METHOD FOR NON-DESTRUCTIVE DETERMINATION AND MONITORING OF THE BEARING CAPACITY OF STEEL TRUSSES Russian patent published in 2022 - IPC G01M5/00 G01N3/12 

FIELD: non-destructive testing.

SUBSTANCE: invention relates to non-destructive testing of steel trusses by static load and can be used in the inspection and testing of buildings and structures. Tests are carried out in the absence of snow load. Each truss rod is assigned a number j=1, 2, ..., k, a linear displacement meter is installed in the middle of the truss span, and a deformation meter is installed on each rod of the truss under study in the middle of its length. At the nodes of the farm, where the snow load is transmitted through the runs, a test concentrated load is applied in five successive steps - 10% (F₁), 20% (F₂), 30% (F₃), 40% (F₄) and 50% (F₅) of maximum allowable load on the truss , calculated theoretically, and each step of the test load is maintained until the values of relative deformations and linear displacements (deflections) stabilize, the value of deflection f_i, i=1.2, .., 5, and the relative deformation for each element ɛ_i are fixed, i=1, 2, ... 5, at a given test load stage F_i, the next test load stage F_i+1 is applied, and after the fifth load stage is maintained, the test load is removed and the tests are repeated after stabilization of the relative deformations of the rods and the deflection of the truss. The identified functions of the dependence of the relative deformation on the load are substituted with the limiting values of the relative deformation calculated for each rod separately (for compressed rods - according to the stability criterion and according to the proportionality limit criterion; for tensioned rods - according to the proportionality limit criterion). As a result of testing the truss, its bearing capacity is revealed in the form of an interval of ultimate load [; ], as well as the maximum allowable deflection in the form of an interval [; ]. The linear displacement meter is left in the specified place, after which, during the further operation of the farm, readings are taken from the linear displacement meter at certain intervals and compared with the limit values.

EFFECT: increasing the accuracy and reliability of determining the bearing capacity of steel trusses at the stage of their operation, as well as the possibility of controlling and monitoring the bearing capacity of the truss.

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