BEARING CAPACITY OF ARCH BRIDGE STRUCTURE MADE OF CORRUGATED METAL UNDER UNSYMMETRICAL LOADING

Abstract

The issue of the scheme of work and simplified practical calculation of arched bridge structures made of metal corrugated structures (MCS) under asymmetric loading is considered. This is especially relevant in the case of a small height of the roadembankment above the top of the structure and a relatively large (for such structures) span. That is, when the load from the vehicle acts only on part of the length of the arch span. The scheme of operation of an arched bridge structure is considered under the conditions of a flat problem – for an arch of unit width, "cut out" from the vault in its most loaded part.The rod calculation model and the finite element method (FEM) were used for the calculation. On the example of the calculation of a structure in the form of a semi-circular arch from MCS, the diagram of the movement of the arch under asymmetric loading is shown. It is shown, in particular, how the values of the deflection are related to the movements of the arch towards the ground and the scheme of the formation of the elastic resistance of the ground. The limit state of the "building – soil" system is the achievement of the arch deflection, exceeding which dangerous local subsidence of the surface of the road surface above the building is possible. To determine the fate of the external load, which is perceived only by soil resistance, the arch is taken as a "mechanism" made of hard disks, which are connected by hinges in places of concentration of deformations and stresses. At the same time, the geometric immutability of such a "mechanism" and the static balance of the "building – soil" system is provided by an  additional connection – a rod simulating the elastic resistance of the soil. The force in this rod is taken as the value of the equivalent elastic resistance of the soil at the permissible value of the arch deflection. The magnitude of the external load,  which is perceived only by the resistance of the soil, is considered as permissible, if at the same time the deflection of thearch remains within the permissible limits.