stress-strain state

This study reviews the current state of research and limitations on the fatigue strength of web-flange connections in steel runway beams for overhead cranes. It evaluates key factors influencing fatigue strength, including stress-strain behavior, notch classifications, and various web-flange configurations (welded, rolled, combined). The research stresses the need for accurate fatigue life assessments, particularly for both new and older structures built with simplified standards.

This article presents a comparative analysis of the nonlinear behavior of a reinforced concrete beam with damaged reinforcement in the tension zone under a gradually increasing load until failure. The experimental beam, measuring 2100 mm × 200 mm × 100 mm, consists of a 20 mm diameter rebar in the tension zone, two 6 mm diameter rebars in the compression zone, and 6 mm diameter stirrups spaced 75 mm apart for transverse reinforcement. Nonlinear calculations were performed using ANSYS and LIRA-SAPR, with identical initial conditions applied to both models for accurate comparison.

The article analyzes defects and damage in reinforced concrete structures, particularly physical, biological, and chemical, with an emphasis on the impact of prolonged operation and aggressive environmental conditions. Research shows that mechanical damage, such as spalling and potholes, significantly reduces the load-bearing capacity of structures and causes complex deformations.

Due to today's conditions, it is necessary to reconsider the purpose of buildings and structures that use a significant number of reinforced concrete elements subjected to complex stress-strain states. The researchers are faced with the task of determining the residual bearing capacity of an element with uneven damage, which will allow choosing the most optimal option for calculating and selecting materials.

Currently, on the world market, there are trends in the construction of a large number of monolithic and prefabricated reinforced concrete structures, and individual parts of these structures are operated with damage or defects, and the causes of these damages are quite diverse. In modern conditions, such work can be facilitated and analyzed in more detail with the help of specialized software, which can include all the necessary characteristics of material behavior and include existing defects or damage.

Machining difficult-to-cut materials, which include most high-alloy chromium-nickel steels and alloys, requires optimization of cutting parameters, correct application of tool materials, cutting blade geometry, etc. The particular relevance of a scientifically based analysis in addressing these issues is due to the large costs incurred in machining products made from such materials. The possibilities of experimental research to provide correct technological recommendations are quite limited.

In this article, a new method of increasing the efficiency of combined steel roof trusses is proposed and considered. A rational shape of the steel roof truss, including its topology and rational geometric parameters, was obtained, but without obtaining a rational SSS. A proposed method provides the adjustment of SSS in the truss by changing the upper belt panel length. On the basis of the obtained rational SSS of the combined truss, a new structural form is proposed.