Numerical research of the coefficients of the dynamic work of steel framing covers reduced to a beam structure under the action of a concentrated impulsive load

Abstract

The study of the operation of the steel truss of the covering of buildings during the action of a concentrated impulsive load. A generalized methodological approach to assessing the dynamic properties of steel roof trusses under the action of a concentrated impulsive load is given. The work of the steel structure is considered as the work of a single-span hinged Euler-Bernoulli beam taking into account the coefficient of shear deformation of the section. Analytical solutions of deflections and bending moments are traditionally presented in the form of the sum of series of trigometric functions by the forms of oscillations. The evaluation of the dynamic performance of the beam-type elastic structure was performed through numerical studies of the values of the structure's dynamism coefficients for deflections and the dynamism coefficient for the bending moment. It has been confirmed that the work of beam structures during the action of an impulsive concentrated load is divided into two phases, the first phase of the construction is described by analytical dependences during the action of the impulse. The second phase of the structure's operation is described by analytical dependences for the time when the action of the he study of the operation of the steel truss of the covering of buildings during the action of a concentrated impulsive load. A generalized methodological approach to assessing the dynamic properties of steel roof trusses under the action of a concentrated impulsive load is given. The work of the steel structure is considered as the work of a single-span hinged Euler-Bernoulli beam taking into account the coefficient of shear deformation of the section. Analytical solutions of deflections and bending moments are traditionally presented in the form of the sum of series of trigometric functions by the forms of oscillations. The evaluation of the dynamic performance of the beam-type elastic structure was performed through numerical studies of the values of the structure's dynamism coefficients for deflections and the dynamism coefficient for the bending moment. It has been confirmed that the work of beam structures during the action of an impulsive concentrated load is divided into two phases, the first phase of the construction is deimpulsive load occurred, but the structure continues to move, and the spans and the calculated bending moment acquire maximum values. Numerical studies of the accuracy of the values of the dynamism coefficients for deflections and bending moments of the steel structure of the coating by the number of members of the series were carried out. The accuracy of the solution is shown. Thus, for initial calculations, it is enough to keep members of the series from the first to the seventh. The analysis of numerical studies showed that reducing the pulse action time can significantly reduce the value of the dynamism coefficient in terms of deflection and bending moment. Increasing the duration of the impulse to half the period of natural oscillations brings the dynamic coefficient (dynamic coefficient of the impulse) closer to the value of the impact load. For initial studies, at certain values of the duration of the impulse, formulas were obtained for determining the coefficients of dynamism according to the first form of oscillations.