Qualifying Scientific Paper as a Manuscript.
Thesis for a PhD Degree in Engineering, Major 05.23.01 «Building Designs, Buildings and Structures» (19 - Architecture and Civil Engineering). – Prydniprovska State Academy of Civil Engineering and Architecture of the Ministry of Education and Science of Ukraine, Dnipro, 2021.
The Thesis is devoted to solving the actual scientific and practical problem of ensuring earthquake resistance of multi-storey buildings depending on design layouts and changes in earthquake activity of the construction site.
The Thesis Paper provides a brief overview of research to ensure reliability and design safety of buildings being engineered in earthquake areas. The general design requirements of ensuring earthquake resistance of buildings were considered, and the ways to increase earthquake resistance of buildings, and methods to proportionate buildings for seismic impacts were analyzed.
The analysis of modern regulatory documents of different countries, results of theoretical research and cited literature showed that the work to improve methods of the building design calculation for seismic loads and to increase earthquake resistance of buildings is currently performed in active mode.
Earthquake-resistant engineering of buildings is based on force calculation and earthquake accounting by static equivalent forces, which are calculated using the elastic reaction spectra (linear-spectral method) that link the law of soil motion to the absolute acceleration of the model in the form of a nonlinear oscillator.
Design calculation with due account for the plastic and nonlinear behavior and even with an eye towards destruction of individual design elements of the building requires the use of more complex mechanical and mathematical models and theories. It is necessary to take into account the redistribution of forces along the design associated with the appearance of zones of plastic deformation in it. However, in all cases, the criterion for assessing the load-bearing capacity of the design is the principle of comparing external and internal forces.
Therefore, the scientific interest in solving problems to ensure earthquake resistance of multi-storey buildings are the tasks for choosing a rational and effective way to increase their earthquake resistance during the reconstruction and dependence of the cost of seismic protection measures in existing buildings on changes in earthquake activity of the construction site; for studying influence of irregularity of the building design layout on earthquake resistance.
The technique and algorithm of numerical modeling of buildings with the irregular design layout at seismic impact calculations were developed on the basis of the method of the static nonlinear calculation realized in the ETABS software package (Nonlinear v8.08). The technique is based on the determination of nonlinear displacements of the building with the use of the bearing capacity spectrum of the building. Numerical modeling and analysis of the seismic behavior of five options of models of the building with the irregular design layout were performed.
Analysis of the bearing capacity spectra of models of the building with the irregular design layout showed that buildings with the irregular design layout in the plan have a lower ability to withstand transverse loads compared to the regular design layout. It was also found that frame buildings with the irregular design layout under seismic impacts could operate in the elastic stage; this depends on the location of irregularity in the building plan, as well as the plastic properties of design materials of the building.
In the paper, there have been given the results of influence of the reconstruction on the stress-strain state of the facility and search for the most rational and effective way to increase earthquake resistance of the building in progress and develop methods for the comparative analysis of different options for increasing earthquake resistance of the building, as well as estimation of its practical use.
Since the introduction of the new design standards Civil Engineering in Earthquake Areas of Ukraine, earthquake endangered areas with a general increase in their calculated earthquake activity have been significantly expanded, and the 6-point territories have been included in the list of earthquake zones.
The Thesis Paper solves an important scientific and practical problem, which is to study the seismic behavior of multi-storey buildings while increasing earthquake resistance of existing buildings, to change earthquake activity of the construction site and irregular design layout, and to develop scientifically sound provisions and methods for their calculation.
Key words: seismic impact, stress-strain state, earthquake resistance, bearing capacity spectrum, buildings, reconstruction.
