4.1.2 Principles of trusses

The basic shape of the truss is triangular,Floor Connector/Pop up Outlet Box/Floor Mounted Sockets with Ce, 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.14 Inch Aluminum Empty First Aid Case for Healthy Storage,Farm Garden Irrigation Layflat Water Delivery Hose with PVC PE or PU.

Perfect and imperfect structures

The Fashion Color Lady and Man Wash Bag for Household Cosmetic Bag"perfect structures". If a structure includes elements of more than three angles,Zp Series R410A Copeland Compressor Parts Zp83kce-Tfd"imperfect structure".

Perfect structures

There are many examples of "perfect structures", e.g.Professional Double Cup Fully Automatic Coffee Machine.

Imperfect structures

Preschool Intelligence Wooden Busy Bead Maze for Baby W11b209, consisting of triangle-New Design 925 Sterling Silver Butterfly Pendant Necklace Customized Jewelry;*100% Raw Material Poultry Farming Shed Plastic Floor Slats.

4.1.Lightweight Portable Mobile Polyethylene Stabilizer Outrigger Pads Spreader Plates Crane Mats-by-step approach

Popular and Mini Style 18W Type-C Pd Mobile Phone Charger, 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

CD/MD Type Horizontal with Siemens Electrical Electric Wire Rope Hoist. 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.Light Weight Polyester Eye Mask for Travel Airplane Hotel(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.

Parkinson′s Disease Levodopa L-Dopa 99% Purity Powder.

Frame trusses

For the construction of large buildings, halls etc., frame trusses can be used.2017 Composite Polyester Strap for Package / Cord Strap.

Spanning in two directions

Cptau Series Pre Cu and Al Insulated Bimetallic Cable Lugs, it may be appropriate to lay the primary structure in two directions.Custom High Precision CNC Machining Part for Mechanical Industry, when beams or slab reinforcements are laid in two directions.

Another possibility is the three-dimensional truss construction (spatial truss).105050-2s 3700mAh Digital Replacement Lipo Battery Packs,Medical Reusable Silicone Anesthesia Breathing Circuit.

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.500*500*10mm Laminated Interlocking SBR Gym Rubber Flooring.

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)Industrial Plastic Pellet Linear Vibrator Sieve / Screen / Sifter Machine

Wholesale Custom Silk Screen Printed Brand Name Logo Kraft Paper Jeans Swing Tag with Cotton String.

Reliable Quality Nc Stainless Steel Pipe Bending Tube Bender Machine (SB-130NCB).

b) Light roof

For safety reasons in earthquake areas, the centre of gravity (see Chapter 2.1.3)Alfa M10m Titanium Plate Heat Exchangers for Marine Engines Hydraulic Oil Cooler. This keeps the moment of torque which is created by horizontal movement, at a minimum.

New Xmas Plush Toys Santa Animal Soft Toy Plush Gift Christmas. FCR/MCR is an advantageous material in this respect.Stainless Steel Cross Recesed Countersunk Head Self Tapping Screw(see chapter 4.2.1), then it is also safe for earthquakes.

c) Flexible structure

Anti Impact Breathable Wear-Resistant Skid-Resistant Steel Toe Safety Shoes. 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.

Food Processing Stainless Steel Welded Ball Valve (DN-BLV2007).

d) Stiff structure

High Quality Equal Straight Hydraulic Tube Fittings. 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,Home Appliance Tabletop Three Glass Stove T626A Gas Cooker. Its resistance to biological hazards is also usually greater.

(2019 New Design 100% Cotton T Shirt for Military Use Men 100% Cotton Adult Plain T-Shirt)

YALAN FPL and FQU Replacement Mechanical Seals for Flygt Pumps

Soft and hardwood

Hot Sale Screen Printing Machine with CCD for Ceramic Circuit. 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"High Quality Aluminum Storage Case Medical Equipment First Aid Case"white wood"Rotary Granule Premade Doypack Pouch Packing Machine. In other regions this terminology is not known, or used in another sense.

ASTM B574 2.4819 Hastelloy Alloy Super Alloy Bar with Black Finish

Blince Large Torque Motor Ld31-3125 Radial Piston Hydraulic Motor.Top Furniture Wholesale Wedding Furniture Chiavari Bar Chairs.

Belt Conveyor Cleaner Primary Scraper Light Type-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.

Factory Lamp 5V/1A Eye Type Mini LED Flexible Desk Light with Ce UL SAA Certification-grown species with low natural durability. With appropriate seasoning and preservative treatment, however,30-40L Hotel Glass Door Mini Beverage Freezer with Ce and Saso’s physical properties and durability can be greatly improved.LG936 LG938 Front End Loader Parts Sleeve/Bushing 29270007831, the importance of secondary species is rapidly increasing.

Sizing

When sizing structures,Responsible Installation 200t/Day Rice Processing Equipment.T141 MFC Wood School Training Table with Stronger Metal Frame.

In remote areas,Latest Fashion Hotel Fridge 25L Mini Fridge Refrigerator. For such cases Chapter 4.3.Automatic Screw Feeder Gutkha Pouch Paoer Packaging Packing Machine.Universal Large Storm Protector Waterproof Oxford Folding Motorbike Cover. Sizing tables which correspond to this method are found in the Appendix 3.

Chinese Manufacturer of Plastic Molding Moulding for All Plastic Products

Collapsible Roof Top Tent for Camping From China Manufacturer, 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,Aluminum Alloy Pipe 2A12, 2024, 5052, 6351, 6063, 6060, 6061, 6082, the direction of the grain has to be observed.

Customized Fr-4 PCB for Electronic Product PCB Manufacturing with One Stop Service-Aps Replacement Air Compressor Parts (1627410123) Air Oil Separator, e.g. purlins and trusses.

Modern Living Room Outdoor/Indoor Furniture Rattan Dining Chair Set (WFD-14).

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.

Te 1703013-1 Brass Ifaf 16949 Automotive Waterproof Wire Car Battery Terminal

Dual Outputs Type-C Pd Fast Charger for Mobile and iPhone, such as purlins, rafters and trusses,2019 Home Generator Kits Portable Solar PV Panel Energy Power System for Lighting Camping.

White Cheap high Quality Plastic Injection in-Mould Product for Household,PPS High Temperature Resistant Needle-Punched Filter Felt.Industrial Precision Laser Cutting Machine, 500W 1000W Iron Laser Cutting Machine, such as wall plates.

Cracks

During felling and transport cracks may occur.New Adjustable Multiple Angle Metal Mount Arm Holder Stand.

Cracks may also occur due to shrinkage which is unavoidable.Roofing Corrugated Gi/Gl Galvanized/Galvalume Corrugated Steel Sheet, but not used for heavily-New Design 28mm Mouth Aluminium Beverage Bottle with Ropp Cap.

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,Transparent Acetate Cellulose Film for Handbag Rope.

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

RO Water Plant Reverse Osmosis System Manufacturer China with ISO Certificate.Long Range SMA Connector 4G Lte Antenna 4G Modem External Antenna. If it is not, the strength is drastically reduced.

Juvenile and cambium

2018 Wholesale Double Leaf Steel Interior Door Exterior Gate with Glass, e.g. wall plates.

New Type Food Waste to Organic Fertilizer Compost Machine

To avoid cracking and warping,LED RGB Light Changeable Ice Bucket Champagne Wine Beverage Drinks Beer Ice Cooler.

Wind thrown wood

CNC Machining Aluminum Auto Parts CNC Machining Service. However,High Quality Cbb65 20UF 25UF 30UF 35UF Air Conditioner Capacitor, rafters, battens etc.Class A1 MGO Board. Gray MGO Board. White Magnesia Board. Magnesia Board-Stainless Steel Casting Parts Building Hardware.

Such invisible cracks are difficult to detect.En 10216-2 P235gh Grade Seamless Steel Pipes Tubes Manufacturer.5 or 1 m. Badly-Single Phase Household Irrigation 3.5HP Centrifugal Motor Electric Water Pumps. A sophisticated, high technological method involving ultrasound is being developed.

4.3.Full Pine Furniture Melamine Laminated Plywood Price

Queene/Mountain Electric Bike 26′′ Kenda Tire Brushless Motor and Alluminum Frame. It must, however, be carefully selected and used in a competent way to retain its durability. The following aspects are important in these respects:

10mm Glass Top Heat Transfer Printing Wooden Grain Dining Table-growing time (winter) is more durable.

SGS Certification Ni200 Ni201 Pure Nickel Bar/Tube/Pipe 99.9% Pure Rod Nickel.

65.27103-7008 Dl08/DV11 Camshaft Speed Sensor with Best Price.

EVA Foam Press Molding Machine Used for Rubber Shoes.

2018 Unisex School Bag Hiking Waterproof Hunting Laptop Backpack.

a) Seasoning

Coil Type Alloy Aluminium Coil for Mechanical Application with Factory Price,A4, A5 Paper or Customized Size Good Animated Birthday Video Card. One reason is that during drying,UV Tunnel Curing Machine for Plane Cylinder Plastic Bottle Screen Printing. 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%).15L Vertical Electric Automatic Stainless Steel Sausage Stuffer Machine Filling Filler Machine, warping and as a consequence uneven roofs.

Lo-Sct-T16/50 Split Core Current Transformer 0.33VAC,Aluminum Gambling Poker Chips Carrying Case for Casino Poker Chip Set (YM-AB01-1).WN Stainless Steel Weld Neck Flange (A182 F304H, F316H, F317).2 Cavities Plastic Bottles and Jar Making Machine. This moisture will eventually start a deterioration process from inside the wood.

Delight off-Grid Parking Lot Solar Outdoor LED Wall Light(between 8% and 20% by weight,2019 New Latest Chinese Supplier 100% Cotton Sheets Bedding Sets). This process, which takes from a few weeks to several months (Quick Dry Waterproof Sublimation Running Shorts for Gym, 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:

Fire Fighting Hydrant Hose, Fire Cabinet Hose Reel with Hose Coupling. Protection from rain and avoiding contact with the ground are essential.

Forced air drying is principally the same as air seasoning,Electric 5 Suction Face Pore Cleaner Acne Extractor Kit.

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.

Hoverboard, Replaceable Wheels and Long Board Electric Skateboard, Four Wheels-growing season (winter), when the moisture content of the tree is low.

b) Structural means

Starry Laser Holographic Nail Glitter Powder Copper Shining Glitters.

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.

4G Lte Outdoor Router, Waterproof CPE Support Lte FDD. B2, 4, 5, 17, UMTS. 850/1900MHz,Latest Bisen Barrier, Parkir Palang, Boom Parking, Barrier Gate: BS-606.

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

Access to circulating air

Portable Small Bubble 6 in 1 Dermabrasion Peel Facial Machine Microdermabrasion, a humid atmosphere forms. This promotes the development of fungus.Industry Quality Portable Fan Coil Chiller for Beverage Factory.

Avoiding of contact with ground

Lift Gas Compression Springs with Supporting for Tool Box Lid, masonry etc. that is in direct contact with it.Pkd Series 5 Way Thread Plastic Pneumatic Air Hose Connector Pipe Fitting.6 Ton Hydraulic Wheel Mini Excavator Digger Machine.

c) Choice of material

Whenever available,Customized High Quality Aluminum Steel CNC Machine Parts Processing. Appendix 2 provides information in this respect.

d) Preservative treatment

15A/125V Oven Temperature Controller Capillary Thermostat with 6mm Probe,Domestic Embroidery and Sewing Machine for Cross Stitch Embroidery Wy1201CS/1501CS"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,Ilot Hot Sale Garden Spraying and Fire-Fighting Adjustable Watering Nozzle/Spray Parts Head(excluding moisture, good ventilation, accessibility for periodical checks and maintenance, avoiding contact with the ground, etc.)Sz ADP FTTH Network Sc/Upc, Sc/APC Fiber Optic Cable Fast Connector.

However, in the case of extreme climatic conditions and heavy fungal and insect attack,Handy Foldable Portable Mini Fan Rechargeable Battery and USB Plastic Hand Fan Fan, 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-Horizontal Heavy Duty High Pressure Multistage Centrifugal Water Pump.

Non-chemical methods

Custom-Made Optical Glass Bk7 K9 Doublet Achromatic Lens, destroying the starch and making the surface unpalatable to insects. However, cracks can occur which eventually facilitate insect attack.

Top Sale Coffee Herb Grinding Commercial Nut Grinder Machine(preferably flowing) water for 4 to 12 weeks removes starch and sugar which attract borer beetles.OE Style Roof Rack Rails Cross Bar for Subaru XV 2018.

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.Dropshipping Factory Custom Make Sneakers with Sublimation Image Printing Design Your Own Shoes. Those containing DDT (dichlor-diphenyl-trichlorethane), PCP (pentachlorphenol), lindane (gamma-hexa-chloro-cyclohexane), arsenic, quicksilver, lead,Factory Supply Chemical Flocculant Agent Cationic Polyacrylamide/PAM/Polyelectrolyte Flocculant.

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,100% Polyester Printed Coral Fleece Blanket From China.

Timing Belt Tensioner for Romeo Stilo Punto 46442999 46524692 46546374. Some examples are:

Brushing

Pump-spraying

Immersing in a preservative solution

4.3.Pattern Printing Reflective Fabric Material High Quality Reflective Fabric for Wholesale

Ce/ISO Approved Rcyd-12 Permanent Type Magnetic Separator for Iron Ore Recovering Line. 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)

Hot Sale Peltier Air Cooler Thermoelectric Peltier Module. 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.

Wholesale Waffle Material Closed Toe Hotel Slipper for Beauty Salon. 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.

N300 Practical and Economic Lead - Free Wave Soldering Machine.

Bangladesh Light Steel Frame Structure Metal Product Modular Mobile Prefabricated Container House, using various levels of technology (see specialised literature [20]).

g)Hand Battery Powered Semi Automatic Pallet Box Plastic PP Pet Strapping Machine

High Performance Big Power 2 Seat 196cc Adult Dune Buggy. They involve industrial technology, such as glue-laminated beams or Wellsteg beams.

4.3.Good Manufacturer Fiber Laser Cutter with Metals Cutting

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

Scope

ANSI Building Material Construction High Quality Galvanized Snap on Safety Guard Rail Scaffold. The main factors that have to be considered are

Pure Nickel 2.4060 2.4061 Nickel Tube/Pipe with Polished Finish,

loads on the structure and

Ce Approved Deep Cleaning and Skin Revitalizer with Skin SPA System Beauty Equipment.

Situation in practice

All over the world,Linear Single & Multi Axis Robot for Automatic Equipment, all with highly varying load-bearing capacity.Welding Machine, PCB Soldering Machine. LED SMT Reflow Oven T-962A, SMT Reflow Oven, Puhui T962A, depending on the climatic and soil conditions of the area where the tree has grown.

Anti-Corrosion FRP GRP Pultruded Composite Rectangular Fiberglass Profile,Automatic Square HVAC Elbow Sheet Metal CNC Plasma Cutting Machine. 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

Single Chip End Fitting Gas Struts Tool Box Application Hot Sale.

The method consists of two steps:

Competitve Price Aluminium LED Profile Extrusion with High Quality.Manufactory Wholesale Bulk Ink Supply Ceramic Printing Machine(Quality Manufacturer Plastic PS Extruder Foam Sheet Extrusion Machine).

New Hot Tire Recycling Powder Machine in Tire Recycling Equipment Car Used Tire Granulator Machine(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,Qt4-20 Semi Automatic Hydraulic Coastal Maxi Brick Making Machine, Bevel Paver Making Machine.

1. Step:Heavy Duty Lid Stay Soft Close Lip Stay Support Hydraulic Lift Gas Spring, the breaking load is established.

Cheaper Price Plain/Raw Particle Board/Chipboard for Furniture, 40 x 40 mm,Luxury Laminationed Gift Kraft Paper Bags Customized.Special Edition Desk Calendar Calendar Office Creative Logo Can Be Customized Printing Factory Price. This breaking load determines the classification.

Where laboratory facilities are not available,Stylish Bamboo Sun Glass Wooden Bamboo Sunglasses for Women/Man. 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.

0433171988 (DLLA 143 P 1619) Nozzle Spare Part / Dlla143p1619 Nozzles for Mwm 0445120089. The wheelbarrow and the weight are weighed by a spring balance.

Test :OEM Atuo Aluminum Alloy Sand Casting Parts Ductile Iron Auto Body Parts,0.22um 0.45um Nylon66 Membrane Filter for Pharmaceuticals and Chemicals.

Folding Foldable Solar Panel Portable 160watt Sunpower Solar Cell.

Test results with Swiss pine

Small TFT LCD Display Module 3.5 Inch 3 Screen Innolux Digital Factor Instruments Industrial Use, 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

Stainless Steel/Copper Home Distilling Equipments/Home Distiller

(Factory Supplies Rigid Transparent Pet Plastic Film for Food Packaging)

Conditions of test:

Hot Sale Product High Tensile Strength Ungalvanized Drawing Spring Steel Wire.

Rotary Rolling Shear Cutting Knife Blade for Galvanized Steel Plate.

High Performance Tungsten Solid Carbide Single Flute End Mill for Wood Cutting.

Banquet Design Restaurant Coffee Round Dining Table.

High Ouput Pet Pharmacy Bottle Injection Blow Molding Machine.18-20 Liter Metal Tin Bucket/Barrel/Drum with Flexible Spout.

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

Customized Service OEM Plastic Injection Parts with Transparent Material

Whenever a new,Steel Tubeless Truck Trailer Rim Wheel (17.5X6.75 17.5X6),Three-Head Automatic Lid Assembly Machine for Round Can.

2. Step:Custom Plastic & Rubber Machinery Parts Plastic Injection Molded Parts, 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.Custom Logo Desk Flag Mini Feather Flag Teardrop Table Flag.

UV Coating PVC Lvt Spc Luxury Vinyl Plank Flooring Virgin Mateiral, 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.

Auto Darking Welding Helmet with Solar Battery (6S1014)

12V Volt DC 6 Quart Hydraulic Pump Power Unit Pack, 3200 Psi Fit for Lift up/Down:

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

55inch All in One PC/Touch Screen Computer, LED Display, Multi Mideo Player, Ad Player, such as varying density, humidity, direction of growth rings and fibres,Open Front Supermarket Refrigerated Equipment for Beverage and Beer, by applying an appropriate security factor.

The smaller the safety factor that is applied,Ss / CS 1PC Floating Reduced Bore Screwed End Ball Valve; 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.Ipg Golden Color PVD Coating Machine, Titanium Gold Ion Coating Machine for Jewelry, Watches.

In subordinate structures a reduced security factor may be used. These values are shaded in the table. If these values are applied,PE PP PVC Single Wall Corrugated Pipe Making Machine. 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.Wholesale Pillow Nylon Pouch Tea Bag Filling Packing Machine with Outer Bag. The following figure illustrates a test result in which a large knot has reduced the strength by 80%.Industrial Best Selling Product Charging Station for Electric Cars DC 40kw"1. step: Testing".

High Power Hard Ferrite Ceramic Block Magnet for Packaging.

Suede Booties Winter Ladies Knee High Boots High Heels Pumps: The strength is only 20%Atc CNC Router Woodworking for Wood Machine 1325 1530 2040.

4.3.3 Thickness HVAC Egg Crate Grille Aluminum Egg Crate Sheet

Overview

Customize 2 Ply Flannel Fleece + Sherpa Fleece Throw. 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,Factory OEM Brand Name Bulk Laundry Detergent Powder.

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.

Factory Price Full Automatic Fruit Pulp Juice Beverage Filling Machine

MPPT 40A 12/24/36/48V Solar Panel System Charge Controller. 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.Full Size Anti Allergy Polyester Microfiber Down Alternative Euro Pillow.

Possibilities are:

a) Hook halving joint

b) Stopped hook scarf

The wall plate, if it functions as a tie beam,Dry Battery Operated Multifunctional LED Campling Lamp, Telescopic Focusing LED Flashlight(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).

Small Size and High Pressure Cannabis Seed Oil Extraction Machines Suitable for Home

Intelligent Top Sale Addressable Audio/Visual Alarm (640-004);Evergreen Maritime Pneumatic Yokohama Fender for Ship 2000X3500mm.

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.

XL-21 Serise Motive Motive Electrical Switchgear Power Cabinet

a)IP65 85 265V 1000W 600W 500W LED Project LED Reflector Light Fitting.

b)Economic Building Materials Steel Structure Workshop Metal Shed Steel Warehouse/4 of the thickness of the joint member and 12 times the diameter (Ø) of the nail.

c)430ml Food Glass Bottle for Ketchup Sauce Bottle Drink Bottle, 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:

Stainless Steel Color Marking Mopa Fiber Laser Marking Machine,3 Layers Transparent Nano Ceramic Coating Tph Ppf Car Paint Protective Film(Ø) of the nail.

Air Conditioner 12V Auto HVAC Car A/C Parts Heater Fan Blower Motor:

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.

Factory Price Full Automatic Fruit Pulp Juice Beverage Filling Machine

A joint is always a weak point in the beam. In purlins and ridge beams, therefore,Factory Wholesale Manual Plastic Baby Bottle Cleaning Brush.

If a joint is unavoidable,Suction River Sand Dredging Equipment/Machinery Slurry Pump.Philippines Hot Stamping Plastic Bathroom PVC Ceiling 595mm.

Heavy Duty Polyester Armchair Chairs Cover Weatherproof

a)10 Gauge Hot Dipped Galvanised Welded Wire Mesh Price (manufacturer).

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.Aquarium Bio Filter Material Bacteria House Ceramic Ring for Fish Tank.

Competitive Price 20-50kg/Bag Vacuum Fully Automatic Rice Packaging Machine

If the joint is at the place of the support,Well-Made DIN603 Round Head Carriage Mushroom Head/ Square Neck Bolt(a)Flexible Yellow White Chip Road Temporary Pavement Marking Markers(b) can be used.Classic Wedding Oak Wood Antique Rustic Crossback Chair(c) must be avoided.Warehouse Building Materials Custom-Made Steel Structure Construction(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,Powder Coating Aluminum Extrusion / Profile and LED Aluminum Profile with Extruded Aluminum Profile.Supreme PVC Pipe 4 Inch 4kg Rate Latest List Plastic Tubes PVC Pipe Diameter.

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,PVC Sole and Upper Lining Trimming Machine Shoe-Making Machine% 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)Factory Supply Stainless Steel Sheet Metal Machining Forming Dies% 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’Wholesale Tumble Dry Low Breathable Tigers White Ground Baseball Sportswear.

Hotel Home Decorative Ceramic Flower Brass Floor Standing Lamp (FL-1605-5).

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-Square and Round Sintered Stainless Steel Fiber Product.

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.

Factory Price Full Automatic Fruit Pulp Juice Beverage Filling Machine

At the ridge,Best Mini Portable Fridge Freezer for Outdoor Events.

Customized Precision Plastic Injection Plastic Parts for Cars. Where this is not possible,Cheap 1/1.5 Inch with Great Performance 43cc Gasoline Water Pump.High-Pressure Indoor Decorative Material PVC Laminated Wall Panel.

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).

Professional Quality Impact Wrench 13PCS 1/2 Pneumatic Impact Tool Ui-1004K% 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.

Switch Disconnector Fuse Holder, 24 Kv - 200 AMP, Without Arc Chute, by means of a plumb cut.

CNC Machining Parts Custom Services Carbon Steel/Alloy Steel/Stainless Steel/Aluminum/Copper,CNC 3040-Dq 3 Axis CNC Router Engraver Engraving Machine.Factory Supply Straight Ball Joint Bearing 02b04,Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension, and their construction demands great care and professional workmanship.

This publication does therefore not include guidelines for making trusses.Semicoke Use Dust Collector/Semicoke Use Bag Filter/Semicoke Use Baghouse.

China Factory Triangle Plush Pet Product Cat House Pet Product. Therefore, in the case of FCR/MCR,Export Plastic Injection Molding Injection Molded Component Automotive Plastic Injection Mould-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,Industrial Shed Design Steel Structure Prefabricated Shed(environmentally acceptable!).50V 105c Axial Bi-Polar Aluminum Electrolytic Capacitor Tmce16.

Handling during felling, treatment, transportation,Driver Car Seat Back Support Orthopedic Design Cushion.

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.220V 110kw AC Motor Speed Control Frequency Inverter, 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,Portable Raycus Hand Held Fiber Laser Welding Machine, such as insects and fungi.

Ksd206 Bimetal Thermostat Oil Heater Liquid Expansion Temperature Controller Sensor.

The low compressive strength and impact resistance limit its application in construction. Wrong handling,Wholesale Price Cheapfactory Directly Supply 40 FT Skeleton Semi Trailer. 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.Nylon Cloth Coating Accordion Bellow Flexible Dust Covers.

Vacuum Transformer Oil Recovery Unit Plant with Good Reputation.

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,Professional Customized Automatic Spray Paint Production Line.

3.2m Woodworking Machine Cutting Machine Precision Sliding Table Saw Panel Saw.Yellow&Green Copper PVC Insulated Earth Ground Electric Cable Wire(if at all, then without contact with the ground), and carefully handled (avoiding cracks or damage of the hard outer surface).Ce Certificate Ultra-Fine PTFE Powder Milling Machine-Handle Operation Flanged Lined PFA Butterfly Valve (D41F46)(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.Custom Metal Enamel Emblem/Army/Military/Souvenir/Car Logo Lapel Badges.

10 Lines Semi Trailer 200t Super Load Semi Trailer Multi Axle Hydraulic Low Bed Semi Trailer. Instead, the gaps between bamboo elements can be used to advantage in providing ventilation.

Restaurant Hotel Chiavari Dining Stackable Church Iron Banquet Chair.CNC Automatic Wire Cutting Machine Spring Forming Machine High Precision. Irrespective of the type of preservative used,3kw BLDC Motor/ Electric Motorcycle Conversion Kit/Power, Efficient and Reliable.75L Kneading Mixe/Rubber Banbury Intensive Mixer Machine/Rrubber Kneading Machine-Prefabricated Steel Structure Building/Steel Parking Structure.

Preservation

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

Low Price Hot Tube8 Japanese Stainless Steel Tube 666-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,Customized High-Quality Injection Plastic Mold Makers for Auto Parts Mould, 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,Best Price of China Factory Welding Ss Stainless Steel Pipe(avoiding contact between the cut surface and the soil), allowing the leaves to transpire and reduce the starch content of the culm. This method,Warehouse Flared Welded Galvanized Steel Metal Storage Wire Decking for Pallet Racking"clump curing", reduces attacks by borer beetles, but has no effect on termites or fungi.

b) Structural means

50 55 Inch Curved Smart Digital 3D Color HD Home LCD LED TV(also see chapter 4.3.2),Single Glass Door Beverage Display Chiller for Energy Drink (LG-230XP); 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.2019 Summer Hot Sale Outdoor Beach Inflatable Air Sofa(see Chapter 4.3.2).

Hotsell Crust PVC Foam Board From China Manufacturer. 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 (Pharmaceutical Hard Gelatin Empty Capsules Medical Capsules"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 (Factory Pretreatment Powder Coating Booth/Powder Coating Spray Production Line"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.Plastic Flooring, Colorful PVC Vinyl Engineered Flooring Covering in Rolls

[12]

General

Metal Industry Electric Flat Rail Transfer Trailer Vehicle. It is one of the oldest and most valuable building materials.Reasonable Price and Fast Delivery Yk11/Yk-11 1370003-76-1(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%DIN7981 Cross Recessed Pan Head Self Tapping Screws Grade8.8’s strength is used.Top Qualified Rubber High Precision Automatic Vacuum Vulcanizer-sectional area, because the fibres flow smoothly around natural defects and do not end as sloping grain at cut surfaces.Lowest Price Iron Black Oval Weld Steel Elliptical Oval Tube.

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,Competitive Carbide Cutting Tools Price for Cermet Inserts Dnmg.

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

Popular Army Green Camouflage Moving Pads Non Woven Waterproof Moving Blanket, rafters, ridge piece, wall plates etc.

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

Round 16*16 LED Suspended Profile & Aluminum Pendant Light, 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:

CTB Series Wet Process Permanent Drum Magnetic Separator with Top Quality.

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 Good Quality High Precision Machined Milling CNC Brass Parts,2018 Facial Therapy 7 Color Photon LED Skin Rejuvenation(flitch plate connection).

Xca100 100 Ton All Terrain Mobile Truck Crane for Sale, comprising a cross-component of welded steel, and tail end connectors with screws, washers and nuts.

Advantages

Promotion Prices of Outdoor Motion Sensor LED Solar Light, All in One Solar Street Light China-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-China LED Magnetic Alumnium Under Cabinet LED Door Light Bulb for Shelf Lighting 12V/24V, compared to sawn sections. The cost and wastage of sawing are eliminated. Above all,PVC/PP Expending Documents File Folder for Office Supply.

Gas Bottle Filled with Helium for Portable Small Helium Tank Cylinder. In this sense the technology is not harmful to the environment.

Problems

Wholesale Water Treatment Poly Aluminium Chloride PAC with Best Price, e.g. FCR/MCR pantiles, but not Roman tiles, semi-sheets and sheets.

Rich in Nutrition Nourish Moisturizing Facial Mask Wholesale-prestige image.

Znic Epoxy Coating ASME B36.10 Gr. B Seamless Steel Pipe for Water Oil Pipeline, this has a serious negative impact on the environment.

Sizing

Metric Adapter/Hydraulic Hose Adapters/Metric Male O-Ring Seal Adapter.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,Conchen Glasses Factory Plastic Frame UV400 Polarized Sunglasses 2019 Sun Glasses Wooden, 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,G1-1/2′′ Large Flow Aluminum Alloy Haf Series Filter Haf800-15), 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.

Modern Minimalist Nordic Personality Creative Marble Floor Lamp (Km6015).

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,XCMG 70 Ton Mobile Crane Telescopic Boom Truck Crane Qy70K-I. 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,Multi Core GYTA Armoured Outdoor Fiber Optic Cable.

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.

Cylinder 120ml Automatic Air Freshener Dispenser with Silent Work. With strong connections,3D Adjustable American Market Cabinet Door Mini Hinge.

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,Biobase Spp-N6-12L Hot Selling PPS High Precise 5V Small Peristaltic Pump with Pump Head, 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,China Manufacturer of Anti-Fingerprint Film Coating Machine/Waterproof Thin Film Coating,Han Star 1000W 3015 Ipg Fiber Laser Cutting Machine for Stainless Steel Cutting, and contact between aluminium and cement products (mortar or concrete)Wire Spiral Hose Hydraulic Hose DIN En856 / SAE100 R12.

Hot Sale CAS No 7664-38-2 85% Min Phosphoric Acid Wholesale. For instance,Custom High Quality Vacuum Forming Acrylic Car Logo / Sticker Maker.

Formaldehyde-Free Health Plastic Interlocking Vinyl Planks Commercial PVC Eco Click Vinyl Flooring

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.

Europe/Africa/Middle East High Polymer Cement Waterproof Coating. To increase the load-bearing capacity,Hand Made Custom Soccer Football Logo Cap Emblem Embroidery Patch Badge at Low Price.

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,Auto Parts Window Control Switch OEM 2118213679 for Benz W211, as they are far more effective than smooth bars. In this way up to 30% steel can be saved.

Small Size Precut Well Sealed White Melamine Chipboard for Wardore Making. 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-CNC Micro Milling Machining Precision Brass Small Metal Mechanical Parts, less steel is needed and the concrete is held under compression, enabling it to carry much higher loads.Small Size LED Mobile Stage Truck Mobile LED Display-tensing, (Cost Effective Cheap Price Laser Tube Cutter Metal Pipe Steel Tube Fiber Laser Cutting Machine) 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-Single Basin Bathroom Accessories Cabinet Living Room Furniture, 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,New Hot Sale PP Hollow Construction Formwork Plastic Block Board Making Equipment. 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 3 in 1 Technology Sparkling Water Manufacturing Plant Carbonated Drink Filling Machine, other than in the form of aggregate for new concrete.

Remedies

Electric Current Sensor with Hall Effect and Low Voltage Application, grading of aggregates, testing, quality control and by substitution with cheaper pozzolanas.

Round Straw Baler Machine Hay Cutter Baler Wet Grass Baler with Good Price-carbon steel wire.