Exchange rate by seismic resistance

Introduction

Our republic is located in a zone of high seismic activity, where destructive earthquakes with a force of 7 to 9 or more points are possible. The design and construction of earthquake-resistant buildings is of great social importance, as it preserves people's lives and material values ​ ​ in possible earthquakes.

Design philosophy for earthquake-resistant buildings:

1) Buildings and structures operated in seismic areas experience additional dynamic alternating effects during earthquakes. Their bearing capacity shall be ensured with simultaneous action of operational and seismic loads.

2) Earthquake resistance of buildings and structures is provided by :

a) Selection of a seismic-friendly construction area and rational space-planning solution of the building;

3) When choosing a construction site, it should be borne in mind that with an increase in the balance of the construction site, the costs of performing antiseismic measures also increase. Therefore, for the construction of buildings and structures, the construction site must be chosen with a lower earthquake intensity.

4) Seismicity of the construction site is determined by maps of seismic zoning of the territory or by the list of settlements. Refinement of design seismicity shall be carried out taking into account the category of soils by seismic properties or by maps of microseismoration. For Bishkek and large cities, as well as during the construction of especially important buildings and structures, microzoning is carried out on the basis of instrumental studies.

5) The shape of buildings, as well as the distribution in plan of centers of stiffness and mass, have a large effect on the value of seismic load and its distribution between vertical structural elements. Therefore, the space-planning and structural solutions of the building must meet the conditions of symmetry and uniform distribution of masses and tokens.

6) In case of complex planning solution of the building and presence of height difference of one part relative to the other, the building is cut by vertical antiseismic seams into separate compartments of simple shape. The height of the building within the compartment is assigned the same.

7) Elements of the main load-bearing structures (columns, girders, bearing walls, connections, stiffening diaphragms) are recommended to perform regular structure and to arrange them evenly and symmetrically within the compartments to ensure uniform distribution of stiffness in the plan.

8) The main bearing structures shall be monolithic and uniform. In prefabricated structures, the dimensions of the elements should be enlarged. Special attention should be paid to butt joints. They should be simple, reliable and, if possible, located outside the zones of maximum forces.

9) During design, measures should be provided that allow the development of plastic deformations in the nodes that increase their resistance to seismic impacts.

10) When designing buildings and structures in seismic areas, it is necessary to use new progressive materials and structures that reduce the total weight of the building. Reduction of seismic load can be achieved both by application of light materials and by arrangement of heavy equipment on the lower floor.

11) For rational and full use of the bearing capacity of all vertical structures of the building, its floors must be rigid in their plane. For this purpose, antiseismic belts for the entire width of the wall are made along the entire perimeter of the compartment and levels of interstage floors. In prefabricated floors, the seams between the panels are frozen with fine-grained concrete or cement mortar with the arrangement of keys and welding of longitudinal reinforcement outlets from the panels.

12) Antiseismic seams shall cut buildings into compartments along the entire height of the building. It is allowed not to arrange a seam in the foundation, except when it coincides with the sedimentary one.

13) The width of the antiseismic seam is determined by calculation or assigned depending on the height of the structure. According to the design requirement, at a building height of up to 6 meters, the width of the seam is taken to be at least 3 cm and increases by 3 cm for every 6 meters of height.

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