Buildings and the constructions erected in seismodangerous (subject to earthquakes) areas, should possess ability resist to seismic influences without loss of operational qualities, i.e. To be aseismic.
Seismic stability of buildings and constructions is provided with application of constructive decisions, designs and the materials corresponding to seismicity (intensity of seismic influence in points) sites, and also strict observance of rules and requirements on erection of designs and manufacture of works in seismic countries.
Number of constructive antiseismic actions concerns: application of aseismic constructive systems. Division of buildings and constructions in the plan for parts antiseismic seams, restriction of height of buildings, a regulation of conditions and a scope of materials by their kinds; application in constructive schemes of antiseismic belts; reinforcing of elements of stone designs and a number of other measures provided by norms of designing and building.
The Specified actions are concretised by calculations and reflected in projects. So, for example, in buildings with walls from a brick or a stone laying in level of overlappings and coverings it is necessary to arrange antiseismic belts on all longitudinal and cross-section walls, carried out of monolithic ferro-concrete, or national teams with zamonolichivaniem joints and continuous reinforcing. Thus belts of the top floor should be connected with a laying vertical releases of armature. Constructive decisions of belts, their reinforcing are specified in projects.
In interfaces of walls in a laying stack armaturnye grids in length 1,5м with section of longitudinal armature in a grid not less than 1 sm 2 . Grids stack through 700мм on laying height at seismicity - 7... 8 points and through 500мм - at 9 points. A laying of self-bearing walls fasten to skeleton designs the flexible communications which are not interfering horizontal displacement of a skeleton.
Between walls and skeleton columns backlashes in size not less 20мм are provided. On all length of walls level of top of window apertures, in covering level arrange the antiseismic belts connected to a skeleton. Opiranie panels of overlappings on a laying of walls should be not less than for the length 120мм, and on the vibrated brick panels and blocks - not less 90мм. Beams, runs and plates of overlappings, beams of wooden overlappings zaankerivajut in antiseismic belts (concrete decisions are given in projects). Ordinary crosspieces in seismodangerous areas do not apply. Ferro-concrete crosspieces arrange, as a rule, for all width of walls and close up in a laying on depth not less 350мм, at width of an aperture 1,5м - zadelka crosspieces it is supposed on 250мм.
Seismic stability of stone buildings provide also with many other constructive methods, for example, a fastening of ladder marches and platforms with overlappings, the device of ferro-concrete frames in window and doorways of staircases etc. All design decisions on antiseismic measures should be carried out strictly at building of buildings.
At use of materials by norms also provide a number of measures. For example, in seismic countries in cities and settlements building construction with walls from syrtsovogo (not burnt) brick, samana and gruntoblokov is forbidden. In rural settlements from these materials building only in areas with seismicity to 8 points, and only one-storeyed buildings, under condition of strengthening of walls wooden anti-septirovannym a skeleton with diagonal communications is supposed. For a laying of walls, or skeleton fillings in seismodangerous zones the brick corpulent or hollow (with apertures in the size to 15мм) is authorised to apply marks not more low 75. It is authorised to apply concrete stones, continuous and hollow blocks from easy concrete, mark not more low 50; stones or blocks from shell rocks and limestones, marks not less than 35 and from tufov (except felzitovogo) marks not more low 50.
The Laying of walls carry out on the mixed cement mortals of mark not more low 25 in summer conditions and not more low 50 - in winter, with the special additives raising coupling of a solution with a brick or a stone. At settlement seismicity of 7 points application of ceramic stones of mark not more low 75, and also erection of walls of buildings from a laying on solutions with softeners without application of the special additives raising durability of coupling of a solution with a brick or a stone is supposed.
The Major requirement shown to a stone laying in seismic countries, durability on coupling with a solution is. On resistibility to seismic influences that is defined by time resistance to an axial stretching on not tied up seams (effort of a separation of the brick laid on a solution, from a laying), the layings applied in seismodangerous zones, share on two categories.
The Laying of the first category at which value of normal coupling between a stone (brick) and a solution should be not less than 180 kpa (1,8 kg/sm 2 ). The laying of the second category should have durability of coupling not less than 120 kpa (1,2 kg/sm 2 ). The laying with durability of coupling of a solution with a brick (stone) is less 120 kpa century seismodangerous areas it is not supposed. On occasion at seismicity of 7 points, at application in the project of special actions, it can be supposed (under the decision of the design organisation) decrease in durability of coupling in a laying to bokpa (0,6 kg/sm 2 ).
At erection of stone designs in seismic countries it is necessary to fulfil strictly special requirements of manufacture of the works, layings providing seismostability. A laying spend for all thickness of a design in everyone to a number. It carry out with application of the single-row (chain) bandaging, all seams of a laying (horizontal, vertical, cross-section and longitudinal) fill with a solution completely with podrezkoj a solution on laying lateral aspects. Time ruptures in an erected laying should be ended only inclined shtraboj and to have out of places of constructive reinforcing of walls. Brick surfaces (stones, blocks) before packing are necessary for clearing of a dust and a dirt: for a laying on usual solutions in areas with a hot climate - a water stream, for a laying on polimertsementnyh solutions - brushes or compressed air.
It is necessary to supervise strictly durability of coupling of a solution with a brick (stone). In a laying of 7-day age the coupling size should make approximately 50% of durability of 28-day age of a laying of a corresponding class. At smaller durability it is necessary to stop manufacture of works to the decision of a question the design organisation. Prior to the beginning of stone works the building laboratory defines an optimum parity between preliminary humidifying local stenovogo a stone material and the water maintenance rastvornoj mixes. Solutions apply with high water-retaining ability (branch of water no more than 2%). Application of cement mortals without softeners is not supposed. At a laying in the locations of antiseismic seams dividing a building it is necessary to watch, that they were not filled with a solution, dust. It is forbidden to reduce design width of seams.
It is necessary to carry out accurately the actions provided by the project of manufacture of works on care by the hardening laying (on humidifying and protection from fast drying, etc.). It is necessary to consider features of a climate and to provide reception of demanded durability of a laying, including at erection of designs at negative temperatures of external air with application protivomoroznyh additives.
Performance of a brick and stone laying at negative temperature at settlement seismicity of 9 points and more is forbidden.