 Chernov Yu.T.
Chernov Yu.T. Chernov Yu.T.
Doctor of Technical Science, Professor. Moscow State University of Civil Engineering (MGSU) National Research University, Moscow, Russian Federation

## Publications

A calculation method for structures under seismic impacts is proposed taking into account changes in buildings' structural design during deformation, based on the normal forms
method and the presentation of design forms for calculating seismic forces in the form of expansions in the forms of natural vibrations. These formulas are close to the calculated ones given in a number of standard documents. The solution is made in time steps. At each step, the structural design is adopted from the results of the static calculation for seismic forces determined at the previous stage. The solution method is getting built in the form of forms expansions using the software MATHCAD. The seismic forces numerical values are
calculated at each time step, taking into account changes in the structural design in the previous step by static calculation for seismic forces impacts. The proposed approach allows us to evaluate the seismic forces values, taking into account changes in the structural design during oscillations at each time step. A change in the structural design is evaluated by static calculation based on seismic forces determined in the previous step. The coefficient K1 values were estimated as the ratio of seismic forces at the stage preceding
failure to seismic forces at the stage corresponding to the end of the elastic stage.

Some computational methods for nonlinear systems with a finite number of degrees of freedom are considered. These methods are mainly applied to the analysis of systems with broken-line characteristics and lock-out braces. Two computational problems are considered: the vibration isolated system with a nonlinear characteristic and the system with a lock-out brace. Solutions of these problems are obtained by the method based on solution of integral equations close to the motion equations.

A method is given for calculating vibration isolation systems with a viscous dampers as nonlinear systems with single and two degrees of freedom. Nonlinearity is determined by the inclusion  of additional dissipative forces in zones of large displacements (near resonant zones at start-up and shutdown of equipment). The method is illustrated by an example of calculating a system with single degree of freedom. The results of the calculation shows that the inclusion of viscous friction dampers in the transient modes makes it possible to significantly reduce the levels of oscillations during passage through the resonance, and the maximum displacements in the resonance zone are  practically independent of the time intervals in the starting and  stopping modes.