Wooden truss calculation - Drawings, PP

Contents

Task

1. Building Frame Layout

2. Calculation of glue panel

3. Calculation of the farm

4. Calculation of Farm Nodes

5. Calculation of wooden rack

6. Rack Support Node Calculation

7. Foundation calculation

8. Protection of wooden structures against rotting and fire

Literature

Protection of wooden structures against rotting and fire

Sterilization of wood occurs naturally in the process of artificial, especially high-temperature drying. Heating of wood above 800 C leads to the death of all house mushroom spores present in it.

Structural protection of wood against rotting provides such a mode of operation of structures at which its humidity does not exceed the level favorable for rotting. Protection of the wood of the enclosed premises from humidification by atmospheric precipitation is achieved by complete waterproofing of the roof made of high-quality materials. Protection of wood from moisture by air vapors is achieved by the fact that in rooms with a humidity of 75% and the release of water vapors, its surface is isolated by water-resistant paint materials, for example, PF - 115, UR - 175, etc.

Chemical protection of wood is necessary in cases when it is moistened during operation. Structures used in the open air, in the ground, etc., for example, structures of bridges, masts, piles, etc. Chemical protection of such structures from decay consists in impregnation or coating of their poisonous substances for mushrooms - antiseptics. They are water-soluble and oily.

Water-soluble antiseptics are substances that do not have color and smell that are harmless to humans, for example, sodium fluoride and silicon fluoride. I use them to protect wood in closed rooms, where people can stay and there is no danger of washing out antiseptics with water.

Oily antiseptics are some mineral oils - coal, anthracene, shale, wood creosote, etc. They do not dissolve in water, are very poisonous for mushrooms, but have a strong unpleasant smell and are harmful to human health. These antiseptics are not washed out by water and are used to protect against rotting structures operated outdoors, in the ground and above water. The introduction of antiseptics into the wood is carried out by various methods. Impregnation of wood under pressure is most effective. The wood with moisture content of not more than 25% is kept in the antiseptic solution inside the steel autoclave under high pressure, as a result of which the antiseptic penetrates into it to a sufficient depth. Impregnation of wood in hot - cold baths also gives a sufficient effect at a lower cost. Surface antisepting consists in application of hot antiseptic solution or thick antiseptic paste to wood surface.

Structural protection of wood against fire consists in elimination of conditions favorable for fire occurrence and propagation. To prevent the spread of fire, wooden structures should be divided into parts by fire barriers and fire-resistant areas. Wooden enclosing structures shall not have communicating cavities with the air rod, through which flames that are not available for extinguishing may spread. Ordinary plaster significantly increases the resistance of wooden walls and ceilings to fire.

Chemical protection against fire is carried out in cases where an increased degree of fire resistance is required from enclosing wooden structures, for example, in premises where crowding is possible. It consists in fire-fighting impregnations and painting. For fire-retardant impregnation of wood, substances called flame retardants are used. These substances introduced into the wood, with dangerous heating, melt or decompose, covering it with fire-retardant films or gas shells that prevent oxygen from accessing the wood, which at the same time can only slowly decompose and melt, without creating an open flame and without spreading fire. Impregnation of wood with flame retardants is carried out under pressure in autoclaves, usually with simultaneous impregnation with antiseptics. Protective paints based on liquid glass, superphosphate and other substances are applied on the surface of wood. When heated during a fire, the films swell from the released gases and create an air layer that temporarily prevents fire .

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