Experimental studies of crack resistance of unit sof monolithic frames and continuous beams with curved reinforcement stressed on concrete

Abstract

The purpose of the experiment is to study and compare the stress-deformation state of the nodes of monolithic continuous beams without prestressing reinforcement and with curvilinear tension reinforcement (with different angles of inclination) under short-term loading, loaded by two concentrated forces equidistant from the support.

The design of the samples allows for analyzing the stress-strain state, the process of crack formation, and the load-bearing capacity depending on the different angles of inclination of the prestressed reinforcement with tension on the concrete (without adhesion to the concrete).

In the course of the experiments, the nature of cracking and destruction of the samples was investigated in detail. At each stage of loading the samples, the appearance of the first cracks was recorded visually, as well as with the help of strain gauges (and indicators).

During the study of the crack resistance of the experimental samples, it was established that the force of crack formation, as well as the nature of the development of cracks in all series of samples, is different.

Thus, in samples without prestressed reinforcement, a rather rapid appearance of a critical crack was observed, which subsequently developed and led to the destruction of the samples.

In the samples with curved tension reinforcement, with the angle of inclination of the reinforcement α=6º, the appearance of the slope of the crack was recorded at fairly late stages of loading and subsequently led to the sudden destruction of the samples.

In the samples with curved tension reinforcement, with the angle of inclination of the reinforcement α=13º, a whole system of inclined cracks was recorded, which also appeared at the late stages of loading, but critical cracks appeared suddenly and led to destruction.

According to the results of experimental studies, a comparative analysis of the average values of crack opening widths for samples without prestressed reinforcement and samples with curvilinear stressed reinforcement (with different angles of inclination) was obtained