Analysis of the system of coefficients used to determine the calculated seismic load in regulatory design documents

Abstract

The current stage of development of the theory of seismic stability is characterized by a general tendency to refine the statement of the calculation problem. This implies a more complete and detailed description of the seismic effect and requires the use of more rigorous calculation methods. It is necessary to study the problem of the interaction of the structure with the soil in determining the influence of the nature of the soil and the conditions for laying structures in them on the dynamic characteristics. An important direction is the further improvement of the design schemes of buildings and structures that most fully reflect their physical properties, spatial functioning, torsion, and wave processes in soils and structures.

It is relevant to develop methods for calculating buildings and structures, taking into account the elastic-plastic properties of the material, which is important for assessing the actual bearing capacity of structures under seismic effects.

In the general case, when normalizing inertial seismic loads, the following coefficients can be used:

• – coefficient of variability of maximum accelerations, determined for a given construction site, regardless of the properties of the building;
• – coefficient of responsibility, which depends only on the class of responsibility of the building;
• – coefficient of a combination of seismic and non-seismic loads;
• – constructive coefficient, taking into account the features of the system, not reflected in the design scheme;
• - coefficient of limit states;
• –  coefficient taking into account energy absorption;
• – coefficient of elongation, taking into account the difference between the average (over the area of the base) and maximum accelerations.

The above system of design coefficients, with the correct designation of the design scheme of the building, makes it possible to accurately assess its seismic resistance. However, in practice, due to the traditionally established calculation and design standards, the system of design coefficients turns out to be more confusing: some coefficients are missing in the calculation formulas, and the existing standard coefficients are changed taking into account the corresponding functions.

The article analyzes the system of coefficients used to determine the design seismic load in regulatory documents for design. It is known that the history of the development of domestic design standards in the section for determining seismic forces clearly shows some inconsistency in the application of the above coefficients, as well as the instability of their numerical values.

The performed analysis of seismic coefficients showed that the existing regulatory system of calculated coefficients is sufficiently balanced, but needs improvement, since the results of calculations do not always correspond to the data of damage to buildings during earthquakes. This must be taken into account when clarifying certain details of the calculation of engineering structures.