analysis civil engineers can choose between traditional design code methods and numerical techniques. In order to choose a particular calculation method, engineers should be aware of accuracy of different techniques.

Complicated stress state in reinforced concrete (RC) structures is caused by creep and shrinkage effects of concrete, which strongly depend on continuously changing environmental conditions. Shrinkage and creep of concrete are considered as long term effects, though they are of a great importance not only for long term deformations of RC, but also for short term deformation and cracking analysis. Interaction between reinforcement and concrete is one of the most important effects governing the cracking process of RC. Due to insufficiently defined calculation methods of concrete deformation, cracking, shrinkage and creep of concrete, design of RC structures using code methods becomes unreliable. Employing the Eurocode design methods significant errors should be considered while calculating short term deformations of tensile RC members (especially during the initiation of cracking). Though for long term deformation analysis Eurocode methods adequately predict the limit values, the distribution of deformations is not clearly defined.

In present study a stress–strain and cracking analysis of tensile RC elements under short and long term loading is performed. Experimental data of deformation and cracking process of tensile RC elements under short and long term loading is presented.

The current study presents the improved Eurocode calculation method for the prediction of short-term deformations of RC members under tension. The proposed modification allows to determine short-term deformations evaluating the shrinkage effect occurring prior to the external loading. A relationship 
between long-term strains and time is proposed, presenting a detail development of deformations from the constant loading to the limit value.

Accuracy analysis of Eurocode design method for the prediction of average strains has been performed. It was shown that in the preloading stage, the evaluation of shrinkage and creep effects improves the method accuracy.

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DOI: https://doi.org/10.20334/2290-M

Book details

Data sheet

Year:
2014
ISBN:
978-609-457-739-0
Imprint No:
2290-M
Dimensions:
145×205 mm
Pages:
146 p.
Cover:
Softcover
Language:
Lithuanian
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