THE CALCULATION OF DEFLECTIONS OF FLEXIBLE REINFORCED CONCRETE ELEMENTS TAKING INTO ACCOUNT THE LONG-TERM EFFECT OF EXTERNAL LOAD
DOI:
https://doi.org/10.31713/budres.v0i43.12Abstract
The article analyzes the existing methods of determining deflections of bending elements taking into account long-term processes. It is noted that the main factor affecting the deflections of the elements over time is the creep of concrete. With prolonged action of loads due to concrete, creep of the compressed zone of concrete, the neutral line moves towards the stretched section zone, the stresses in the compressed concrete decrease, and the stresses in the reinforcement increase, while the deflections of the elements increase.
Based on the analysis of the results of calculation of deflections of flexural elements taking into account the duration of the load, it was established that the method of determining deflections according to Eurocode 2 significantly underestimates the influence of concrete creep, and the DSTU method overestimates it. It is suggested that, taking into account the influence of concrete creep, it should be based on the change in the stress-strain state of the cross-section over time, and the deformation of the extreme compressed fiber of concrete should be determined using the creep coefficient and the coefficient of completeness of the stress diagram in compressed concrete. The proposed formula for determining the coefficient of completeness of the stress plot based on the deformation method, as well as the improved method for determining the curvature and deflections of bending elements based on this method. In the article, the study of the influence of concrete creep on the deflections of flexural elements was continued with the simultaneous conduct of experimental studies using modern materials. The calculations were performed in relation to the article "Improving the calculation of deflections of flexible reinforced concrete elements taking into account the long-term effect of external load".
