Maintenance is preventive in nature. Activities include inspection and works necessary to fulfill the intended function or to sustain the original standard of service.
The maintenance of structure is done to meet the following objective-
- Prevention of damages due to natural agencies and to keep them in good appearance and working condition.
- Repair of the defects occurred in the structure and strengthen them, if necessary.
The Maintenance work is broadly classifying as-
- Preventive Maintenance
- Remedial Maintenance
- Routine Maintenance
- Special Maintenance
1. Preventive Maintenance
The maintenance work done before the defects occurred or damage developed in the structure is called preventive maintenance. It includes thorough inspection, planning the programs of maintenance and executing the work. It depends upon the specifications, condition and use of structure.
2. Remedial Maintenance
It is the maintenance done after the defects or damage occurs in the structure. It involves the following basic steps.
- Finding the deterioration
- Determining the causes
- Evaluating the strength of the existing structure
- Evaluating the need of the structure
- Selecting and implementing the repair procedure
3. Routine Maintenance
It is the service maintenance attended to the structure periodically. The nature of work done and interval of time at which it is done depends upon specifications and materials of structure, purpose, intensity, and condition of use. It includes whitewashing, parches repair to plaster, replacement of fittings and fixtures, binding of the road surface.
4. Special Maintenance
It is the work done under the special conditions and requires sanction and performed to rectify heavy damage. It may be done for strengthening and updating the structure to meet the new condition of usage or to increase its serviceability. It may include particular or complete renewal occurring at long intervals, such as floors, roofs, etc.
Necessity of maintenance
The causes which necessitate the maintenance effects the service and durability of the structure as follows:
- Atmospheric agencies
- Normal wear and tear
- Failure of structure
1. Atmospheric agencies
Rain- It is the important source of water, which affects the structure in the following ways;
Physical- Dissolving and carrying away minerals as it is universal solvent.
Expansion and contraction – The materials are subjected to repetitive expansion and contraction while they become wet and dry and develops the stresses.
Expansion of water – The variation of temperature causes the expansion and contraction absorbed water and affects the micro-structures of the materials.
Erosion – Transportation, attrition and abrasion of the materials is quite evident effect of the water.
Chemical- The water available in nature contains acids and alkaline and another compound in dissolve form acts over the material to give rise, which is known as chemical weathering,
Wind- It is the agent, which transports the abrasive material and assists the physical weathering Its action is aggravated during rains and, when it is moving with high speed, it may contain acidic gases like CO2 fumes which may act over the material and penetrates quite deeply in materials and structure.
Temperature- The seasonal and annual variation of the temperature, difference in temperature in two parts of the materials and the surface of material causes expansion and contraction, this movement of the material bond and adhesion between them is lost when it is repeated. This responsible for the development of cracks and the rocks may break away into small units.
Exploitation or peeling off the shell takes place if exterior layer is heated externally with respect to internal layers. The temperature variation may also cause change in the structure and chemical composition of the material.
2. Normal Wear and tear
During the use of structure, it is subjected to abrasion and thereby it loses appearance a serviceability.
3. Failure of structure
Failure is defined as the behaviour of structure not in agreement with expected condition of stability or lacking freedom from necessary repair or noncompliance with desired use of and occupancy of the completed structure. In field it may result in visual collapse of the structure or even suspension of the services e.g. the collapse of towers, sliding or over turning of dam, settlement of foundation, crushing of columns etc.
1. The causes of failure may be broadly grouped as:
- Improper Design
- Due to incorrect, insufficient data regarding use, loading and environmental conditions, selection of material, and poor detailing.
- Defective Construction
- Poor materials, poor workmanship, lack of quality control, and supervision.
- Improper use of structure
- Overloading, selecting the structure for the use for which they are not designed such as deteriorating environment due to impurities from industrial fuel burning, seawater minerals, chemicals, storage of chemicals, etc.
- Lack of maintenance
- Lack of upkeep, proper protection, precaution, and preservation, deteriorated the structure, which may result in the failure.
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