LOCAL STABILITY OF SHELVES AND WALLS OF BENDING PERFORATED ELEMENTS

Abstract

An overview of the main results of experimental and theoretical studies of domestic and foreign scientists on the problem of local stability of shelves and walls of bending perforated elements is given. The calculated preconditions, formulation of the purpose and tasks of researches, methods of theoretical definition of parameters of a stress-strain state in calculated points of cross section are considered. The analysis of the existing problems of local stability of elements of cross section of beams taking into account action of the bending moment and cross force is executed.

It is noted that the issue of determining the critical load in terms of local stability of perforated beams has not yet been resolved. In most calculations, the perforated wall was considered as a cantilever beam or a compressed column. This approach is possible to evaluate the structure only with a certain perforation geometry, which does not allow it to be applied to the structure as a whole. In the recommendations based on similar researches, the wall loaded with local loading is offered to strengthen with stiffening ribs, but there are no recommendations establishing the minimum necessary height at which these ribs will not be required.

Comprehensive experimental-theoretical studies of compressed-bending perforated elements according to the inseparable scheme, which worked as part of the pre-stressed arch, and perforated elements Z-shaped profile in oblique bending were performed at the Department of Industrial and Civil Engineering National University of Water and Environmental Engineering. As a result, new experimental data on the stress-strain state of perforated elements were obtained, which testified to the elastic work of the material at all load stages. It was found that after reaching the level of the calculated load, no visible destruction of structures was observed, and the vertical displacements in the middle of the span did not exceed the normative values. Loss of load-bearing capacity of structures occurred without their physical destruction due to loss of local stability of the shelf and wall in the upper part of the cross section with a hole in the part of the structure where the maximum bending moment occurs, which led to total loss of stability of elements from the plane.

It is concluded, that, despite the large amount of research, today there is no clear enough mechanism to take into account the local stability of shelves and walls and their impact on the overall stability of the beams, as well as their load-bearing capacity in general.

The main tasks for further research are formulated.