REINFORCEMENT OF LONG CYLINDRICAL SHELL WITH STEEL FIBER

Abstract

A technique for experimental study of long cylindrical shells is proposed in order to determine their stress-strain state, load-bearing capacity and crack resistance. To implement the task, the authors developed a special stand. For testing, eight models of a cylindrical shell were made ― 4 made of reinforced concrete and 4 made of fiber-reinforced concrete. Fiber-reinforced concrete shell specimens have additional dispersed reinforcement with steel fiber with bent ends in the amount of 1% by volume of concrete. Simultaneously with the shell samples, control samples of prisms and cubes were made to determine the physical and mechanical characteristics of concrete. Experimental and control samples were kept in the same temperature and humidity conditions for 28 days at a temperature of 16 ... 20º. To determine the physical and mechanical characteristics of concrete in each series, six control cubes 100x100x100 mm in size and three prisms 100x100x400 mm in size were tested. Tests of control samples were carried out according to DSTU B V.2.7-214:2009. Based on the results of these tests, it was established that the concrete of the shell specimens is represented by the C20/25 class in terms of compressive strength. The paper presents the results of testing a fiber-reinforced concrete cylindrical shell, the thickness of which is 45 mm. The shell was hinged at four points and loaded with a vertical distributed load applied in four strips, each 13 cm wide, and only along the body of the shell. Tests showed that the bearing capacity of the shell was 128.6 kN, and the first crack was formed at a load of 64.3 kN, which is 50.0% of the bearing capacity. Until the moment of loss of bearing capacity, 10 cracks were formed in the shell with the same initial opening width of 0.05 mm and a maximum final opening width of 0.7 mm. Computer simulation of the shell and calculations were performed using licensed software ANSYS 17.1. The bearing capacity determined in ANSYS was 120.2 kN, which is 6.5% less than in the experiment. The test methodology and the developed stand are universal in nature and will be used for further research.