THE MODELLING OF STRESS STREIN STATE OF OVERPASS PIERS WITH A HOLE FOR VEHICLE PASSAGE FOR THE RATIONAL DESIGN

Abstract

In the paper have been described a principled rational design solution for overpass piers, which must have the possibility of
through-passage for vehicles through the piers, as a result of the complex urban planning situation, characteristic of the dense
construction of typical regional and district cities of Ukraine. Thus, the pier have to simultaneously perform the function of
maintaining the span structure of the overpass, and also ensure the technological possibility of laying at the level of the base of
the pier of the roadway. Have been considered several basic constructive options for the arrangement of passage piers, which
are arranged on weak soils. Have been analyzed the advantages and disadvantages of each. Among the selected options have
been chosen the most rational one in the form of a monolithic P-shaped frame structure on the base of pile foundations, united by
a solid slab grid. Have been also presented method of selecting the geometric parameters of the main structural components of
such pier. The proposed engineering solutions were illustrated on the example of the designed overpass in the Vinnytsia city.
Have been developed a fragment of the general plan of the overpass and the architectural form of the pier with a passage in the
form of a spatial -shaped frame for this example. Have been carried out the selection of rational geometric parameters of the
proposed architectural form taking into account the rules of traffic according by the described method. Have been developed a
3D-model of the specified architectural solution of the pier with a passage using the finite element method by standard software
Lira-SAPR. Have been evaluated the most dangerous combinations of loads, which include technological effects on the structure
at the level of the span of the overpass structure and at the level of roadway along the body of the support foundations. Have
been analyzed the stress-strain state of the pier. Have been performed preliminary strength calculations for the developed model
of the road pier and have been determined the most dangerous cross-sections, in which the maximum force and bending moment
factors operate. Have been proven that the most loaded structural elements of the passage pier are the crossbar system that
supports the span structure of the overpass, due to the large distance between the support posts, as well as the foundation
structure, due to the horizontal components that arise during the movement of vehicles.

The performed design job confirm, from the point of view of strength and stiffness, the principle possibility of arrangement and
the rationality of the selected structural solution of the pier with the passage.