Impact of low-cycle loads on deflections and width of crack opening of concrete beams with different types of reinforcement

The article presents the studies of the impact of low-cycle loads on experimental samples of concrete beams with different types of reinforcement – unstressed steel bars; steel pre-stressed reinforcement and unstressed reinforcement (mixed reinforcement); basalt-plastic reinforcement. Influence of low-cycle loads on the width of cracks opening and deflections of concrete beams were established. The research results of beams with steel reinforcement without pre-stressing, with pre-stressing and the beams with basalt-plastic reinforcement have shown interrelated proportional relative increase of the width of cracks opening and increase of deflections. Suggestions for consideration of the impact of low-cycle loads during the calculation of bending concrete beams reinforced with steel or basalt-plastic reinforcement by the second group of limit states were proposed. Coefficients determined experimentally for calculating the deflections and the width of cracks opening of the beams were introduced into the equation. Taking into account the impact of low-cycle loads during the calculation of bending concrete structures reinforced with steel or basalt-plastic reinforcement will provide higher reliability of such structures performance. (paper)