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THE BASIC PROVISIONS ON THE DIAGNOSIS OF TECHNICAL CONDITION OF THE BUILDING STRUCTURES AND GROUNDS OF BUILDINGS AND STRUCTURES

Diagnosis of technical condition of buildings and structures is carried out through a combination of vzaimosoglasujushhih and complementary research, computational and analytical procedures and the completeness of the list which in each case clarifies specialized organization survey.
In designing the programme of Visual and instrumental examinations set this amount and order of research procedures, which with minimal research work (especially instrumental examinations and laboratory assays), you can get full information about faults, defects and damage structures.
Visual inspection should be guided by the rule that the most probable sites of damage structures in industrial buildings and structures include:
-mainly in the areas of warehousing heavy loads; a very loaded columns, walls, foundations, footings; in the ground wet soils; in the field of possible vibration or shock loads;
-for foundations-in areas wetted soil especially aggressive liquids; in the areas of vibration, shock, privantazhen’; in the construction of heavy expansion; at the device of neighbouring pits; When informal vodootlive and vodoponizhenii;
-columns-in the most intense areas of interface with bedrock at consoles in joints of precast columns in height near the floor where possible ingress of corrosive liquid or mechanical damage to the transport, loading and unloading equipment at nodes joining with crossbars slabs and coatings;
-for beams and plates of overlappings-in the area of maximum bending moments, shear forces, action-focused efforts, transmission of vibration and shock loads, aggressive liquids, gases, dust, in places of joining;
-coatings-in places of high moisture and damage from the premises and technology of dust accumulations at sites with high density or saturated with moisture insulation;

 -for walls-in places of high hydration with freezing and thawing, in joints of prefabricated walls, primykanijah to the floor and overlappings.

The most typical defects and damage to the structures to be detected by Visual inspection, include:

 -defects associated with disabilities project (mismatch design scheme valid conditions, deviations from norms of design);
 -defects in manufacturing structures, which admitted to manufacturing plants;
 -defects of the installation of structures and construction of buildings (constructions);
-mechanical damages from breach of exploitation;
-damage from unforeseen project static, dynamic, thermal effects;
-damage from external aggressions and work environment Wednesday.
For complete diagnosis of technical condition of buildings and constructions appropriate surveys and experiments in parallel with laboratory determinations also plan and carry out diagnostic procedures:-analysis and identify changes in the basic design and calculation assumptions (for buildings and constructions in General and their individual parts and structures) that have arisen during the period of operation;
-analysis of defects and damages, changes the characteristics of the materials, soils and grounds;
-adjustment of the calculation models of elements of structures, due to the presence of defects and damages, changes in material characteristics and soil;
-verifying calculations elements, structures, foundations for the adjusted payment models and taking into account developments arising in the design and calculation assumptions during the operation;
-assessment of technical condition elements, structures, foundations, in accordance with the criteria;
-assessment of technical condition of buildings and structures in General, depending on the technical condition of its elements, structures, foundations.
Analysis and identification of changes to the basic design and calculation assumptions that have arisen during the period of operation, should be carried out by comparing such project (normalized) and actual (at the time of the survey and certification) indicators and their parameters:
-functional purpose buildings and structures;
-the level of responsibility of buildings and structures of economic, social and environmental consequences of their refusal (GOST 27751-88) or class kapital’nosti according to the norms of design of hydraulic structures and related to levels of responsibility and reliability coefficients Yn kapital’nosti classes;
 -normative and calculated values of loads and impacts (including: own weight, atmospheric, gidrosfernye, technology, seismological loads, etc.);
 -features and parameters calculation;
-aggressive natural and productive Wednesday;
 -Engineering-geological and hydrogeological conditions.
Normative values of loads you need to determine:
-for loads from its own weight-for measurements of geometrical sizes of designs, check the definitions of medium density materials (this definition error shall not exceed ± 5%);
-for atmospheric and hydrospheric loads and effects-according to the hydrometeorological service stations closest to the object with the given instructions 2.01.14-83 and Snip 1.02.07-87;
-for static and dynamic loads on the passport data of the equipment is operated;

 -for seismic impacts and on undermined territories-in accordance with the requirements of normative instruments in force at the time of the surveys.
When testing the calculation should take into account those estimated situations that may actually occur in the residual service life of structures. With each settlement situation must be qualified:
-payment schemes and designs;
-types of loads;
-the values of the coefficients of the working conditions, the coefficients of combinations of loads and safety factors;
-list of limit States that must be seen in the settlement of the situation.
Degree natural aggressiveness and production should be determined Wednesday: for groundwater-to-87 1.02.07 and Snip 2.03.11-85-85;  for air Wednesday-according to snip 2.03.11-85-85.
Changes to the geotechnical and hydrogeological conditions of the grounds of the building (construction) should be determined in accordance with the requirements of 1.02.07-87.
Analysis of defects and damages and their influence on the bearing capacity and durability of structures and grounds, it is recommended to carry out tailored to different types of designs. It is recommended to use the following groups of defects and damages:
1. Defects: rationing, design, construction and testing.
2. Damage: mechanical destruction, mechanical wear, corrosive wear (atmospheric corrosion, chemical attack), deformation and displacement (deflections, angular deformity, precipitation, banks).
Physical-mechanical characteristics of bearing and enclosing structures of buildings and structures should be defined:
-using standard non-destructive techniques (ultrasound, plastic deformation, etc.);
-by withdrawing samples of materials to perform standard laboratory tests.
The number of property definitions of the strength of materials, we recommend that you designate, subject to the condition of the structures. While the availability of normative values of strength characteristics of the material must not be less than 0.95.
When conducting quality control materials should be guided by the requirements and guidelines of current state standards.
Withdrawal of material should only be performed with the secondary and nenaprjazhennyh parts of building elements and constructions. Places in designs from which confiscated specimens must be securely fix and when needs strengthened.
Deviation of spatial position of bearing and protecting designs and their estimated sizes should identify the methods set out in Snip 3.01.03-84. Status of key nodes and connections determine by measurements of Visual inspections or expert assessments.
Section wear of bearing and enclosing structures of buildings (structures) should be determined by direct measurement of the square cross sections of the main elements of bearing and protecting designs in the most defective or damaged, as well as the most stressful places. When the layers of materials affected by corrosion, do not count.
Check calculations of structural elements, the grounds should be performed in accordance with GOST 27751-88 and the design standards current at the time of the surveys. Use validation rules, design calculations on which to project the building (construction), but at the time of the surveys have been cancelled, is permitted only with the written consent of the Organization, which developed the new rules.
By combining analysis of defects and damages, as well as the results of test calculations defined technical condition of individual designs. On bearing capacity and performance characteristics of the design, we recommend that you refer to one of the following conditions:
-State structures I-normal. Actual effort in the elements and sections do not exceed allowable on the calculation. Defects and damage, impeding the normal operation or reduce the carrying capacity or durability;
-the State of design II-satisfactory. On bearing capacity and operating conditions correspond to and. Defects and damage have occurred, which can reduce the durability of the design. We need measures to protect designs;

 -the State of design III-not suitable for exploitation. Overloaded or design defects and damage have occurred, indicating a decrease of its carrying capacity. But on the basis of test calculations and analysis of damage possible to ensure its integrity to gain time;
 -the State of design IV-emergency. Same as design III. But on the basis of test calculations and analysis of defects and damages to guarantee the integrity of structures during the period of strengthening, especially if possible “fragile” nature of the destruction. Need to pull people from the zone of possible collapse, perform an immediate discharge, take other security measures.

Buildings and structures in General, we recommend that you refer to one of these States, depending on the condition of bearing and protecting designs:

 -the condition of buildings and constructions (I) normal. The building (construction) there are no bearing and protecting designs, relevant State structures II (satisfactory), III (not suitable for normal operation) and IV (emergency);
 -the condition of buildings and constructions (II) satisfactory. The building (construction) there are no bearing and protecting designs, relevant State structures III (not suitable for normal operation) and IV (emergency);
 -the condition of buildings and structures (III)-not suitable for normal use. The building (construction) there are no bearing and protecting designs, relevant State structures IV (emergency);
 -the condition of buildings and constructions (IV)-emergency. The building (construction) there are bearing and protecting designs, relevant State structures IV (emergency).
With appropriate rationale may conduct surveys and assessment of technical condition of individual parts of the buildings and structures that can be allocated to functional and structural characteristics.

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