RU-2861414-C1 - METHOD FOR INCREASING LOAD-BEARING CAPACITY OF DEFORMED IN REGION OF PLASTIC DEFORMATIONS OF THROUGH PURLINS AND TRUSSES

Abstract

FIELD: construction. SUBSTANCE: invention is implemented by adjusting the forces in through purlins or trusses by relieving their elements without disassembling the overlying covering elements, sheathing, insulation and roofing. In the method for increasing the load-bearing capacity, residual stresses in the elements of through purlins or trusses are used, which are provided by removing live and temporary loads from the purlins or trusses, the unloading of the elements of purlins and trusses is carried out by installing on them unloading flange assemblies that duplicate the loads acting in them, in which the flanges are connected by studs with nuts, between the flanges of the flange assemblies in these elements by cutting them, tensile forces are transferred to the flange connection, forming a gap equal to the calculated deformation from the difference between the minimum and maximum operational loads, unloading to the calculated new minimum load, then the elements are reloaded using the studs and nuts of the flange assembly to the acting or new load values, taking into account 20-30% use of residual positive stresses in the linear region of the material of the elements. EFFECT: preservation of loaded, partially deformed, in the zone of plastic deformations of metal structures without their disassembly and the overlying roof structures and the use of residual stresses after loading and unloading as an additional reserve of stresses during subsequent operation under repeated loading in the same direction. 2 cl, 4 dwg

Inventors

• Shmelev Gennadii Nikolaevich
• Eremeev Pavel Valerevich
• Eremeev Valerii Pavlovich
• Novoselova Valeriia Iurevna

Dates

Publication Date

20260505

Application Date

20241228

Claims (2)

1. 1. A method for increasing the load-bearing capacity of through purlins or trusses deformed in the area of plastic deformations by regulating the forces in them due to the unloading of their elements without dismantling the overlying elements of the roof, decking, insulation and roofing, characterized in that in order to increase the load-bearing capacity, residual stresses in the elements of through purlins or trusses are used, which are provided by removing useful and temporary loads from the purlins or trusses, the unloading of the elements of purlins and trusses is carried out by installing on them unloading flange assemblies that duplicate the loads acting in them, in which the flanges are connected by studs with nuts, between the flanges of the flange assemblies in these elements, by cutting them, tensile forces are transferred to the flange connection, forming a gap equal to the calculated deformation from the difference between the minimum and maximum operating loads, unloaded to the calculated new minimum load, then the elements are additionally loaded using studs and nuts of the flange assembly to the current or new load values, taking into account 20÷30% utilization of residual positive stresses in the linear operating range of the element material.
2. 2. The method according to paragraph 1, characterized in that the forces in the elements of the purlins or trusses, after calculation taking into account an additional 20÷30% of the residual stresses, are redistributed again, correcting them by adjusting the gaps in the cut elements, and the correction of the forces in the racks is carried out by driving in wedges.

Description

The invention relates to the field of construction and can be used to increase the load-bearing capacity of through purlins and trusses that have undergone significant plastic deformations without dismantling the overlying elements of the insulation and roof covering. There are known solutions for strengthening metal structures with the construction of additional elements that relieve the required structures before reinforcement (Steel structures, structures made of aluminum alloys. Designer's Handbook edited by V. V. Kuznetsov M: ASV pp. 354-374) A solution is also known using a truss system (US 342 7773 A, 18.02.1969, fat. 1-10), which relieves the deformed beam by means of an additional truss device. A device for maintaining pre-tensioning force is known according to patent No. 985220 from 03.01.82, which is used to increase the load-bearing capacity of a building structure and prevent dynamic impact. The prototype of the invention is a method for strengthening building frame trusses (SU 1300132 A1) E 04G 23/00, E 04C 3/08), in which truss elements are reinforced by installing posts next to the columns, to which truss unloading elements and a truss rod are attached. This method has a significant drawback in terms of the installation of additional posts and a truss tightening system that unloads the truss elements (the diagonals). The technical result of the invention is the preservation of loaded, partially deformed, metal structures in the zone of plastic deformations without disassembling them and the overlying covering structures and the use of residual stresses after loading and unloading as an additional stress reserve of 20÷30% in further work upon repeated loading in the same direction, with the sign (“+”, “-”) of the main stresses being preserved. 1. Maximum residual stresses are achieved by removing useful and temporary loads (snow, wind, crane), as well as by a device duplicating the main forces - a flange unit installed on loaded rods with the possibility of unloading them to the minimum design value only from permanent loads. Due to the duplicating device, a force is created in the flange studs equal in magnitude and sign ("+", "-") in the active main element. Then, in the main element, we relieve the force by cutting the main element between the flanges, transferring the force to the flange connection (studs). Controlled gap " "In the cut element, residual stress is formed during further loading of the main element by the flange assembly using studs and nuts to the minimum design force Ppl , at which the calculated plastic deformations occur. The main element is relieved from Ppl to Ppos using studs and nuts of the flange assembly. Thus, residual stresses of approximately 20-30% of the fundamental stresses have formed in the main element, which can be utilized under full loading with temporary and useful loads already within the linear operating range of the element material. The forces in the structural elements can be redistributed, taking into account the resulting reserve from residual stresses in the elements, by adjusting the gaps in the flange assemblies and using wedges. Figure 1 shows a diagram of the reinforcement of a deformed through purlin in the form of a beam 1 with a truss tie 3, a rack 2 and a flange assembly 4; Figure 2 shows a diagram of a through two-span truss beam with a deformed upper chord 5, a tie 6 with a flange unit 4 and reinforcing elements 7 and 8; Figure 3 shows the stress diagrams: a) residual stresses from rolling, bending, welding (parasitic) σ pr simple ; b) plastic deformations from preliminary loading σ пл ; c) residual stresses in loaded zones of plastic deformation of elements [σ ост ] (useful); d) stress from new loading after reinforcement σ нов; d) total stresses σ upr sum after unloading and reloading in zones subjected to plastic deformations (σ upr sum = σ pl + σ ost ) . Figure 4 shows: a) flange units on deformed elements 2,3,5,6 to relieve the load to the calculated value P pos with the formation of a gap " » by cutting elements 1,3,5,6 and then adjusting the force with studs 12 and nuts 11; b) a unit for regulating the force in post 2 by driving wedges 9 between beam 1 and post 2; c) a connection point for diagonals 13 and 14 to the upper chord 5 to redistribute forces in the truss using wedges 9. The method of using residual stresses and regulating forces in deformed through beams and trusses is implemented in the following sequence: 1. Loaded deformed elements 1,3,5,6 of structures, including those in the area of plastic deformations, are not disassembled, and the overlying layers are also not: the flooring, insulation and roofing remain in working condition (Fig. 1, 2), and the load-bearing elements only under a constant load P pos. 2. On the deformed elements 1,3,5,6, duplicate (tension, compression and bending) forces are installed in them by devices 4 flange units 4 (Fig. 1,2.) 3. By cutting elements 1,3,5,6 between flanges 4, the calcula