In the terminology of accounting, buildings and structures relate to fixed assets. Like any asset, they are subject to moral and physical wear and tear. And today in the proposed article we will consider one of its types. The whole topic of moral and physical wear and tear in a separate article, we will not touch on in connection with its vastness. Let's talk only about one of its varieties - namely, physical deterioration.
Concept of wear
Physical deterioration means the loss by the building, like any material object, of the initial qualities of a technical and operational nature. This happens as a result of exposure to factors of natural climatic origin and human activity. Subjected to many years of operation, any structural element, like engineering equipment, is subjected to the complex effects of chemical and physical-mechanical factors. The result is a gradual loss of performance.
By such a loss, it is customary to understand a decrease in the structural elements of a building of indicators related to strength, stiffness, and resistance. The logical result of the loss of these properties is the aging of the building with its subsequent destruction.
In addition to the huge number of aggressive factors, the wear and aging of any residential building depends on the complex of local conditions available, as well as on how well the maintenance and operation requirements are observed. Among other things, the speed of this process is affected by the quality of repairs and maintenance of the entire building in whole and in elements.
About wear stages
The physical deterioration of residential buildings is theoretically divided into two stages - disposable and unremovable. The first is characterized by a deterioration in performance indicators of a technical and economic nature. At this stage, their decrease is caused by an increasing number of failures in the functioning of elements of engineering systems and structures. The result is a shorter service life with increased maintenance and repair costs.
The main characteristic feature of irreparable wear is the impossibility of further operation of the building in accordance with the conditions for ensuring safety requirements.
You should be aware that there are methods for assessing physical wear and tear, according to which non-linear calculation of the parameters of its unremovable variety is possible. The degree of non-linearity most often depends on the quality of operation. Speaking of the latter factor, they share the force of various loads, leading to a volumetric stress state, and the aggressive influence of the external environment.
What is an aggressive environment
Under the concept of aggressive environment, the impact of which may change the properties and structure of materials. The result is a constant decrease in strength and failure of the structure. It is referred to as corrosion. Those substances and phenomena that cause corrosion and destruction or contribute to their occurrence are called acting factors (stimulants). On the contrary, those under the influence of which the process of corrosion and destruction can be slowed down belong to passivators or corrosion inhibitors.
The same conditions cannot be considered unambiguously aggressive or passive. Their nature is not universal, and each of them under certain conditions can act as a useful factor, and vice versa.
For example, the presence of warm humid air is a strong aggressive factor in relation to steel. At the same time, it serves as a positive circumstance for concrete, increasing the strength of the latter.
What is an aggressive environment
The nature of the destruction of building materials can be very diverse - chemical, physical, electrochemical, physico-chemical. There is a special SNiP 2.03.11-85, which provides a classification of aggressive environments with the degree of their impact. They can be gas, liquid and solid.
The first include compounds of sulfur, carbon, carbon dioxide and sulfur dioxide, etc. Their aggressiveness is characterized by indicators of type, concentration, temperature, humidity and solubility in the aquatic environment.
Liquid aggressive medium exists in the form of a solution of alkalis, acids and salts. And besides - oil, oils and solvents. The main indicators here are agent concentration, temperature, pressure force and speed. In a liquid aggressive environment, the corrosion process is particularly intense.
Solid aggressive environments include dust, various soils, etc. The indicators of their aggressiveness consist in dispersion, solubility in water, hygroscopicity and humidity. The role of active moisture in a solid medium is especially dangerous to underestimate.
Climatic and geological conditions in which the construction process is being carried out in our country sometimes make it difficult to find optimal solutions that can take into account all types of impact on the physical deterioration of facilities, their durability, efficiency and other indicators. That is why it is important that the operating personnel take into account possible specific impacts on the structures entrusted to them.
How air is affected by physical wear
The negative effects of polluted air, especially combined with increased humidity, lead to accelerated wear, cracking, corrosion and, ultimately, the destruction of any building structure. Placed in a dry and clean atmosphere, concrete, stone and metal are able to maintain their consumer properties for hundreds of years, which may indicate weak aggressiveness or the complete absence of such an air environment.
The most intense air pollutants are fuel combustion products. That is why in conditions of industrial centers and large cities, the rate of metal corrosion is 2-4 times higher than in rural areas, where much less coal and oil products are subject to burning.
Influence on negative temperature wear
Part of the structure (most often it is a socle) is located in an area subject to alternating wetting and periodic freezing. Negative temperature in the absence of special measures leads to freezing of moisture in soils and structural elements and destructively affects the structure. Freezing and buckling of the bases can occur over a sufficiently long period of operation in the case of cutting the soil near the foundation, moistening the latter and other factors. As a result, serious damage to the building is possible.
When designing construction projects, measures are planned in advance for the repair and maintenance of engineering networks and structures. Upcoming deterioration, taking into account the mandatory implementation of the latter, refers to the normal physical deterioration of the building. Based on it, they calculate the normative period during which the building must function safely. For residential buildings, such terms are determined by the capital group.
What is meant by its size?
The definition of physical deterioration implies a quantitative assessment of the technical condition of those elements of which the building consists. It shows the proportion of damage suffered, the degree of loss of the initial characteristics of a physical nature that meet the requirements of operation. Currently, there is a methodology for assessing physical deterioration, according to which the latter is determined by adding up the wear size of individual structural elements, determined according to their replacement cost fractions in the total indicator for the entire building.
A determination of physical deterioration is carried out, resorting to inspection. In some cases, the technique provides for the procedure for opening a number of structures. The percentage of physical depreciation, according to the tables related to this methodology, varies within 5%.
Building wear assessment table
Each degree of the technical condition of structural elements has certain signs of wear located at a certain interval. For example, the operating conditions of foundations differ from those for walls. Accordingly, the data interval in the table is different. All signs of such wear are based on average values. More valuable structural elements are prescribed in the table indicating wear with a lower interval indicator.
The dynamics of depreciation, that is, its change in time relative to the actual time of operation, is of great importance in the process of using the housing stock. Different materials and its structural elements can wear out under the influence of destructive and other factors. It should be taken into account and the objective difference in the degree of environmental impact on a particular structural element. For example, the loads on the outer wall and the internal flight of stairs are incomparable.
Unfortunately, in the framework of this article, we are not able to completely give the composition of the table for our readers - it takes more than one sheet and consists of a huge number of items related to the most different structural elements of the building. As an illustrative example, we can only offer one of its many parts, in this case relating to wall panels.
The relationship between the time factor and the amount of physical wear and tear is quite obvious. The temporary factors include two main characteristics - the life of the building (actual age) of the building and the ultimate service life (durability). The latter, in turn, depends on the period of time during which the supporting structures are able to resist the process of loss of strength. Most often, the maximum service life corresponds to the standard calculated according to the capital group of the building.
Note to ZhEKu
Provided that current repairs are carried out in a timely manner, buildings that have exhausted their standard service life are usually subject to physical wear corresponding to the level of 75-80%. It is obvious that the overhaul and current repairs significantly affect its dynamics, that is, it slows down this process.
When it comes to the efficiency of the organization operating this publication, the assessment of the physical deterioration of the building obtained during the examination, which cannot exceed that contained in the regulatory document, is taken into account. As normal operation, one is adopted in which the whole range of work is performed with timely repair and maintenance of the facility in good condition.
Building wear schedule
If you track physical deterioration over a certain period of time, making the necessary measurements, you can get a schedule for its change, from which we will see the technical condition of the object throughout the entire operational period. Reducing the amount of wear in certain periods contributes to the replacement of individual structural elements (where possible) and timely overhaul.
Analyzing a similar graph in accordance with the rules for assessing physical depreciation, we can consider individual areas with minimum and maximum indicators of this parameter. Moreover, we are talking separately about each of the following operating modes:
1. The zone of normal operation, in which capital facilities are repaired and elements are replaced on time.
2. The zone of maximum deviations, which is characterized by the timely implementation of work on the repair of the main structural elements (roof, hot and cold water supply, heating, sewage).
3. The zone of unsatisfactory operation, when repairs are carried out on time only on two main structural elements.
4. The zone of unacceptable operation when no repair or replacement of elements is carried out.
Example: five-story building
If timely repair work was carried out only on the main structural elements (roof, water supply, heating and sewage systems), the standard service life is reduced by 10%.
If such work was done only on a pair of structural elements, we can talk about a decrease of 21%.
In conditions of natural aging, when repair and replacement of elements are not performed, the reduction of the standard service life of such a building is up to 40%.