Analysis of the calculated relation for evaluating of the strength of bent reinforced concrete elements with circular shape of cross-section under the action of shear forces

Introduction. Current Russian codes of design of reinforced concrete elements do not have rules and considerations for analysis of bent and compressed elements with irregular (not similar to rectangle) shape of cross-section under the action of shear forces. As result of previous investigations which were conducted in Research Institute of Concrete and Reinforced Concrete (NIIZNB) named after A.A. Gvozdev, new method of evaluating of the bearing capacity of inclined cross-section was proposed. Developed method has good matching with the results of experiments, conducted by Russian and foreign researchers. This paper deals with comparison of results of experiments with analysis by proposed model.

Aim. Further improvement of methods of analysis of strength of inclined sections of bent and compressed elements with irregular (not similar to rectangle) shape of cross-section under the action of shear forces. Comparison of proposed model with available data of experiments and results of numerical analysis.

Materials and methods. Theoretical investigations have been conducted on base of results of experiments, conducted earlier by Russian and foreign researchers for elements with circular cross-section. Totally, analysis has been performed for 13 samples with circular crosssection.

Results. Quality analysis of results of experiments and considerations of foreign codes has been conducted. Method of calculating of bearing capacity of bent reinforced concrete member with circular cross-section has been proposed. As a result of provided comparison of proposed method with data of experiments it was found out that proposed method provides required level of reliability – average rate of experimental bearing capacity to calculated value is 1.241 with standard deviation 0.123. It has been stated, that maximum deviation of results of calculation by proposed model was observed for samples with higher strength of concrete. As a result, it was recommended to provide additional investigations of samples with high strength of concrete, i.e. High Strength Concrete (HSC) samples (with strength greater than 60 MPa).

Conclusions. Method for calculating of the bearing capacity of bent reinforced elements under action of shear forces by the sloping crack has been proposed. When developing the methodology, continuity with current Russian regulatory documents in the part of elements with rectangular cross-section was taken into account. Proposed model has been checked with available results of experiment (totally 13 experiments of different authors). According to conducted evaluating of results of experiments proposed model provides enough reserve of reliability. To additional checking of reliability of high strength concrete members, it was recommended to provide additional experiments, I.e. for high strength concrete members.

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