PSI - Issue 59

Volodymyr Romanіuk et al. / Procedia Structural Integrity 59 (2024) 471 – 478 Volodymyr Romanіuk et al. / Structural Integrity Procedia 00 (2019) 000 – 000

472

2

Keywords: continuous beam; intermediate support; section; perforation; stress; deformation; bearing capacity; software complex.

1. Introduction The current standards for the design of steel structures (DBN V.2.6 – 198:2014, 2014) briefly present the general principles of the design of perforated beams, give formulas for calculating stresses at characteristic points of the cross-section with the hole, and emphasize the need to strengthen the cross-section at the support with transverse stiffeners. In all other aspects, perforated beams are subjected to the same requirements as ordinary rolled beams. At the same time, this standard these standards predominantly address single-span beams, with no specific considerations provided for the design nuances of multi-span continuous perforated beams. European design standards currently do not regulate the calculation of perforated elements (Eurocode 3, 2005). There are numerous experimental and theoretical studies on the bending perforated elements performed by both domestic and foreign scientists, but they do not answer all the questions related to the features of the calculation and design of multi-span continuous beams . For these structures, a crucial factor influencing their load-bearing capacity – beyond considerations of magnitude, nature of action (static or dynamic), type of load (concentrated, evenly distributed, combined), load action scheme, material strength (standard or high-strength steels), span values, and geometric parameters of the cross-section – is the structural design of the intermediate support part of the beam. During studies of the load-bearing capacity of a prestressed arch specific aspects of the behavior and the stress strain state of the upper belt of the arch, constructed of a perforated I-beam operating according to the continuous scheme of a two-span beam due to the presence of an intermediate support in the form of a prestressed spacer , were clarified. The findings led the authors to the need to conduct additional comprehensive experimental and theoretical studies of the section of the bending element near the intermediate support. At the first stage, it is recommended to use the "Lira" software complex which is widely used in the practice of designing various building structures and which has confirmed its high efficiency and accuracy during the study of perforated beams of a Z-shaped profile. Some aspects of the bearing capacity of structures using perforated elements are considered in other articles (Romaniuk et al., 2021, 2023). 2. Variants of design solutions for intermediate supports The modeling of a perforated continuous beam (Fig. 1) with an I-beam cross-section was performed using the “Lira” software complex based on the finite element method . The underlying principle of this method lies in the ability to approximate any continuous quantity through a piecewise-continuous function, constructed in real dimensions with all structural features represented at a finite number of points.

Fig. 1. Model of a continuous perforated beam in the “Lira” software complex.

To build a discrete model of the perforated beams with hexagonal holes, the following conditions are established: 1) the region under investigation is divided into a finite number of elements, sharing common nodal points to approximate the overall shape of the area; 2) nodes within the considered area are fixed; 3) values at the central points of the domain are determined by the approximating function of the continuous quantity under investigation at nodal points.