Stress-strain state of three-hinged reinforced concrete frames under repeated loading
DOI:
https://doi.org/10.36910/6775-2410-6208-2025-14(24)-49Keywords:
Reinforced concrete frame, stressed-deformed state, artificial adjustment of forces, repeated loads, concrete, reinforcementAbstract
The article presents the results of the study of two-hinged reinforced concrete frames with artificial adjustment of forces under repeated loads. The results of experimental studies of the stress-strain state of U-shaped monolithic reinforced concrete frames with tightening (artificial adjustment of forces) under low-cycle load conditions are presented. The relevance of the work is due to the fact that traditional methods of calculating statically indeterminate reinforced concrete structures do not sufficiently take into account the change in the physical and mechanical properties of materials, the development of cracks and the redistribution of internal forces under the action of repeated loads. For the study, samples of frames were made in which pre-tensioning was created. The tests were performed according to the scheme of the two-hinged system and were subjected to tenfold repeated loading to the level of 0.75 Fu, after which the frame samples were loaded to failure.
The obtained results show a significant influence of low-cycle loads on the development of deformations of concrete and reinforcement, deflections and parameters of crack formation. It was established that the main part of the residual deformations is formed in the first five load cycles, after which the stress-strain state stabilizes. The formation of plastic hinges in the span and nodes of the frames was analyzed, and the limit deformations preceding the failure were determined. A comparison of two types of frames proved the effectiveness of the artificial force adjustment system: the deflection of the bolt of a two-hinged reinforced concrete frame with artificial force adjustment is 16.1% less than that of a two-hinged reinforced concrete frame without artificial force adjustment under a single load, and by 11.2% under repeated loads.
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References
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