Tests of Damaged Flat Trusses

Abstract

The destruction of individual structural elements is accompanied by the development of vibrations in it and the emergence of forces and displacements which have greater values than with static loading. In design practice, static calculations in which the dynamic nature of the damaged structure is taken into account when increasing the load with the help of dynamic coefficients are widely used. The dynamic factors of damage of the structure depend on the failure time of the element, i. e. time during which the resistance of the damaged element is reduced to zero. The article presents the results of experimental studies of flat trusses in case of damage to individual truss rods. Three experiments were carried out: in the first, the work of a compressed belt was studied with a loss of flexibility, in the second and third, the redistribution of efforts in the truss when the element of the lower and upper zones was damaged, respectively. According to the data obtained, the time of failure of the damaged rod in the system (time of exclusion) and the redistribution of efforts to neighboring elements of the farm were calculated. In accordance with the calculated exclusion time, recommendations were given to reduce the dynamic coefficient used in the static calculation, depending on the options for damage to the truss.