Скінчено-елементний аналіз пошкоджених балок, підсилених фібробетоном

Abstract

The results of the study of damaged reinforced concrete beams of rectangular cross-section reinforced with fiber concrete are considered. Previously, experimental studies of beams damaged in the stretched or compressed zone, reinforced with steel-reinforced concrete, were carried out. First, the theoretical value of the load-bearing capacity of a reinforced concrete beam without damage was determined using various existing methods, and then its load-bearing capacity was determined experimentally. Based on the results, graphs of the change in deflections under the increasing load, graphs of the dependence of the relative longitudinal deformation on the load for the left and right support parts of the beam, as well as for the zone of its net bending, were constructed for each sample. At the next stage of research, the bearing capacity of two groups of reinforced beams was determined. The first group consisted of three samples with compression zone damage; the second group had two samples with damage in the stretched zone. In addition to the bearing capacity, deflections and relative longitudinal deformations are determined for each sample. Modeling and calculations were performed for five samples of reinforced beams with variation of the damage zone and its volume. In all calculations, the load was considered in the form of two concentrated forces applied symmetrically. Computer modeling and numerical analysis of damaged beams using the finite element method were performed in two computer programs ― Robot Structural Analysis and LIRA-SAPR. The maximum deflections and stresses are determined. A comparative analysis of the obtained results with the results of experimental studies was carried out. It was established that the deflections obtained as a result of calculations in the two programs are practically the same. And the tensions are somewhat different. The maximum difference in stresses is observed for the ZBP1 sample ― 11.8%. For four other samples, it is approximately the same, and on average it is 5.8%. Comparing the results of calculating the maximum stresses in LIRA-SAPR with the results of experimental studies gives a maximum discrepancy of 5.85%. And the biggest discrepancy occurs in the deflections ― here it fluctuates in the range of 19.0÷19.2%.