Introduction. On February 6, 2023, a powerful earthquake occurred in Turkey. The uniqueness of the earthquake is due to the horizontal accelerations of the free surface of the earth, which exceed the acceleration of gravity. The duration of the earthquake was almost 4 minutes.

Aim. To substantiate the possibility of reducing long-term accelerograms of earthquakes without significant loss of accuracy in assessing the seismic impact on buildings and structures. Improvement of methods for analyzing seismic resistance using energy criteria and reaction spectra of linear and nonlinear oscillators to improve the reliability of the design of buildings and structures in seismic areas.

Materials and methods. Given the significant length of the accelerograms, they were
pre-truncated to optimize numerical calculations. Energy criteria, such as Arias, specific energy density, and absolute cumulative velocity, were used to compare the full and truncated records. Spectral analysis was performed using models of linear and nonlinear oscillators. The intensity was also assessed using the MSK-64 scale, and the seismic load was analyzed.

Results. It was found that truncation of accelerograms leads to minor deviations in the quantitative characteristics of energy criteria, and the response spectra of linear oscillators for the full and truncated records are almost identical. The spectra of nonlinear oscillators were also constructed.

Conclusions. Energy criteria are suitable for truncating accelerogram records. The reaction spectra of inelastic oscillators allow for the refinement of parameters for spectral analysis in accordance with current standards. The most reliable criterion for failure is the maximum energy of plastic deformation in a half-cycle.

In the deterministic analysis of building structures, instrumental or synthesized accelerograms are used as initial data. As a rule, earthquake records corresponding to low-intensity accelerograms are available at each site. Very often instrumental recordings of high-intensity earthquakes are missing. To correct this situation, an algorithm has been developed for modeling low-intensity accelerograms to high-intensity accelerograms using a wavelet transform.

 For deterministic analysis of building structures it is necessary to set real or synthesized accelerograms as input data. This analysis requires considerable time, as it is performed by a step-bystep method. Real accelerograms can be of considerable length and
require a lot of calculations. As a rule, accelerograms have maximum values of amplitudes on a small temporal site. The article considers the possibility of using only a part of the accelerogram without loss of adequacy of calculation of seismic reactions of inelastic systems. The method of truncation of extended earthquake accelerograms for the analysis of nonlinear systems is defined. The necessity of application of the energy criterion is shown. Nonlinear oscillators for different materials are considered.

The analysis of accelerograms recorded both on the free surface and on the bridge structures during a strong earthquake was carried out. 17 records of the earthquake that occurred on January 1, 2023 in the Rio Dell area – Highway 101 / Bridge over the Ili River (USA) are considered. Energy criteria are calculated for each accelerogram: Arias, absolute  cumulative velocity and specific energy density.

A comparison of these criteria has been performed. The conclusion is made about the low efficiency of energy criteria for the analysis of seismic resistance of structures. The fluctuations of the bridge's branded span structure into vertical and horizontal vibrations are considered in more detail. Based on the analysis of the calculated displacements, a conclusion is made about the effectiveness of seismic isolation of the pillars of the corporate span.

In the deterministic analysis of building structures, real accelerograms are used as input data. Very often, only instrumental recordings of accelerograms that are not cleared of noise are publicly available. Such accelerograms cannot be used directly in the analysis of building structures. Various broadband filters are used to adjust the instrumental recordings of accelerographs. This article discusses the possibility of applying filters based on the wavelet transform.

The technique of the algorithm of filtering from the noise of the source data is considered. As an efficiency of this filtering algorithm, a comparative analysis of the dynamic coefficient and the energy criteria of the pulse and Arias for the corrected and instrumental accelerograms is carried out.