Methods of structural analysis for resistance to progressive collapse

Introduction. Calculation methods and current normative documents used in the calculation of buildings for resistance to progressive collapse are considered. The key methods of analysis are listed and fundamenta.rules of each of them are stated. The advantages and disadvantages of these methods are analyzed. Materials and methods. The calculations of stability to progressive collapse have been carried out for a multi-span flat frame at the failure of the middle post of the ground floor. The software complex LIRA-SAPR 2021 R1.2 was used to perform calculations. The task was solved by several methods: the static calculation, quasi-static calculation and dynamic calculation. The nonlinear functioning of construction and material was considered by step-methods with using the flow curve from SP 16.13330.2017. Quasistatic calculation was performed in two variants: pulldown and pushdown analysis. The dynamic calculation was carried out by direct integration of the equations of motion using the module “Dynamics in Time”. Two variants with different element elimination time were considered. Results. The results are analyzed and summarized in Table 2. The static calculation yields force and displacement values that are clearly underestimated as compared to other methods. Forces and displacements obtained by quasistatic analysis are greater than those obtained by dynamic analysis. The results obtained in the pulldown and pushdown analyses are close in value. Conclusions. Quasistatic calculations give higher forces and displacements than dynamic calculations. The results of pushdown analysis correlate better with the results of calculations in the dynamic formulation. In order to determine forces more accurately when using quasi-static calculation, a justification of the dynamical coefficient is necessary.