INCREASING THE CRACK RESISTANCE OF CYLINDRICAL SHELLS THROUGH ADDITIONAL DISPERSED REINFORCEMENT

The results of experimental studies of long cylindrical shells are considered in order to assess the cracking of a reinforced concrete cylindrical shell with its additional dispersed reinforcement. The developed design of the test stand allows transferring a vertical load to the shell, evenly distributed over four strips, which were at an equal distance from each other. 4 models of a cylindrical shell made of reinforced concrete (samples RC1-RC4) and 4 models of a cylindrical shell made of fiber concrete (samples FRC1-FRC4) were manufactured and tested. The thickness of the samples was 45, 50, 55, 60 mm, and the cross-sectional dimensions of the side elements changed accordingly. The distributed load (vertical) was applied over four strips, 13 cm wide each, and only by the shell body, i.e. the side elements were not loaded. The shell is hingedly supported from the corners on 100x100mm plates. In each of the three zones located between the load chains, 4 watch-type indicators are fixed. In addition to the indicators, strain gauges are glued to the shell, with the help of which deformations on the upper and lower surfaces were monitored. Graphs of the dependence of relative deformation on the load were constructed. The bearing capacity of the shells and the load at which the first crack formed were determined. By the time the bearing capacity was lost, cracks with the same initial opening width of 0.05 mm had formed in all shells. The final width of the crack opening, like the bearing capacity, increased slightly with increasing shell thickness. The load at the beginning of crack formation turned out to be the largest for two average values of shell thickness – 50 and 55 mm. The general picture of crack formation of all samples is almost the same.