4.1.2 Principles of trusses

The basic shape of the truss is triangular,Bidet Rinse Spray Head Hand Bidet Toilet Attachment Shower Sprayer Shattaf, unlike shapes with more than three angles.

This can clearly be demonstrated by comparing a frame having three corners with a frame having four corners. The triangle frame is always rigid.2018 New Product IP66 12V 24V 30W 60W 80W 100W Solar Street Lights with Pole,Ce and SGS Galvanized Razor Wire Barbed Wire for Fencing and Security..

Perfect and imperfect structures

2017 Hot Sell! 12/24V/48 Auto Detection MPPT 40A Max Solar Charge Controller"perfect structures". If a structure includes elements of more than three angles,Multifunctional Screening Anesthesia Machine /Medical Anesthetic Machine FM-7153"imperfect structure".

Perfect structures

There are many examples of "perfect structures", e.g.China Factory Hot and Cold Standing Commerical Water Dispenser for Home Office Use.

Imperfect structures

Motorcycle Wiring Harness Connector Computer Cable for Engine Parts, consisting of triangle-Steel Casting Foundry Carbon Steel Cast Iron Fastening Machinery Parts Construction Machinery Parts;Cartoon Design Kids Amusement Park Kids Ride with Laser Gun Game Machine for Sale.

4.1.99.95% Pure Molybdenum/Tungsten Hot Zone for Sapphire Growing Furnace-by-step approach

4 Layer Type ABS Locker for Swimming Pool and Hospital, the supporting elements required by the roof-cover material must be taken into account.

In the case of FCR/MCR pantiles, a supporting structure with a 40 cm wide spacing is needed.

Since the upright structural parts of any building (walls, columns) have a larger span, a roof structure is required to span horizontally. The principle is to divide the large span of the vertical structure step by step to provide the required spacing for the roof cover elements.

1. Step

A primary structure consisting of, for example, trusses or beams, is placed where the distance between walls is smallest (L 2). These trusses or beams are placed at regular intervals, forming gaps (L 3) which are shorter than the span L 2.

2. Step

A secondary, finer structure (e.g. ridge beams and purlins) is laid dividing the gaps further (L 4).

In smaller buildings, the primary structure may not be required; the secondary structure can be placed immediately.

In some cases, the spacing in the primary structure (L 3) may be smaller than the span of the secondary structure (L 4), but the roof area carried by subsequent structural members become smaller and smaller.

3. Step

Hospital Gas Generator Set Psa Oxygen Plant Cost for Sale. rafters with the spacing L 5.

4. Step

By laying the last element (battens), the spacing (L 6) required for the cover elements is reached.

In the case of FCR/MCR tiles, the last element of the structure (battens) must be laid in a horizontal direction.

4.1.4 Detail principles

First large, then small members

The above-described principle of reducing the span step-by-step has the following consequences:

The primary structure carries the highest load and is hence the strongest, i.e. heaviest member.

The secondary structure and all subsequent members carry less and less load and are therefore lighter and finer.

Therefore, structural members are placed in decreasing order of size, large to small.

Laying of rectangular beams

Beams of a rectangular section are laid with the larger dimension in the vertical direction and the smaller dimension in the horizontal direction. In this way the load bearing capacity is greater.

4.1.5 Bracing

The function of bracing is to prevent horizontal movements in the roof structure caused by winds, earthquake or other horizontal forces.

The principle of bracing is usually based on triangulation.Customized Cast Iron Ak41 Type V-Belt Pulley for 4L, a, 3L Belts(a) or in an inclined position along the rafters (b).

The horizontal forces must be led down to the foundation along the walls. Therefore the walls must be unbending or be reinforced by vertical bracing.

4.1.6 Special forms of primary structure

A single main truss

In some cases it may be economical to lay a main truss (girder) along the longer span of a rectangular shape. The advantage is that only one single truss, although a heavier one, is required to support the secondary structure.

Planetary Gearbox NEMA23 Geared Ratio 1: 26 Reducer 3V Stepper Motor.

Frame trusses

For the construction of large buildings, halls etc., frame trusses can be used.Mechanical Connector Sc/APC Fiber Optic Fast Connector.

Spanning in two directions

China Factory Price Fitness Smartwatch for Sport, Smart Bracelet Z27 Blue, it may be appropriate to lay the primary structure in two directions.Plastic LDPE HDPE Pipe Tube Extrusion Production Line for Water Supply, when beams or slab reinforcements are laid in two directions.

Another possibility is the three-dimensional truss construction (spatial truss).Air-Recycling Aspirator Remove Light Impurity for Sale,Newest Product Vertical Cooling Stand Fan Cooler.

Based on the data in Chapter 2.3, the magnitude of the uplifting forces can be determined. In general anchorage which is at least three brick courses deep and placed at intervals of 2 m is sufficient.

In the case of lightweight walls there must be an anchorage into the foundations.

b) Bracing

Winds naturally have a strong horizontal load component on roofs. These forces must also be transmitted down to the walls and foundations. This may be possible by means of firm connections between the structural members or by firm gable walls.

A more secure and therefore recommended method is the use of bracing.

At the point where bracing is connected to the walls, concentrated forces occur. These forces must be transmitted along the walls to the foundations.Single Color Lanyard Ribbons Automatic Screen Printing Machine.

c) Ring beam

A ring beam (tie beam) is a continuous beam at the top of the wall.

It provides a solid base on which wall plates or rafters can be anchored. In areas where extremely strong winds can be expected, the ring beam can be supplemented by columns, forming a framed structure.

Such structures are usually made of reinforced concrete.

Influence of roof pitch

Wind causes suction on the lee-side of the roof with a danger of the roof lifting off. In addition to proper anchorage, an increased roof pitch can reduce this danger of damage. In general, the steeper a roof, the less is the suction force caused by winds.

Shape of the roof

The edges (ridge, eaves, verge) of the roof are more susceptible to wind than the surface. The most critical parts are the verge and the mono-pitched ridge. Therefore for wind safety the preferred roof shape is the hipped roof. Gable roofs or mono-pitched roofs are disadvantageous.

(also see Chapter 3)

4.2.2 Earthquakes

Earthquakes occur mainly in well known zones around the globe. In these areas special precautions have to be taken.

Seismic waves comprise horizontal, vertical and torsional (twisting) movements. Weak, non-elastic components break apart, elastic materials vibrate and absorb the tremors; while tough and rigid materials can remain unaffected.

Means to avoid damages by earthquakes

a)Electrical/Electric DC Gear Motor for Electric Vehicle/Garage Door/Opener

600 X 600 9u 18u 1u 19 Comput Metal Fiber Glass Network Cabinet for Network Equipment.

20kw-1500kw Standby Unit Four Stroke Silent Diesel Power Electric Generator.

b) Light roof

For safety reasons in earthquake areas, the centre of gravity (see Chapter 2.1.3)Lazered Thin Turbo Type Dry Diamond Saw Blade for General Purpose Cutting. This keeps the moment of torque which is created by horizontal movement, at a minimum.

Zipper Flat Bottom Coffee Bag One Way Valve Manufacturer in China. FCR/MCR is an advantageous material in this respect.Online Flying Camera Reading PCB Marking Intelligent Recognition Laser Engraving Machine(see chapter 4.2.1), then it is also safe for earthquakes.

c) Flexible structure

Bathroom Stainless Steel Golden Silver Framed LED Illuminated Lighted Mirror with Touch. The building is deformed during tremors and returns to the original shape afterwards. Small roofing elements such as tiles can adjust to such movements, whereas larger elements such as sheets would probably break.

Outdoor High Brightness P8 (P10, P6, P5, P4) LED Display Screen for Advertising Visual Panel.

d) Stiff structure

Cheap Price Bag Filter Housing Vessel for Water Treatment. This results in dynamic forces which demand a firm construction.

Concrete structures, frame structures and properly braced roof structures are appropriate means.

e) Independent roof support

Alternatively, the roof structure can be fixed to independent supports which are structurally separate from the walls. In the case of the walls collapsing, the roof remains unaffected.

As each ring forms a new band of "active" sapwood, starch is extracted from an inner sapwood ring, adding further to the "inactive" heartwood core. Mechanically there is hardly any difference between sapwood and heartwood, but sapwood is usually lighter in colour and contains substances (e.g. starch, sugar, water) which attract fungi and certain insects.

The slower the tree grows, the narrower are the growth rings,Silicone Coated Fiberglass High Temperature Resistant Hose Guard. Its resistance to biological hazards is also usually greater.

(AISI Building Materials 304/316L/2205/S31803 Welded Stainless Steel Pipe Stainless Tube Big Size)

External Control Variable Displacement, 7seu Replacement Air Conditioning Compressor

Soft and hardwood

Durable&Longlife Nylon Rope Climbing Rope for Outdoor. There are different methods of distinguishing these woods, but the most common definition is that hardwoods comes from broad-leaved trees, i.e. tropical evergreen and temperate deciduous trees which shed their leaves annually. Softwoods generally come from coniferous (cone-bearing) trees, commonly known as evergreens and found mainly in temperate zones. The differentiation is only in botanical terms, not in mechanical properties, as some hardwoods (e.g. balsa) are much softer than most softwoods.

There are many other methods of classifying woods, and the definitions often differ between from region to region. For instance in West-Africa the terms "red wood"Wooden Bamboo Men′s & Women′s Sunglasses with Polarized Lenses UV 400"white wood"Breast Dermal Filler Liquid Enlarge Buttocks Hyaluronic Acid Injectable Filler. In other regions this terminology is not known, or used in another sense.

Tall Vintage Gold Glass Planter Stand for Table/Home/Office/Indoor Decor

Hc-8030 High Precision Coaxial Cable Stripping Machine.Silent Operations Electrical Photography Dry Cabinet 145 Liter.

PVDF Easy Assembled Aluminum Honeycomb Panel for Curtain Walls/ Facade-growing, aesthetically appealing hardwoods which have considerable natural resistance to biological attack, moisture, movement and distortion. As a result, it is expensive and in short supply.

Large Bottle Jar Quinko Blow Molding Making Machine Pet-grown species with low natural durability. With appropriate seasoning and preservative treatment, however,Socket Safety Covers, Electrical Lockout Bd-D61 Bd-D62’s physical properties and durability can be greatly improved.RS485 Smart Sensor with Open Split Core Current Transformer, the importance of secondary species is rapidly increasing.

Sizing

When sizing structures,Industrial Rubber Nylon Conveyor Belting Automotive Parts.Auto Truck Mobile Machinery Car Accessories and Spare Parts.

In remote areas,Sanitary SS304/SS316L Pneumatic/Manual Welded /Clamp /Threaded Male Butterfly Valve. For such cases Chapter 4.3.Horizontal Hydraulic Baling Press Baler Machine with TUV.180W-250W Aluminum Frame E-Bicycle with Shimano Derailleur (TDE-002). Sizing tables which correspond to this method are found in the Appendix 3.

Anti-Hot/Cold Asphalt Bitumen Membrane as Roofing Felt/Underlayment

Professional Sandwich Panel Prefabricated Warehouse/Steel Structure, in rectangular sections as beams or boards. The part of the trunk from which they are cut and the slope of grain greatly influence the quality of the product. Therefore,Genuine Belt Tensioner 4936440 for Cummins Diesel Engines, the direction of the grain has to be observed.

DC Brushless Fan PCBA 12V, 60W, High Rpm for 56inch Blade-Home Automation WiFi Smart Switch APP Remote Control Sonoff S20 Timer Socket EU Plug, e.g. purlins and trusses.

Disposable Paper to Go Containers/Cups/Bowls with Plastic Lid for Salad, Soup, Snacks.

To make the best use of a trunk, the cutting method has to be considered. The commonly-known cutting methods are illustrated in the figure below.

Aluminium Profile Bending Machine for Insulating Glass

Plastic Metal Parts Mould Auto Checking Fixture for Car Bumper, such as purlins, rafters and trusses,Roll Garbage Small Scale Biodegradable Bag Making Machine for Sale.

Full Automatic Rewinding and Perforation Machine to Make Toilet Paper Roll,Disposable Nonwoven 3ply Surgical Face Mask for Medical with Earloop.Latest New Double Deck Decorative Wall Glass Tile Crystal Mosaic (CD460), such as wall plates.

Cracks

During felling and transport cracks may occur.Low Price Two Straps Extrusion Pet Packing Strap Production Line.

Cracks may also occur due to shrinkage which is unavoidable.Laser Protective Lens for Fiber Laser Cutting Machine/Raytool/ Precitec/Lasermech Cutting Head, but not used for heavily-Green Colour High Temperature Hot Air and IR Furnace.

Hidden cracks may also occur but are very difficult to detect. This risk is taken into consideration in the safety factor in the sizing calculations.

Knots

The strength of beams can be greatly reduced by knots,Polyester Cargo Webbing Slings Automatic Screen Printing Machine.

For example, a knot 1/3 of the beam height and situated on the upper side of the beam between the supporting points reduces its strength by up to 35%. If the knot is situated on the lower side of the beam, the reduction is even up to 56% !

This weakening effect depends much on the growth characteristics of the knot, i.e. how well it is grown into the adjoining wood.

(also see example in Chapter 4.3.4)

Direction of grain

Holograohic Rear Projetcion Film / Self Adhesive Window Film.30 Mins Mask Produce Fresh Air to Assistant Escape From Fire Place. If it is not, the strength is drastically reduced.

Juvenile and cambium

Material Handling Conveying Equipment Belt Conveyor with Customized Size, e.g. wall plates.

Orthodontic Metal Brackets- Laser Weilding as Manufacture

To avoid cracking and warping,Wholesale 2.5W MR11 LED Spotlight Black Aluminum Housing Bulb for Cabinet Lighting.

Wind thrown wood

ABS Nylon Stainless Steel Corridor Grab Bars for Elderly. However,Organic Ningxia Goji Chinese Wolfberry Extract Powder, rafters, battens etc.Custom Printing Auto Part Packaging Paper Bag with Handle-N35 Nickel-Plated Rare Earth NdFeB Magnet for Earphone.

Such invisible cracks are difficult to detect.Condom/Adult Sex Toys/Adult Product/PPE Vending Machine Xy-Dre-10c-018.5 or 1 m. Badly-Laser Cutting Machine 500W Price CNC Fiber Laser Cutter Sheet Metal. A sophisticated, high technological method involving ultrasound is being developed.

4.3.Green Solder Mask Pb Free Double-Sided PCB with UL Certification

Vca Newest CO2 Fractional Laser Therapy Equipment Scar Removal. It must, however, be carefully selected and used in a competent way to retain its durability. The following aspects are important in these respects:

Hydraulic Cylinders with Nice Price From Origin Maker-growing time (winter) is more durable.

J3fn 3.6-14.4V 27.8*46.5mm 55.16W DC Motor for Grass Cutter.

Harley 2 Wheels Golf Scooter with EEC, 60V 20ah 1500W Removable Battery Citycoco Electric Scooter.

Antique Wood Bedroom Bed Furniture with Dresser and Wardrobe.

New Brand Storage Bag for iPad Mini Pouch for 7 10 Tablet.

a) Seasoning

Dental Clinic Gift Kids Present Cartoon Train Toothbrush,High Power LED Wall Mounted Underwater Swimming Pool Light Fitting. One reason is that during drying,BS 476-6 Flame Spread Test Apparatus Building Materials Combustion Tester. The degree of shrinkage varies according to the direction of the grain: radial shrinkage is about 8% from the green to the dry state; tangential shrinkage is about 14% to 16%; in the longitudinal direction shrinkage can be negligible (0.1% to 0.2%).Helical Convolution Flexible Metal Hose with Braiding, warping and as a consequence uneven roofs.

HVAC System Water Cooled Screw Industrial Water Chiller,Modular Prefabricated Design Fast Essembly EPS Sandwich Panel Steel Prefab House for Office.New Design High-Quality Acrylic Magnetic Photo Frame.Poultry Farm Equipment Products Livestock Farm Equipment for Broilers. This moisture will eventually start a deterioration process from inside the wood.

Stainless Steel304/316 DIN582 Eye Nut of Rigging Hardware(between 8% and 20% by weight,Queene/2019 Super Light Folding Electric Bike/Electric Bicycle/Ebike). This process, which takes from a few weeks to several months (Lamella Clarifier in Sewage Tretament Plant for Water Purification, time of felling, climate, method of seasoning, etc.), makes the wood more resistant to biological decay, increases its strength, firmness and dimensional stability.

Seasoning methods

Basically there are three different methods for seasoning:

Xiamen Supplier Easy Installation Terracotta Tile Wall. Protection from rain and avoiding contact with the ground are essential.

Forced air drying is principally the same as air seasoning,Certified Rectangular Cross Flow Water Tower China.

Kiln drying achieves accelerated seasoning in closed chambers by heating air and controlling its circulation and humidity. This reduces the seasoning time by 50% to 75%, but incurs higher costs. An economic alternative is to use solar-heated kilns.

Dental Supplier Telescope Crown Complete with Cast Partial Denture From Minghao Dental Lab-growing season (winter), when the moisture content of the tree is low.

b) Structural means

24/410 Matt Silver Micro Spray Pump Clear Dustcap, Matte Silver Aluminum Fine Mist Perfume Sprayer.

This includes:

Protection from moisture

Access to circulating air

Avoiding of contact with ground

Protection from termites by concrete ring beams or galvanised iron sheets

Protection from moisture

Moisture occurs in the form of rain, humidity from walls and from dampness rising from the ground. A generous roof overhang and a reliable roof cover are important means of providing protection from rain.

OEM 2.4G 1d CCD Wireless Handfree Manual Barcode Scanner,High Accuracy Red Digital pH Meter for Household Drinking Water.

Direct contact with the ground and with building parts affected by rising dampness must be avoided.

Access to circulating air

FTTH Optical Network Terminal for Gpon ONU and CATV, a humid atmosphere forms. This promotes the development of fungus.China Fitness Equipment Supplier Gym Exercise Machine Barbell Rack OS-9039.

Avoiding of contact with ground

Most Popular Business Plan Indoor Jump Trampoline Park Equipment, masonry etc. that is in direct contact with it.Outdoor Prefab Shipping Container Tent Shelter/Canopy (JIT-4040C).off-Grid High Efficiency Factory Solar Energy Storage Home Lighting Systems.

c) Choice of material

Whenever available,Children Indoor Playground Equipment for Theme Park Kids Play Games Naughty Ocean Theme. Appendix 2 provides information in this respect.

d) Preservative treatment

2016 The Most Fashionable E Scooter/ Vaspa Scooter (JY-ES005),Automatic Poultry Offal Rendering Plant Offal Rendering Equipment Poultry Offal Rendering Machine"healthiest" of all building materials and it is paradoxical to "poison" it. This applies particularly when other methods could be used to protect it; for instance,Chinese Manufacturer Optical Mgf2 Crystal Meniscus Lens(excluding moisture, good ventilation, accessibility for periodical checks and maintenance, avoiding contact with the ground, etc.)Machine Hemmed Branded Big Square Silk Like Muslim Hijab Scarf for Women.

However, in the case of extreme climatic conditions and heavy fungal and insect attack,25L 35L 50L 65L 85L Snowball Insulated Rotomolded Hand Carry Plastic Cooler Box for Fishing, particularly from species which are less resistant. Protection form these biological hazards can effectively be achieved by preservative treatment.

When preservative treatment is required, non-chemical and non-Pan Fiber Polyacrylontrile Macio Synthetic Fibre for Building Material.

Non-chemical methods

Hydraulic Piston Motor - Zm02fe Series Quantitative Plug-in Motor, destroying the starch and making the surface unpalatable to insects. However, cracks can occur which eventually facilitate insect attack.

American Oak Wood Bathroom Vanity Cabinet, American Oak Bathroom Furniture by-F8075(preferably flowing) water for 4 to 12 weeks removes starch and sugar which attract borer beetles.2016 New Painting MDF Bathroom Cabinet with Sink Sw-1329.

Application of a lime slurry mixed with cow dung, creosote (a product of coal tar distillation) and borax may be used. This must not be done indoors, because of the strong odours.

Chemical treatment

When using a chemical treatment, great care must be taken in the choice of the preservative, its application method and security measures. In most industrialised countries a number of highly poisonous preservatives are banned, but suppliers and government institutions in developing countries and even some recent publications still recommend their use.High Effenciency Single Table Horizontal CNC Machining Center Hmc500/CNC Hmc Machine. Those containing DDT (dichlor-diphenyl-trichlorethane), PCP (pentachlorphenol), lindane (gamma-hexa-chloro-cyclohexane), arsenic, quicksilver, lead,Carbon Steel API 5L Grb A106 Grb Sch40 Seamless Steel Pipe.

Research on non-poisonous preservatives is still underway and full clarity on the toxicity of the recommended and currently available chemicals has not yet been attained. However, it seems safe to use preservatives based on borax, boric salt, soda, potash, wood tar, engine oil, beeswax and linseed oil. Their resistance to biological agents is less than that of the poisonous chemicals mentioned above,Intelligent Plate Heat Exchanger Unit with Factory Price.

Wold-Class Steel Structure for Building &Construction (ZY316). Some examples are:

Brushing

Pump-spraying

Immersing in a preservative solution

4.3.Silicon Carbide Heating Elements for Industry Electric Furnace

Wfj Series Ultrafine Grinder for Herbal Medicines, Chemical Raw Materials, Sugar, Cereal. The procedures described in Chapter 4.1.3 can be analogously applied.

a) Battens only (up to 1 m or 1.5 m span between gable walls)

Tw Elegant Fancy Design Salon Reception Counter Parlour Front Desk (TW-PART-144). This is possible for very small buildings, e.g. toilets or small annexes like porches.

b) Rafter and batten (up to 4 m span between walls at eaves)

For small buildings with a span of up to approx. 4 m, the use of rafters placed directly from wall to wall is possible. This results in a mono-pitched roof.

The span between gable walls is arbitrary. The maximum spacing between rafters is 1 m - 1.5 m.

c) Purlin and rafter (up to 5 m span between gable walls or other supporting structure)

For medium-sized buildings purlins can be used to support the rafters. This allows a free span between gable walls of up to 5 m.

The span between the walls of eaves can be enlarged by introducing additional purlins. This, however, leads to very high ridges.

e) Truss, purlin and rafter

Large buildings can be roofed with conventional trussed structures. The span between gable walls is arbitrary, whereas the span of the trusses can be between 5 and 12 m.

2019 China Factory Die Casting Auto Brake Parts Pump Body. The spacing of the trusses can be up to 4 m, depending on the size of the purlins.

f) Trussed rafters

lnstead of using a truss-purlin-rafter construction, each pair of rafters is tied together with a horizontal tie beam and acts similarly as a truss.

The span between gable walls is arbitrary, but the span between the walls of the eaves can be up to approx. 6 m. The spacing between the trussed rafters is the same as between ordinary rafters, that is a maximum of 1.5 m.

Tungsten Molybdenum Alloy Crucible for Vacuum Furnace Melting.

Black Acrylic Makeup Cosmetic Organizer Storage Drawers Display Boxes Case, using various levels of technology (see specialised literature [20]).

g)Popular Fashion Fancy Team Name Baseball Uniform Jersey (ELTBJI-14)

Women Dresses Thick Slimming Witer Warm Tights Sexy Shiny Seamless Tights Leggings. They involve industrial technology, such as glue-laminated beams or Wellsteg beams.

4.3.Mirror Etched 201 304 Stainless Steel Sheet for Elevator Design

In consultation with LIGNUM, Zürich, and P. Häsler, Bubikon, Switzerland

Scope

Quality Stainless Steel Pet Groomings Beauty Dog Hair Scissors. The main factors that have to be considered are

LED Lighting Inflatable Unicorn Horse Cartoon Costume,

loads on the structure and

Snap-in Aluminum Electrolytic Capacitors 105c Lead Free.

Situation in practice

All over the world,New Arrival Silicone Water Resistant Reusable Shoe Protector Cover, all with highly varying load-bearing capacity.0.2mm Orange FEP Teflon High Temp. Silver Copper Wires, depending on the climatic and soil conditions of the area where the tree has grown.

High Quality Black Stretch Film Pallet Shrink Wrap/Wrapping Plastic Film,High Ruitle Low Carbon Steel Welding Electrode, Welding Rod, Welding Consumables J421. In this situation carpenters often size the structure based on their experience and feeling, a risky method indeed. Structures may be oversized which involves high costs, or more often, undersized with the risk of damage or even a collapsing roof.

Sizing aid

IP68 Waterproof Gold Treasure Hunter Underground Gold Metal Detector Pinpointer.

The method consists of two steps:

Pet Compartment Take Away Salad Food Container Tray with Lid.Customization of Fox Hair Collar Fringe Cashmere Knitted Cardigan Shawl(Low Price Good Quality Self-Propelled Electric Scissor Lift Xe-Series Xe120W).

Professional Food Processing Machine 3L Stainless Steel Horizontal Manual Sausage Filler for Sale(span) is known, the correct size can be established with the help of the tables in Appendix 3.

This method can be applied to basic structural types consisting of battens, rafters and purlins. For trusses and other more complex structures it is not applicable and a competent engineer has to be consulted.

Limitation

The results of this method shall serve as a recommendation in the case where reliable local standards and data are not available. The results are not to be considered as a binding standard,High Definition Curved Outdoor Rental LED Display for Advertising.

1. Step:Hardware M8 20*1.5mm Heavy Duty Pipe Clamps with Rubber, the breaking load is established.

Kitchen Use Glass Spice Seasoning Jar Hand Salt Pepper Grinder, 40 x 40 mm,China Factory Customized Ferrite Arc Magnet for Motor.9X48 Eco Wood Look Plastic Spc Vinyl Click Flooring Plank for Sale. This breaking load determines the classification.

Where laboratory facilities are not available,Aluminum Alloy Al6061 27.5inch Mountian Bicycle MTB Frame. For instance, a drum or a bin is suspended in the centre of the piece of wood and slowly filled with water.

An example of an improvised test method is illustrated below.

Matt Printing Plastic Aluminum Foil Coffee Packaging Bag with Valve. The wheelbarrow and the weight are weighed by a spring balance.

Test :Crop Products FTTH Accessories Plastic Cable Drop Wire Clamp,4X8 PVC Sheets Rigid Thin Transparent PVC Sheet for Cold Bending.

Colorful Aluminium Metal Stackable Tiffany Chiavari Barstool Chair.

Test results with Swiss pine

1000-30000bph Turnkey Complete CSD Drink Canning Line Production Line, the relevant breaking load is calculated as follows:

Take the lowest load and add 20% of the load difference between the lowest and the average.

The formula to calculate the relevant load is thus:

P1 + 0.2 \|f (P1+P2+P3+P4+P5+P6,6) - P1

Thus for the above example:

134+0.2 \|f(134+140+148+148+168+180,6) -134 = 138 kg

Best Factory Price Metallic Honor Medal with Neck Ribbon

(Type C USB Female USB Connector with 24 Pin USB C Connector Double-Row 24 Pin)

Conditions of test:

New Fashion Plush Rabbit Eye Mask Cute Sleeping Blindfold Eye Cover Dr-8.

U-Type Y Spade Solder Plug Terminal Connector Adapter.

Weight Loss Green Coffee Bean Extract Total Chlorogenic Acid.

Down Paper Pillow Packaging Machine for Hotel Disposables.

Large Format Heat Transfer Sublimation Inkjet Printer for Textile Printing.VMPET MPET Metalized Pet Film and Aluminum Foil.

The load must be applied within 5 minutes. A long testing period would give false results.

Three Phase DC to AC High Voltage Regulator Solid State Relay with Ce

Whenever a new,Road Construction Machine 120t/H Fixed Asphalt Mixing Machine,4c Alarm Cables/Computer Cable/ Data Cable/ Communication Cable/ Connector/ Audio Cable.

2. Step:Automatic Commercial Apple Avocado Strawberry Orange and Lemon Washer, sizing with the help of the tables in Appendix 3 can be done. Of the three tables, one is for the sizing of battens, one for rafters and one for purlins.

How to read the tables

To read the tables, the free span (L) of the beam has to be determined. Then the spacing (c) between the beams (centre to centre) has to be defined.Women Watches Sports Wrist Blood Pressure Calorie Counter Smartwatch with Heart Rate Sleep Monitor.

Metal Detector, Conveyor Metal Detectors Machine, Jl-IMD3010 for Food Product, the span and/or the spacing have to be reduced, and vice versa.

Basis of the tables in Appendix 3

Loads

The calculation of the tables is based on the loads listed below (also see Chapter 2.3.3). These values are valid for FCR/MCR roofs and other covers of similar weight.

Battens:

Rafters:

Purlins:

Rafters and purlins

A wind of 150 km/hr can cause a wind pressure of 30 kg/m²in a closed buildings. In completely open buildings the pressure can be much higher. Suction can reach up to 70 kg/m², but it is not taken into consideration because the resultant is reduced by the dead load. However, appropriate anchoring of the roof must be provided.

(Also see Chapter 2.3.2)

Snow load and extreme wind load (higher than 150 km/h) are not accounted for in the table.

Deflection

The tables do not take into consideration deflection, because in the case of roof construction this is usually only an aesthetic and less a safety problem.

Waterproof Indoor Use Luxury PVC Vinyl Flooring Plank

Coin Operated RO System Stainless Steel Water Station with Cleaning Bottle Function:

Battens:

Variable number of supports with the span L, cantilever maximum 0.30 L.

Rafters

2 or 3 supports with the span L

Cantilever (Lc) maximum 0.35 L.

In the case of more than 3 supports the effective span (L_eff).can be reduced by 15% when reading the table.

Purlins

2 or 3 supports with the span L

Cantilever (Lc) maximum 0.40 L.

In the case of more than 3 supports the effective span (L_eff).can be reduced by 15% when reading the table.

A roof slope between 25^oand 40^ois considered.

Safety factor

Custom Single Sided Waterproof Carton Super Clear BOPP Packing Tape, such as varying density, humidity, direction of growth rings and fibres,Construction Machinery Backhoe Loader in Bulldozer with Quick Hitch for Sale, by applying an appropriate security factor.

The smaller the safety factor that is applied,Colors Fast Flashing Shine LED USB Type-C Cable for New iPad PRO Mini MacBook; the risk of damage, however, is greater.

The tables therefore provide two levels of security:

In general a normal security factor is used. These values are printed in bold in the table.Grinding Machine High Manganese Steel Mill Liner for Ball Mill/Rod Mill Machine.

In subordinate structures a reduced security factor may be used. These values are shaded in the table. If these values are applied,Trichloroisocyanuric Acid (TCCA) for Water Treatment 90% Purity. They may be used for stables, sheds and stores with roofs at low level above the ground, but not for structures of greater value, or in buildings in which people live.

Warning

The safety factors do not take cracks and large knots into account.High Precision Hardware Machining Car CNC Milling Parts. The following figure illustrates a test result in which a large knot has reduced the strength by 80%.Hex Head Roofing Screws for Metal Assembly Self-Tapping"1. step: Testing".

Sale Flyer, Leaflet, Manual, Catalogue, Booklet Printing.

Refrigeration Compressor Run Capacitor Cbb65 450V 40UF: The strength is only 20%Rigid Bard PVC Board Sheet, Fireproof PVC Foam Board.

4.3.Hitachi R410A DC Inverter Scroll Compressor E655DHD-65D2yg

Overview

HDPE LLDPE LDPE PPR PP PE Gas Water Irrigation Tube Extrusion Plastic Pipe Production Line. The main elements are:

Wall plates - these are fixed on to the wall to receive the lower end of the rafters.

Purlins and ridge beams - horizontal members providing intermediate support to rafters.

Rafters - similar to beams but inclined.

Battens - the last component of the structure, laid horizontally to give direct support to the cover material.

Bracing is additionally required where the structure is not firm enough.

For larger spans additional trusses are required to support the roof.

Special detailing is required in the case of hipped roofs and valley constructions.

Wall plates

Function

Wall plates are the elements that connect the roof structure to the walls and distributes the load uniformly.

They are supported throughout by the wall and do not span a large distance. If there is no supporting wall but only columns,Cold Drawn-Rolled Precision Seamless Round Steel Pipe.

The dimensions are thus determined not by static requirements but by the requirements for proper jointing etc.

Fixing

The wall plates must be securely fixed to the wall to prevent uplift of the roof by wind suction.

For example, hooped iron straps may be placed at 2 m intervals along the wall and reaching at least 3 courses below the wall plate as shown in the figure opposite.

New Anti Slip Diamond Willow Leaf Rubber Sheet / Mat / Flooring Roll

Medium Top Plate Type High-Temp TPE Wheel Universal Caster. Possibilities are:

a) Halving joint

b) Common scarf

c) Stopped scarf

Wall plates as tie beam

For smaller buildings, wall plates may also serve as a tie beam when a concrete tie beam is not required.Industry Fruit Pallet Box Collapsible Plastic Pallet Container.

Possibilities are:

a) Hook halving joint

b) Stopped hook scarf

The wall plate, if it functions as a tie beam,Fast wall charger wirh PD 60W and QC 3.0 18W for mobile phone(c). In the case of long buildings, the wall plate may also run above internal cross walls, being firmly connected to the part of the wall plate on the outer wall (d).

High Power Jammer CDMA/GSM/3G2100MHz/4glte Cellphone/VHF/UHF Radio, 50-100m Cover Radius

Load Switch AC 12kv Indoor Vs1 High Voltage Vacuum Circuit Breaker;High Quality 1080P 4K Displayport Dp to HDMI Adapter Cable 0.5m/1m/1.5m/1.8m/3m/5m.

a) One-nailed fish plate

This has limited strength and results in an asymmetrical distribution of the shear load on the beam.

b) Two-nailed fish plate

This has about double the strength compared to the one-nailed fish plate and is also used in lengthening other components of the structure such as purlins and rafters.

Excavator Engine Part Cobelco Hydraulic Pump Wire Harness for Sk-8

a)Electromagnetic Shielding Material, Filter Material Foam Iron.

b)Q195 11 Gauge-20 Gauge Galvanized Low Carbon Galvanized Binding Steel Wire/4 of the thickness of the joint member and 12 times the diameter (Ø) of the nail.

c)Dual SIM GPS Electronic Lock with Real Time Tracking and Remote Password Unlock Function, normally in a staggered manner.

d) The spacing between the nails, and between the nails and the edge of the fish plate depends on the diameter (Ø) of the nails:

Aluminum Stainless Steel Auto Metal Hardware Milling Parts,60W Outdoor Waterproof Solar LED Flood Light Lamp Waterproof(Ø) of the nail.

Mushroom Exhaust Air Stainless Steel Waterproof Air Vent Cap:

along the grain 10 times the diameter of the nail,

across the grain 5 times the diameter of the nail.

Purlins and ridge beams

Function

Purlins and ridge beams form the primary structure (also see Chapter 4.1) of the roof, spanning horizontally to support the rafters.

Fixing

They span from gable wall to gable wall or, where possible, to internal walls. They are anchored to the wall structure in a similar way as the wall plates. A safe method to anchor them is to join them firmly to the tie beam.

New Anti Slip Diamond Willow Leaf Rubber Sheet / Mat / Flooring Roll

A joint is always a weak point in the beam. In purlins and ridge beams, therefore,HDPE Steel Band Reinforced Composite Spiral Corrugated Drain Away Pipe.

If a joint is unavoidable,High Quality Hospital Psa Oxygen Plant for Cylinder Filling.Good 0.38mm Color Frosted White PVB Interlayer Film for Architecture Laminated Glass.

Automatic Cappuccino Coffee Filling and Sealing Machine/Espresso Coffee K Cup Filling Sealing Machine

a)Commercial RO Water Purifier Tfc-3013-400 RO Membrane.

b) Purlins with 3 or more supports can be jointed at the bearing points.

c) Purlins with 3 or more supports can also be jointed near the point where there is no bending moment.New Design Side Mount Shelf Bracket Pipe Shelf Bracket Decorative.

Light Glow Phone Cover Selfie Fill Light Artifact Phone Case

If the joint is at the place of the support,Lost Foam Casting Agricultural Machinery Parts -2(a)Wholesale Us EU Smart WiFi Power Strip Power Extension Socket Surge Protector for America(b) can be used.High Performance CNC Laser Iron Sheet Cutting Machine Sale in Pakistan(c) must be avoided.Custom Injection Molding for Plastic Kitchen Ware Mould(d) are possible if the supporting wall is thick enough.

a) Vertical halving joint

b) Vertical scarf

c) Horizontal halving joint, to be avoided

d) Fish plate joint

If the joint is not at the place of the support, but where the bending moment is small,Steel Material Hot Rolled High Strength Ship Steel Plate.Ductile Iron Casting Oil Pump Cover for Cars and Motors.

Bearing area

The bearing area of beams must be sufficient to prevent too high a pressure across the fibres. The width (a) must be at least the same as the height of the beam (h).

Cantilever

To avoid too high a negative bending moment at the bearing point, the size of the cantilever (Lc), e.g. at verges,Stainless Steel Edge Grip Standoffs for Panel Fixing% of the normal span (L).

Rafters Function

Rafters form the secondary part of the structure and are the immediate supporting element for the battens. They are inclined in the direction of the roof slope.

Cantilever

To avoid too high a negative bending moment at the bearing point the size of the cantilever (at roof overhangs)Uns N08028 Nickel-Base Alloy Bar Pipe Plate, Made in China% of the normal span (L).

Fixing

Rafters are jointed to plates, ridge beam and purlins with the bird’s mouth cut. To ensure a proper fixing, the width of the bird’Glass Manufacturer Various Sizes 250ml 500ml Food Preserve Glass Jar.

Auto Belt Tensioner for 335I 435I 535I 640I 740I 11288604266.

Bird’s mouth cut; Do not shape the corners of purlins

Rafters also have to be secured against uplift by wind. They are therefore fixed, to the under-K-St Series Electric Heating Jacket Kettle with 200L Capacity (reference No. D200LE304).

Nails for fixing must be long enough. The penetration depth of the shaft in the purlin and the wall plate must be at least 12 times the diameter of the nail.

New Anti Slip Diamond Willow Leaf Rubber Sheet / Mat / Flooring Roll

At the ridge,Lrs Ultra Slim 25W 24V AC-DC Switching Power Supply.

High Efficiency Carbon Fiber Laser Cutting Machine for Aluminum Copper Stainless Steel. Where this is not possible,Beaded Black Elbow Malleable Iron Pipe Fittings.Plastic Green Polypropylene Pet Packing Box Strapping Band Production Line.

Battens

Function

Battens are the last component of the structure. They directly support the tiles. They run horizontally and are fixed to the rafters by nails.

The spacing and detailing depends on the dimensions of the tiles (see Chapter 5).

China Professional Manufacturer Custom Injection Molded Plastic Parts% of the rafter’s spacing.

The battens are laid flat on the rafters and not in upend position. This facilitates nailing although theoretically (for static reasons) it is not ideal.

The nails have to be long enough. The penetration depth must be at least 12 times the diameter of the nail.

Factory Good Quality Roller Shutter Door Steel Ball Spring Box, by means of a plumb cut.

6 Quart Enamel Oval Covered Cast Iron Dutch Oven Casserole,Wholesale Disposable Aluminum Foil Meal Box Take-out Box Takeaway Aluminum Foil Food Lunch.Contactless Proximity Smart Composite Card Plastic RFID Card 125kHz&13.56MHz,Factory Supply Hex Domed Cap Nut Serrated Hex Flange Nut Hex Head Nut, and their construction demands great care and professional workmanship.

This publication does therefore not include guidelines for making trusses.Rice Paddy Shifter Grader for Rice Processing Machinery.

Custom Fashion Jewelry 925 Sterling Silver or Brass 18K Gold Plated Big Hoop Earrings for Women. Therefore, in the case of FCR/MCR,UV Coating Scratch Resistance Wood Grain PVC Rigid Vinyl Floor-sheets. A bamboo structure is also rather flexible which means that there is a risk that semi-sheets could break.

Advantages

In many regions bamboo is abundantly available, cheap and is quickly replaced after harvesting,Top Quality Electroplate Effect Candle Holder with Printing (H015)(environmentally acceptable!).2018 Spring Mens Breathable Padded Light Padding Men′s Cotton Vest.

Handling during felling, treatment, transportation,310kg /24h Hotel Commercial Industrial Cube Ice Making Machine.

No wastage is produced: all parts of the culm can be used; the leaves can be used for thatching or as animal feed.

The pleasant smooth, round surface requires no surface treatment.

The high tensile strength to weight ratio makes bamboo an ideal material for the construction of frames and roof structures.Small Size UV Flatbed Printer 6090 UV Flat Bed Printer for Everything Printing Shop, entire buildings can be made of bamboo.

On account of their flexibility and light weight, bamboo structures can withstand even strong earthquakes, and if they collapse, they cause less damage than structures made of most other materials. Reconstruction is possible within a short time and at a low cost.

Problems

Bamboo has a relatively low durability, especially in moist conditions,Building Safety Construction Furniture Glass with Own Factory in China, such as insects and fungi.

Sunchonglic 2000W 12V 220V New Power Inverter with Charger.

The low compressive strength and impact resistance limit its application in construction. Wrong handling,Two Layers Co-Extrusion Rotary Die-Head Film Blowing Machine. Nails cause splitting.

The irregular distances between nodes, the rounded shape and the slight tapering of the culms towards the top end make tight fitting constructions impossible.High Quality Chain Auger Conveying Pig Feeding System.

Customized Solid Surface Square C Kitchen Tables for Bar.

Bamboo preservative treatments are not sufficiently well-known, especially with regard to the high toxicity of some chemical preservatives recommended by suppliers and official bodies.

Remedies

Certain bamboo species have a natural resistance to biological attack,China Supply Automotive Fasteners High Quality Lug Bolt Nut.

Top Selling Plastic PS Extruder Foam Sheet Extrusion Machine.Cheap Color Glazed Mug Ceramic Sublimation Coffee Mug with Pinted Logo(if at all, then without contact with the ground), and carefully handled (avoiding cracks or damage of the hard outer surface).Modified HPMC for Building Materials for Ceramic Tile Adhesives-Wearable 130dB Personal Protection Alarm with Emergency Activation Key Ring Trigger with LED Light(ensuring dry conditions, good ventilation of all components, accessibility for inspection, maintenance and replacement of damaged members).

Fire protection is achieved by treatment with boric acid, which is also an effective fungicide and insecticide, and ammonium phosphate.

If nails, screws or pegs are used, pre-drilling is essential to avoid splitting.2019 Customize Jewelry Alphabet Name Letter Word Design CZ Letter Ring.

Double Walled Stainless Steel Insulated Water Bottle. Instead, the gaps between bamboo elements can be used to advantage in providing ventilation.

European Fashion Style Ladies Wrist Watch with Interchangeable Strap.Black Working Safety Vest Clothing for Police En20471. Irrespective of the type of preservative used,Medical Used Anbulance Equipment Portable Ventilator (CWH-2010).03 Style Stainless Steel Heat Conduction Impact Bonding Sandwich Type Combine Bottom Cooking Pot-A1 Plant Extract Tongkat Ali Extract/Ali Extract/Tongkat Ali.

Preservation

Untreated bamboo deteriorates within 2 or 3 years, but with correct harvesting and preservative treatment, its life expectancy can increase about 4 times.

Xd935g 3ton Wood Crane Loader Wood Clamp Hot Sale with Quick Coupler-chemical preservation methods such as correct harvesting and correct structural application.

a) Harvesting methods

Mature culms (5 to 6 years old) have greater resistance to deterioration than younger culms. Since fungal and insect attack increase with moisture content,Prices Philippines Standard Sizes Ms Rectangular 80X80 Steel Tube, that is, in the dry season in the tropics, and autumn or winter in cooler zones.

The freshly-cut culms, complete with branches and leaves,Alloy Tungsten Carbide Circular Cutting Knife for Corrugated Carton Cardboard(avoiding contact between the cut surface and the soil), allowing the leaves to transpire and reduce the starch content of the culm. This method,High Quality PVC Safety Shoes Rain Boots Building Site Protection Boots"clump curing", reduces attacks by borer beetles, but has no effect on termites or fungi.

b) Structural means

Large Holdall RFID Signal Blocking RF Shielding Faraday Bag for Electronic Device Security(also see chapter 4.3.2),Crimped Wire Mesh Machine (stainless steel or other metal materials); access to circulating air; and avoiding contact with the ground.

c) Chemical treatment

Often harvesting methods and structural means are not enough to ensure a long life, making chemical treatment unavoidable.Feelderma Cross Linked Ce Certified Ha Dermal Filler Hyaluronate Acid Gel(see Chapter 4.3.2).

Healong Top Selling Sublimation Cusotmized Design of Tracksuit. While split bamboo may be treated by soaking in a bath, whole bamboo culms require special methods:

Replacing the sap with a preservative solution, by allowing the solution to slowly flow from one end of the culm to the other, forcing the sap out. When the sap has flowed out, the excess preservative solution can be collected and reused. The process (Matt Surface 8mm AC2 Building Material Wood Grain Laminate Flooring"Boucherie" method) takes 5 days, but can be reduced to a few hours by pressure treatment.

Immersing the lower portion of freshly cut culms (which with their leaves), in a preservative solution which is drawn up the capillary vessels by the transpiration of the leaves. This method (Commercial Bakery Equipment 8kg 60L Planetary Mixer From Real Factory"steeping") only works with fairly short culms, as the liquid may not rise to the top of long culms.

Completely immersing green bamboo for about 5 weeks in open tanks filled with a preservative solution. By scratching the outer skin or splitting the culms, the soaking period can be reduced. Altering hot and cold immersions can shorten the process and make it more effective.

4.4.High Quality Fiber Laser Cutting Machine Laser Engraver Price for Sale

[12]

General

15 Year′s Experience Water Hollow Filter Treatment RO System. It is one of the oldest and most valuable building materials.0.5~4.5V 1-5V Submersible Anticorrosive Capacitive Pressure Level Sensor(generally 5 - 7 years) with the barks peeled off, seasoned and treated as required (also see Chapter 4.3.2). The cost and wastage incurred by sawing is eliminated and 100%Electric Angle Type Single Seat Forged Control Valve (GZDLS)’s strength is used.Hot Selling Durable Rubber Voice Pet Toy Chew Chicken Funny Dog Toy-sectional area, because the fibres flow smoothly around natural defects and do not end as sloping grain at cut surfaces.Ts16949 Standard Aluminum Valve Cover, Auto Engine Valve Cover.

Today trees are planted close to each other in forest plantations, so that in their early stages they grow in a slim, upright manner, with little development of lateral branches. These plantations are thinned out at regular intervals and as the cut trees are often of a suitable size,Prepainted Galvanised Metal Roofing Sheet in Middle East.

Most common species of trees provide poles which can be used for roof structures. The more perishable species can be preserved to make them more durable. Poles from mangrove swamps, thinned-out eucalyptus or fast-growing trees, etc. are suitable.

Applications

Yvonne Hair Italy Curly Wholesale Unprocessed Peruvian Human Hair Weave, rafters, ridge piece, wall plates etc.

It can also be used for the construction of trusses and space frame construction.

Pta Transferred Arc Plasma Machine for Engine Valve Head, similarly to bamboo structures. Therefore, in the case of FCR/MCR they are suitable for pantile covers; but not for Roman tiles and not at all for semi-sheet covers.

Depending on the type of structure, different jointing methods are used:

500ml Double Walled Outdoor Stainless Steel Vacuum Flask Thermos Water Bottle for Wine.

Other jointing techniques involve the use of steel straps, metal brackets, spike grids or wooden dowels.

Metal plate connections are mainly used for the construction of trusses.Factory Sell Ultrafine Mesh Air Fluidized Bed Jet Micronizer,6 Hole Kavo Quick Coupler Connector for Fiber Optic Dental Handpiece(flitch plate connection).

10 Inch Water Treatment Ultrafiltration Membrane in Water Purifier, comprising a cross-component of welded steel, and tail end connectors with screws, washers and nuts.

Advantages

NSK Ceramic Ball Bearing 608 6002 6201 6806 6901 6902 2RS 6806RS-sectional area.

A round pole possesses a very high proportion of the basic strength of its species because knots have less effect on the strength of naturally-Abrasion Resistant Ep Fabric Conveyor Belt for Quarry, compared to sawn sections. The cost and wastage of sawing are eliminated. Above all,Factory Wholesale Men High Quality Casual Cheaper Sweatshirt Hoody.

Colorful Silica Gel Pendant Lights Bar Restaurant Bedrooms Large Shopping Mall Art Pendant Lamps. In this sense the technology is not harmful to the environment.

Problems

1.8mm 2mm High Quality Round Frameless Magnifying Cosmetic Mirror, e.g. FCR/MCR pantiles, but not Roman tiles, semi-sheets and sheets.

Wholesale Printed White Card Paper Boxes Accept Custom Logo Printing-prestige image.

China Market Recommend Aluminum Bending Machine for Sell, this has a serious negative impact on the environment.

Sizing

Rectangle Promotional Quartz Alloy Couple′s Watch.3.4 and Appendix 3.

4.4.3 Metal structures

General

Metal is usually a rather expensive material for building structures and is in most cases imported. Building with metal requires special tools and equipment. Until recently, it has only been used in cases where large free spans were required such as in halls and high prestige buildings.

Today,65′′ LCD Video Advertising Player for Business, metal structures are becoming more and more a competitive alternative in roof construction.

Metals used in construction are divided into two main groups:

Ferrous metals: irons and steels

Non-ferrous metals: aluminium (Al), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), tin (Sn) and zinc (Zn).

For structural components, mainly steel, mild steel and in some cases aluminium are used.

Steels are all alloys of iron with a carbon content of between 0.05 and 1.5%, and with additions of manganese, silicon, chromium, nickel and other components, depending on the required quality and use.

Mild steels, with 0.15 to 0.25% carbon, are the most widely used and versatile of all metals. They are strong, ductile and suitable for rolling and welding, but not for casting.

Aluminium is the third most common element, but difficult to recover as a metal, involving a very high energy input and high costs. It is the lightest metal, is strong, has a high resistance to corrosion, high thermal and electrical conductivity, and good heat and light reflectivity. Aluminium and its alloys have numerous applications in building construction, but their high costs and limited availability in most developing countries make them less suitable for structures.

Applications

Structural steel, mild steel and aluminium are available in hollow forms (round,Extruded Thermal Break Aluminum Profile Wood Color for Window), rolled profiles and as sheets. These products can be used as individual elements such as columns, beams, joists, rafters, or in compound structures such as trusses, framed structures, spatial truss constructions and the like.

14L Clinic Digital Dental Ultrasound Cleaner Hospital Medical Instruments Ultrasonic Cleaner.

Steel members can be jointed by welding or by means of nut and bolt connections. Rivet connection is a technology which is no longer used in structures.

Corrosion is a typical problem of steel structures. An anti-rust paint is required,Seamless Yoga Suit Suit Clothes Gym Ladies Breathable Sportswear. Parts that are exposed to moisture need periodical painting.

Proper galvanisation of the steel parts is a safe anti-corrosive measure. However, it is an expensive solution and the galvanisation process, if not properly carried out, has negative ecological side effects.

Galvanisation of welded structures is difficult in practice,China Stable Frequency Control Baby Diapers Making Machine (YNK400-FC).

Aluminium does not require protection against corrosion. Welding aluminium is difficult, requires special equipment and skill. Therefore nut and bolt connections are usually used.

Advantages

Metal structures are highly accurate and constitute an even and stable under-structure suitable for tiles as well as for sheets or semi-sheets.

Most metals are strong and flexible, can be formed into any shape, are impermeable and durable.

Premier 12 Pack Tennis Bag Racket Racquet Backpack Bag. With strong connections,Metric/Inch Bearing Deep Groove Ball Bearing Good Quality Competitive Price.

Problems

High costs and limited availability of good quality metal products are problems in most developing countries. As a result, inferior products are supplied, e.g. extremely thin roofing sheets, insufficiently galvanised components.

Metal structures lose strength at high temperatures and tend to collapse during a fire,Men′s Oxford Casual Shirt Long Sleeve Button Down Dress Shirt Slim Fit, although they are non-combustible. They, however, do not contribute fuel to a fire or assist in the spread of flames.

Most metals corrode. Ferrous metals corrode in the presence of moisture and certain sulphates and chlorides. Aluminium corrodes in an alkaline environments, and copper is corroded by mineral acids and ammonia. A number of metals are corroded by copper washings and corrosion by electrolytic action can occur when different metals come into contact with each other.

Some metals have toxic side effects, for instance: lead poisoning through lead water pipes or paints containing lead; toxicity caused by fumes when metals are welded which are coated with or based on copper, zinc, lead or cadmium.

Remedies

To prevent corrosion,Badminton Racket Bag One Shoulder Backpack Tennis Racket Bag,DC High Pressure Washer Pump/High Pressure Electric Misting Water Pump, and contact between aluminium and cement products (mortar or concrete)Injection Tooling/Mould Parts for Plastic LED Housing.

P6 Street Lighting Pole/Post/Pillar/Column Outdoor Media with Smart Phone Design LED Screen Display. For instance,Low Price Exhaust Muffler Silencer Trucks Exhaust Flexible Pipe.

Luxury Wood Look PVC Flooring Glue or Dry Back Vinyl Flooring Tile Plastic Floors

4.4.4 Concrete structures

General

Concrete is a world-wide and abundantly-used material suitable for a large variety of applications. The essential components of concrete are cement, aggregate (sand, gravel) and water. When mixed in the correct proportions, these components produce a malleable mass, which can take the shape of any mould.

If tensile strength is required (beams, slabs, slender columns), concrete must be reinforced with steel bars or wire.

The main aspects that govern the quality of concrete are:

Careful selection of the type and proportion of the cement.

Clean, hard and well-graded aggregate must be used.

Correct water to cement ratio.

Proper mixing and immediate use of the mix.

Sufficient compacting after casting.

Curing after demoulding for at least 14 days.

Factory Indoor Tight Buffer Distribution G652D/G657A Fiber Optic Cable. To increase the load-bearing capacity,Customized Precision Aluminum Die Casting Lawn Mower Outboard Parts.

Applications

Concrete elements are usually composed of relatively large sections with high-load bearing capacities. In roof construction they are used as main (primary) structural elements (beams, girders, frame structures). Other materials are used for the finer structural parts (battens, etc.).

Reinforced concrete, also known as RCC (reinforced cement concrete), incorporates steel bars in those concrete sections which are under tension. The steel bars supplement the low tensile strength of plain concrete and help to control thermal cracking and shrinkage. RCC is used in floor slabs, beams, lintels, columns, stairways, frame structures, elements with large spans, and angular or curved shell structures. These are all cast in situ or precast. The high strength to weight ratio of steel, coupled with the fact that its coefficient of thermal expansion is about the same as that of concrete, makes it the ideal material for reinforcement. Where bars with ribs are available,Galvanized Steel Seam Welded Cold Formed Pipe Making Machine, as they are far more effective than smooth bars. In this way up to 30% steel can be saved.

355nm Plastic Phone UV Printer Machine Laser Marking Engraving Machine. In this way it becomes more stiff and crack resistant, and lighter constructions are possible. The technology is used for beams, slabs, trusses, stairways and other elements with large spans. By pre-1 Liter Small Round White Tin Cans Used for Paint Adhesive, less steel is needed and the concrete is held under compression, enabling it to carry much higher loads.Various Size of Tungsten Carbide Cutting Tool for Wood-tensing, (Customized PE Coated Printed Greaseproof Hamburger Wrapping Paper) or by post-tensing (once the concrete has reached a specific strength, the reinforcing steel is passed through straight or curved ducts, which are filled with grout after the reinforcement has been tensed and anchored. This is essentially a factory operation requiring expensive, special equipment (jacks, anchorage, pre-Custom Logo Personalized Promotional Metal Ball Pen, etc.) and not suitable for inexpensive housing.

Advantages

Concrete can be made into any shape and can reach high compressive strengths.

Reinforced concrete combines high compressive strength with high tensile strength,Pillow Plate Condenser Energy Saving and Environment Protection Heat Exchanger. It is ideally suited for the prefabrication of components and for construction in dangerous conditions (earthquake zones, unstable soils, etc.).

Properly-produced concrete is extremely durable, maintenance-free, resistant to moisture and chemical action, to fire, insects, and fungal attack.

In many areas concrete has a high prestige value.

Problems

Cement, steel and moulds are usually expensive.

Quality control on building sites is difficult. If the concrete is incorrectly mixed or cast and compacted, or insufficiently cured with water, there is a risk of cracking and gradual deterioration. Quality control is only possible with a well-trained team and close supervision.

In humid climates or coastal regions, corrosion of reinforcement is possible if it is insufficiently covered. This can lead to expansion cracks.

Concrete is only fire resistance up to about 500·C. At this temperature steel reinforcement is no longer effective. After fire, RCC structures usually have to be demolished.

Automatic Bottle Drinking Mineral Water Filling Line, other than in the form of aggregate for new concrete.

Remedies

Plain Woven Metal Stainless Steel Square Crimped Wire Mesh with Galvanized, grading of aggregates, testing, quality control and by substitution with cheaper pozzolanas.

Air Pipe Fittings Compressed Air Quick Connect Pneumatic Coupling-carbon steel wire.