Calculation of a fibre concrete block as a part of locally reinforced truss nodes made of square hollow sections

Introduction. Analytical and numerical study of truss nodes made of square hollow sections (SHS) with local fibre concrete filling is presented. The analysis of numerical calculation of a fibre concrete element as a beam on an elastic base as a local reinforcement of a truss node made of SHS under the action of the concentrated load from the adjacent strut is performed. The bearing capacity of a node with the direct adjacency of struts to the chords of trusses made of S+HS is almost completely determined by geometry and physical and mechanical characteristics of truss elements made of SHS. With the cross-section of the elements selected on the basis of the calculation of the bars, the load-bearing capacity of K-type connections may not be ensured. In this case it is possible to change the dimensions of the cross-section of a truss node made of square hollow sections. In the existing Russian normative documents, there is no data on the calculation and design of reinforcement of truss nodes made of square hollow sections by filling with concrete. In this connection, it is important to develop simple and reliable methods of strengthening such nodes, as well as appropriate methods of their calculation. The purpose of the work is to develop a methodology for calculating the fibre concrete block of analytical dependencies to determine the bearing capacity under concentrated load.

Materials and methods. The research method based on the numerical modelling of local reinforcement of the node with fibre concrete is used. Materials for the nodes: chord and struts of the node — steel of S255 grade according to GOST 27772–2015 with design resistance 240 MPa, local filling — fibre concrete with elastic modulus not lower than 27,000 MPa and design resistance to compression Rb = 11.5 MPa.

Results. The main results of the work consist in the analytical study of truss nodes made of square hollow sections locally reinforced with fibre concrete block, the development of a method for calculating the fibre concrete block as a beam on an elastic base based on the results of numerical experiments in the software package АNSYS.

Conclusions. The significance of the obtained results for the construction industry consists in the fact that the possible approaches to the definition of different methods of calculation of fibre concrete block as a part of reinforced nodes of trusses made of square hollow sections were considered in order to reduce metal consumption and deformability. The results obtained in numerical studies of the base stiffness factor of fibre concrete block and the results obtained using the software package АNSYS showed that they are close to the results of calculating the stiffness factor of fibre concrete block in locally reinforced nodes of trusses made of square hollow sections reliably.

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