STRESSED-DEFORMED STATE SEPARATE PERFORATED BEAMS NEAR INTERMEDIATE SUPPORTS UNDER THE ACTION OF A SYMMETRICAL LOAD IN THE SPANS

Abstract

Data on the stress-strain state of various types of intermediate supports of two-span continuous perforated beams with a height of 300 to 900 mm were obtained as a result of their calculation by the finite element method in the "Lira" software complex under the action of a load symmetrically distributed evenly in the spans. Beams of the above heights, obtained from the original I-beam beams with a height of 200 to 600 mm, respectively, by developing their cross sections with the coefficient

It was found that the design of the intermediate support for beams of different heights significantly affects the maximum deflections in the beam span and stresses in the support cross-sections of the beams. The smallest deformations and stresses were recorded for the most rigid support with welded holes to the left and right of the support and a supporting transverse stiffening rib, and the largest – for the least rigid support with non-welded holes in the absence of a supporting rib.

The presence of high values of the reduced stresses in the calculated point 11 of section 3–3 for perforated beams with a height of 750 and 900 mm requires the development of special constructive measures in order to reduce these stresses to certain values, that do not exceed the calculated resistance of the accepted steel class. One of the ways to ensure the load-bearing capacity of such beams according to the limit states of the 1st group can be the use of high-strength steels of a class not lower than C390.

The analysis of the obtained values of the tangential stresses shows that they are the largest in point 11 of section 3–3, that is, directly on the support, but none of them exceeds the value of the calculated resistance of the steel.

Since the real operation scheme of a two-span continuous perforated beam near the intermediate support differs to some extent from the ideal design scheme due to the presence of elements and details of its fastening to the lower supporting structures, there is a need to conduct experimental studies, which will make it possible to develop a calculation methodology taking into account numerous factors. which affect the bearing capacity of both the support itself and the beam as a whole.