RU1795337C - Method of testing carrying capacity of construction structure - Google Patents

Abstract

Usage: construction, testing of structures of operating structures to assess their bearing capacity. SUMMARY OF THE INVENTION: a real construction is examined. They load it with a stepped compensation load directed oppositely acting and not exceeding it in magnitude. 1 ill. .

Description

The method relates to the field of construction and can be used in testing designs of operational weapons to assess the bearing capacity

A known method of controlling building structures by identifying the ultimate tjibix load-bearing capacities when bringing Structures to destruction.

The disadvantage of this method is that it is not applicable to real objects, i.K. their destruction in order to identify ultimate load-bearing capabilities is not economically justified.

The closest known to the pre- / (agile) is a method for testing structural constructions, including the examination of real structures, the infringement of their step load and the measurement of deformations.

: The disadvantage of this method is labor-intensive, namely, the need to allocate special periods of time for technological windows that are in operation. The buildings under construction are associated with a production stop. The latter circumstance has to be taken into account for any of the currently used methods of e-loading (testing methods) of the structures of operating buildings and structures. The purpose of the invention is to increase labor productivity during testing by conducting tests without stopping the process and dismantling the equipment.

The goal is achieved in that in a method for testing the bearing capacity of building structures, including examination of real structures, loading them with a step load and measuring strain. the actual design is loaded with a compensating step load directed oppositely acting and not stopping in magnitude.

The method is carried out as follows.

Prior to testing, by examining the structures, the actual parameters of the geometry of the structural elements, loads and physical and mechanical characteristics of the materials are established. According to the established characteristics, the calculation limits the values of operational

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loads for the structure in question. Then, an oppositely useful trial compensation load is applied in steps to the structure. During the application of the steps by a plug, the load is fixed by the deformation of the structure.

Based on the results of the analysis of the experimental dependences, the load-strain specifies the mechanical characteristics of the material of the structure and the boundary conditions that determine its relationship with other elements of the structure. Taking into account the specified characteristics and real boundary conditions, the operational load of the considered structural element is calculated and compared with the expected one.

The drawing shows a graph corresponding to the test of the beam with a static load, where 1 is the payload loading branch PI, 2 is the compensation branch (from Pa load), 3 is the load removal branch P2. 4 - branch of removing payload 2 Pi, 1-4 - linear graphical interpolation of the load-strain dependence in the traditional test scheme, 2-3 - linear graphical interpolation of the load-strain dependence according to the proposed method.

Example, Test a reinforced concrete beam on two pillars. And a beam is installed with instruments of gauge type indicators (Messur) and two construction tensometers, N. A. Aistova. Indicators on the supports fix the deformations in order to exclude the influence of random turns and compression of the supports on the amount of deflection. Deflectors installed in the middle of the span measure deflections / Strain gauges record the deformations of the concrete of the compressed zone and reinforcement in the stretched zone, respectively.

The test cycle consists of the following steps: they simulate the payload using a linkage system. The beam is loaded on top of the steps of the load RF with

simultaneous fixation of deformations by dial gauges and tensometers (branch 1, Fig. 1).

The compensating load Pz is applied in a stepwise and oppositely directed payload using a DG-25 jack. with simultaneous fixation of deformations. The magnitude of the compensation load is equal to the useful (branch 2) ..

Removing the compensating load P2 (unloading jacks) in steps, with simultaneous fixation of deformations (branch

h). :.

, Removing the payload Pi (unloading the linkage system) in steps, with simultaneous fixation of deformations (branch 4).

B load-unload cycles are performed. The results of the graphic processing of the test results in one of the cycles are shown in Fig. 1 in the form of a load-strain relationship. Characteristic for the proposed test method are dependencies 2 and 3 (compensation

the branch and the branch to remove the compensation on. loads). The load-strain dependences correspond to the slope of a straight line 2-3 (compensation load), the interpolating branches 2 and 3 in Fig. 1. In traditional test methods, the characteristic of the structural material is determined by the slope of the straight line 1-4 (branches of the payload or cases of its preliminary removal - branches of a similar test load).

A comparison of the slope of lines 2-3 and 1-4 indicates a satisfactory accuracy in predicting the strength parameters

(deformable ™) design according to the proposed method. The discrepancy in the deflection of the beam at the same load according to the traditional and proposed methods is within 20%. Similar results were obtained in all test cycles of the beam on 2 supports.

Formulas of the invention

A method of testing the bearing capacity of building structures, including examination of real structures, loading them with a step load and measuring deformations, characterized in that, in order to increase labor productivity during tests by conducting tests without stopping the process and dismantling the equipment, the real structure is loaded with compensating step load directed opposite, acting and not exceeding it in magnitude.