Frame materials

Bicycle frames are made from the following materials:

Hi Ten(Hi Tensile Steel) - high-strength steel, this is the cheapest material. In common parlance - a water pipe. The frame is heavy and does not roll. Doesn't cost anything at all. Bicycles with steel frames cost no more than $300.

Cro Mo(cromomolibden) - chromomolybdenum alloys. Frames made from this material are lighter than those made from Hi-Ten, more rigid, but also more expensive. A good chrome frame costs from $500. Cheap varieties of chromium-molybdenum alloys are no different from hi-ten, well, they roll a little better, weigh a little less. At one time, manufacturers took such a bad fashion: they put only one chrome pipe, and all the rest are hi-ten and proudly write that the frame is made of chrome-molybdenum pipes. If the price tag is below $500, they are lying. Bikes with chromoly frames start at $1,000.

Alu(Aluminum) - aluminum alloys. This material allows for an even stiffer and in many cases lighter frame than chromoly. Commonly used alloys 6061 ,7005 , less often Altec-2, Magnesium, Scandium, and the latter is insanely expensive. The range of frames is very wide, from "stools" that are terrible in terms of rigidity, to full "sausages", from non-rolling graves to downright rockets. A good training KK frame costs $300-500. Sports frames - over $500. On bikes in the sub-$700 price range, the frame costs next to nothing, with the rare exception of custom builds. Cheap aluminum frames (on bikes up to $500) for a similar application do not differ from each other in anything other than size, length and color. Small frame differences start at over $700, and noticeable differences start at $1200.

Ti(Titanium) - Titanium. A very durable material, but at the same time soft (compared to Alu frames, for example), which not everyone likes. Before buying a titanium frame, it makes sense to ride it first and understand for yourself whether it is necessary. Titanium frames start at $400.

Carbon(carbon fiber). These are ultra-light frames, but extremely unstable to shock loads. They cost a lot, so they are used either by the pros or by those who can afford it. Technologies do not stand still, so they learned to bypass instability to shock loads in critical places with purely constructive solutions. And the carbon components themselves are becoming stronger and longer lasting, and prices are dropping. For example, at the Taiwanese factory, a fully carbon frame with at least some calculated geometry, the frame costs ~ $ 150; an aluminum frame with "standard" geometry carbon rear stays costs $20-$30. The quality, you know, is killer.. When choosing a carbon frame, it makes sense to focus ONLY on the name of the manufacturer, it must be a serious brand.

Steering column

The 1 1/8" size has become the current headset standard. There are other sizes, such as 1 1/4", but this is rare.

Regular and semi-integrated steering columns are now standard. There is no functional difference between them, but the semi-integrated one is a bit lighter. Therefore, do not bother.

If we consider the long-term perspective of the operation of an aluminum frame, about eight years, with runs over 5000 km per year and year-round use, then a "regular" steering column should be preferred, because the head tube of the frame for a semi-integrated steering column will break faster than a standard one. Naturally, if this frame is able to live so long.

Rooster

The cock is a metal bracket on which the rear derailleur is attached. It is removable and non-removable. It is preferable that it be removable, because. in the event of a breakdown, you simply put a new one, and the fixed one will have to be welded to the frame. On the vast majority of bikes over $300, the cock is removable.

The bicycle frame is designed to hold the handlebars in front of the owner and the wheels underneath. There are many shapes, metals, colors and frame designs. It is the frame that should be the first significant factor when choosing the whole bike, both when assembling it and when choosing a finished copy in the store. After all, the frame determines the purpose that the bike will perform, the rider's landing, the essence and severity of body kits and mounts. It also makes a big difference to the final weight of the bike. What difference does it make how much the bike weighs?

Aluminum Frame Bicycle

What difference does it make how much the bike weighs

There are three basic parameters that affect the weight of a bike - its stability on the road surface, handling during maneuvers and inertia. The last parameter takes into account not only the inertia itself, but also the energy that must be expended to compensate for it. No matter how strange it may sound, but when the weight of the bike drops, then all these indicators improve. The rule does not work here - the heavier, the more stable, since you often have to change the center of gravity, and inertia is more difficult to compensate.

So the weight of the entire bike is extremely important, and the frame carries most of the weight.

It can be a steel frame, aluminum or chrome-molybdenum. Sometimes there are titanium specimens. Weight depends not only on the frame, but also on all parts of the kit together, as well as on the purpose of the bike. Road versions usually weigh 8-9 kilograms, mountain ones vary - there are lightweight options with a weight of 9 kg, average adult devices weigh up to 11 kg, and downhill specimens can reach an average weight of 20 kg.

Individual sports bikes are expensive and weigh a strictly adjusted number of kg, but they vary too much depending on the manufacturer and purpose, so it makes no sense to indicate their average weight. The cheapest hodgepodge bikes from Auchan and other large hypermarkets cost little, but their equipment is usually heavy, unreliable and inharmonious. It will be inconvenient, hard to ride on this, and it will quickly become unusable, and, as a rule, they cannot be repaired.

steel frame

Both a steel frame and a frame made of various alloys with steel have approximately the same weight. In order for the frame to be as strong as possible, chromium or molybdenum is added to the alloy. This additive also allows you to make unusual frame designs - thinner in the middle and thicker towards the edges. This makes the frame lighter and more comfortable, and an interesting appearance attracts attention, especially in combination with the original color scheme. Compared to aluminum tubes for the frame, these are thinner and more elastic.

When using a steel frame, there is no need to install a carbon fork or frame on the bike. After all, the more flexible the frame is, the longer it will serve its owner. For a touring bike, this will be the best option, as they are inexpensive, but at the same time they lend themselves well to minor repairs. The problem with a steel bike is that it rusts easily and is heavier than an aluminum frame. The advantages of this frame made of such material include:

• Excellent inertia - after the owner has stopped pedaling, the bike maintains excellent speed for a long time;
• Soft steel frame - steel softens shock and vibration, combined with a carbon fork, makes cycling a pleasure;
• Bend - often a steel frame bends at unusual angles, which helps a lot when cornering;
• Durability and excellent material repair ability - every second welder can help.

But such a frame also has a small number of disadvantages, including increased weight - in the lightest versions, such a frame will weigh 1 - 1.5 kg more than other options.

Sharp acceleration on such a frame will also not work.

aluminum frame

Now most bikes are made with an aluminum frame. Such specimens are lighter, more responsive to road irregularities, inexpensive both to repair and to buy, and they are not subject to corrosion. The rigidity and weight of such a frame will be better than that of steel, but the metal itself will have a lower density. The aluminum frame is light and rigid, although the diameter itself is larger at the pipe. If compared with steel, then increasing the diameter of the pipes of such a frame will lead to a more rigid version, but at the same time it is an order of magnitude lighter.

There will be practically no change in stiffness, but if it is felt, then you can put carbon forks on the bike that will soften the road.

Broken aluminum frame

The advantages of an aluminum frame include:

• The best possible ratio between weight and cost of the final result. The lowest-grade frame does not weigh more than 2 kg, and good quality - no more than 1.5 kg;
• Sharp and good acceleration on any terrain;
• Aluminum does not corrode metal;
• It is the best option for heavier cyclists.

The disadvantages of this frame are in direct contrast to the advantages of a steel frame.

1. A frame made of such material not only accelerates quickly, but also quickly loses all its inertia.
2. It is rigid - aluminum cannot dampen vibrations when riding. In combination with a rigid fork, skating can turn into torment.
3. People with a small weight will have difficulty riding it.
4. Such a frame will not last more than 10 years, as it accumulates its fatigue and simply bursts at the most inopportune moment.
5. Not every breakdown of such a frame is also subject to repair.

Frame material selection

John Olsen- Last modified: 2010-07-02

Titanium, carbon fiber, aluminum or steel - What is the ideal frame material?

Text version: 1.0

The original translation of this article is here: http://velosamara.org.ru/.
This material has been reprinted with the permission of the author of the translation.

From the translator

When I was about to write an article about the properties of different materials for frames, I found an article on the Internet by John Olsen about frames made of various materials. It seemed interesting to me and did not contradict my concepts of strength (after all, by education I am a specialist in the strength and durability of aircraft structures, I worked for several years in the aircraft strength laboratory in KuAI). The language of the article seemed to me quite understandable for a non-specialist, which is also a big plus.

To be honest, I did not look for a translation on the Russian-language Internet (maybe there already is) and translated the article myself. Olsen covered most of the problems that I was going to write about - I see no reason to repeat what has already been written and, in my opinion, is quite understandable, sensible and fair.

The article does not mention the terms "specific strength" and "specific stiffness" accepted among specialists, meaning the ratio of strength or stiffness values ​​to the density of the material, and characterizing how strong (or rigid) the material is per unit weight, but indirectly it is made clear that these characteristics are taken into account by the designers.

And one more thing - it should be distinguished when it comes to the strength (rigidity) of the material, and when - about the same properties of the structure. In the structure (frame), to increase the strength and rigidity, the diameter of the pipes is increased, the shape of their section is changed, different (including variable along the length of the pipe) wall thicknesses are used, etc. - and all this - to compensate for the insufficient properties of the material. On the other hand, a larger diameter pipe usually weighs more than a smaller diameter pipe of the same material - but the larger pipe is stiffer. There are also technological factors not discussed in this article (ease of processing, weldability, etc.), but affecting the choice of designer.

For my part, I decided to write .

Introduction

The stiffness, weight and strength of bicycle frames are determined by many factors, only some of which are determined solely by the properties of the material. A frame design that is optimal for one material will not be optimal for another because materials vary greatly in strength, stiffness and density (weight).

The best aluminum frames have thick, thin-walled tubes and don't flex side to side as you accelerate. The best steel frames have thin-walled small-diameter tubes and flex noticeably during acceleration. Titanium and carbon fiber (carbon) frames are in the middle between them.

Experienced cyclists are often divided into two camps, with steel framers criticizing the excessive rigidity of aluminum frames and aluminum frame aficionados decrying the flexibility of lightweight steel frames. We will explain the advantages and disadvantages of most frame materials and compare them with a graph showing how stiff they are compared to steel.

How stiff is your bike?

Comparison of stiffness (relative to steel) for various frame materials

Steel

Steel is tough but dense (heavy). Light frames of adequate stiffness and strength are made from relatively small diameter tubes, but steel is not a suitable material for light frames or large strong riders. Low strength steel frames (inexpensive) need thick wall tubing to be strong enough and are heavy. Stronger steel allows the production of thin-walled pipes, but then stiffness decreases. Recent developments include very high strength "air hardened" steels such as Reynolds 853. (Unlike most other types of steel, air hardened steels gain rather than lose strength when they are cooled after welding). All steels have the same stiffness, regardless of strength - 853 is no stiffer than 1010 (low strength steel).

Pros:

• The best steel alloys are very strong
• Best stiffness all around
• durable
• Air-hardenable steel alloys enable ultra-high strength

Minuses:

• Should be heavy - material not suitable for large light frames
• are rusting

Aluminum

Aluminum frames can be very stiff and light because the density of aluminum is very low, but the frame tubes must be larger in diameter to compensate for the lower strength. Today, however, these "fat-tube" frames are a common design for quality bikes. Recent improvements include the addition of scandium, an element that increases strength. In general, aluminum is a good material for stiff, lightweight frames for riders of all sizes. It is also one of two materials that work well for non-traditional frame shapes.

Pros:

• Three times less dense than steel, allows the use of large ("thick") pipes
• Easily conforms to aerodynamic shapes
• Even cheap frames can be light
• Allows you to make a lightweight frame for a large rider
• Doesn't rust

Minuses:

• One third to half the strength of the best steels (may break)
• One third of the stiffness of any steel, large diameter pipes required
• Modest fatigue strength
• Not easily repaired or restored
• Large, thin pipes are easily damaged in an accident

Titanium

Titanium has an excellent balance of properties for frame construction and offers the best combination of durability and weight. Titanium alloys are half as hard as steel, but also half as dense. The best titanium alloys are comparable in strength to the strongest steels. Rigid titanium frames require larger diameter tubes than comparable steel frames, but not as large diameter as aluminum. Titanium is very corrosion resistant and very light frames can be made stiff enough and strong enough for big riders. Most titanium frames are 3Al/2.5V (3% aluminium/2.5% vanadium, the rest titanium), although the stronger alloy 6Al/4V (6% aluminium/4% vanadium, the rest titanium) is increasingly being used.

Pros:

• Half density steel, makes the most flexible frames lightest
• As strong as most steels
• Will not rust - no painting required
• Good fatigue properties
• Allows you to make lightweight frames for large riders

Minuses:

• Half the stiffness of steel (also known as overflex)
• Difficult to repair and process
• Expensive

CFRP

Individual carbon fibers are extremely strong and tough, but these properties are useless unless the fibers are arranged in a strict structure and held together with a strong "glue" (usually epoxy). Unlike metals, where strength and stiffness are nearly the same in all directions, carbon fiber composites can be produced with higher strength and stiffness characteristics in the directions that are needed (e.g., rigid laterally and flexible vertically). It is the best material for frames of non-traditional shapes, as it allows you to mold and customize its properties like no other metal (by creating multi-layer structures with differently oriented fibers).

Pros:

• Easily molded into exotic shapes
• Excellent fatigue strength
• Doesn't rust
• Strength and stiffness are controlled at the stage of frame creation
• Low density and high strength make it possible to create very light and strong frames

Minuses:

• very expensive stuff
• "Bomb" - if the product is poorly designed or manufactured (too rigid or too flexible) - can be "sensitive" (prone to breakage).

Aluminum frame bikes are among the most common on the market today. This is due to the lightness of the material, combined with low cost. If steel has a specific gravity of 7.8 grams per cubic centimeter, then aluminum has a specific gravity of about 2.7 grams. In terms of wall thickening, this material also outperforms iron, since the minimum parameter is 0.8 mm, while the product will weigh less than a 0.4 mm thick steel frame. Reliability is further enhanced by the absence of welded seams. In addition, they can be performed in various configurations. Consider their features, advantages and disadvantages.

Description

Aluminum-framed bikes are lighter in weight and gain speed faster and are easier to climb. For the same reason, the bike stops faster after the rider stops pedaling. Aluminum in its pure form is not used, this material means its alloy with zinc, manganese, nickel, copper or magnesium.

These bikes are more difficult to get into tight turns, because they are stiffer than their steel counterparts, they can not bend as well. Due to the rigidity of the frame, the energy from the efforts of the cyclist is transferred to the wheels with less loss. Such subtleties play a role for professionals, for amateurs this is not a critical indicator. A stiffer and less comfortable ride becomes noticeable. Bicycles with an aluminum frame practically do not dampen the vibrations transmitted to the saddle and handlebars on uneven surfaces and bumps. A bike like this requires a good suspension unit and a comfortable saddle. This will allow part of the blows to be leveled, which will favorably affect the movement.

pros

Let's start with the advantages of the product in question. These include:

• Light weight for improved speed and acceleration.
• Maximum resistance to corrosive processes.
• High driving performance even when driving uphill.

Minuses

Bicycles with an aluminum frame have a number of disadvantages, namely:

• High rigidity, which is especially felt on models without a suspension fork.
• Rapid roll loss. Due to its light weight, the bike stops faster than its steel frame counterpart after the rider stops pedaling.
• A small working resource during active operation. After a few years, cracks may appear. Manufacturers give a guarantee of 5 to 10 years, but after this period it is recommended to lubricate the part to check for possible deformations.
• When dropped on an aluminum frame, there is a higher chance of dents.
• Poor maintainability. It is very problematic to weld such a part, it is better to purchase a new one.
• Pretty high price.

Folding bikes with aluminum frame

Below we list several popular brands of this type and name their brief characteristics:

1. The expensive city bike Strida SX has an original exterior. It folds down to the size of a compact cart that can be transported on its own. The steering wheel can also be transformed. The advantages of the bike include the fact that the cables and wires are hidden in the cavity of the frame, it is easy to assemble, there is a trunk, disc brakes. With good maneuverability, the device weighs only 11.6 kg. Among the minuses are a small carrying capacity, narrow wheels, poor depreciation.
2. Smart 20. Stylish city bike, considered one of the best in its price category. Can be used by women without any problems. Among the advantages are a solid frame, a convenient transformation mechanism, the presence of reflectors and other accessories. The disadvantages include the lack of a handbrake and the quality of centering of the wings.
3. Stealth bike. The aluminum frame of the Pilot-710 model does not interfere with the softness of the ride. The transport picks up speed well on coast, has a discreet design, fits into the luggage compartment of any car in the folded position, is equipped as standard with a luggage rack and chain protection. The disadvantages are the presence of a wide steering wheel and an uncomfortable fit for tall people. The intended purpose of the modification is city trips.

Children's bicycles with an aluminum frame

Below is a brief description of some children's and teenage models:

• Mars. This one is for kids ages 3 and up. Comes with extra polyurethane wheels. The frame and fork are made of aluminum alloy, there is a handlebar height adjuster. Wheel diameter - 12 inches, model weight - 4.5 kg.
• Forward Timba‏. One of the best for kids 6-9 years old. It has a beautiful design, affordable price, chain protection and removable safety wheels. The disadvantages include a decent weight (almost 14 kg), as well as the need to adjust some moving parts.
• Shulz Max. These children's aluminum frame bikes are in the middle price range. The weight of the bike is 14.3 kg. It is aimed at adolescents 12-16 years old, has a load capacity of up to 110 kg. The advantages of the model are the ease of assembly / disassembly, a good set of speeds, equipment with 20-inch wheels and quality. Among the minuses are incorrect factory adjustment, brake pads of dubious quality.

Peculiarities

When choosing a bike, the question often arises of whether to choose an aluminum or steel bike frame. The final decision depends on the financial capabilities of the buyer, the purpose of the machine and the subjective requirements of the user. It should be noted that thick-walled pipes of large diameter are used in the manufacture of aluminum structures.

This is due to the fact that, according to the laws of physics, if the pipe size is doubled, its rigidity will increase by eight times, and if the wall thickness is doubled, the stiffness index increases by the same amount. Therefore, of the available options, increasing the diameter is preferable.

As a rule, the minimum wall thickness of a pipe on an aluminum frame is 0.8 mm. Often manufacturers make pipes by butting or using different sections, which also makes it possible to strengthen the product.

Used alloys

There are many aluminum alloys that are used to make bicycle frames. The most common are the brands 7005T6 and 6061T6. The T index indicates that the material has undergone heat treatment. For example, a 6061 alloy product is heated to 530 degrees Celsius, then actively cooled by a liquid. Further, for 8 hours, the material is artificially aged at a temperature of 180 degrees. The output is 6061-T6. Analog number 7007 is air-cooled, not water-cooled.

Below are the comparative characteristics of the materials before and after heat treatment (in parentheses):

• Alloy 2014 (2014T6) - tensile strength is 27 (70) thousand PSL, yield strength - 14 (60), elongation percentage - 18 (13), Brinell hardness - 45 (135).
• Similar indicators of material 6061 (6061T6) - 18 (45), 8 (40), 25 (17), 30 (95).

The first alloy uses 4.5% copper, 0.8% carbon and manganese, 0.5% magnesium. The second material includes 1% magnesium, 0.6% silicon, 0.3% copper, 0.2% chromium, about 0.7% iron.

Finally

The strongest bike is 16 ”, the aluminum frame of which is made of 70005 or 7005 alloy. Nevertheless, the 6061 analog is more technologically advanced, which makes it possible to make pipes with a complex section from it, and this increases the strength of the product. In addition, such aluminum lends itself better to welding. When choosing a frame, consider the financial possibilities and the intended use of the bike. With proper maintenance, a bike with a frame made of any material, including steel, aluminum or carbon, will last for quite some time.

frame metal structures are distinguished by a wide variety of static schemes, the number of spans, configuration, etc., which makes it possible to build buildings of various purposes and sizes.

Figure 3.2.1 shows some types of flat and spatial steel frame structures. Static schemes of frame structures are shown in Figure 3.2.2.

Most often, the sections of frame structures are made of solid I-beam or box section. Some possible options for solid sections of steel frames are shown in Figure 3.2.3.

The use of one or another type of frames, their static scheme and type of section is determined by the size and configuration of the building being designed, the availability of appropriate technological equipment for the manufacture of structures, and other factors.

Depending on the calculation scheme of the frame, the crossbars are of constant or variable section. In double-hinged frames (Fig. 3.2.2 c), the height of the crossbar of constant height is taken equal to 1/30-1/40 of the span. Racks usually have a variable section, decreasing towards the supports.

With spans of more than 50-60 m, through (lattice) frames are economical (Fig. 3.2.4). In double-hinged through frames with hinged coupling of racks and foundations, the height of the crossbar of the frame is taken within 1/8-1/15 of the span.

Hingeless through frames, usually used in hangar covers, have very large spans (120-150 m). The height of the crossbar in such frames is taken equal to 1/12-1/20 of the span. In hangar construction, double-console and single-console frames are also used. Single-console frames are suitable for canopies of sports facilities. In buildings with a span of 40–50 m and a height of 16–20 m, it is possible to use through double-hinged frames with a broken crossbar (Fig. 3.2.1 h) of a constant height equal to 1/15-1/25 of the span.

The lattice of crossbars of through frames is usually taken triangular. Racks of frames can be designed solid (Fig. 3.2.4 a) or lattice (Fig. 3.2.4 b). Lattice racks can have a triangular or diagonal lattice. The sections of the rods and the nodes of the through frames are designed similarly to the trusses of large spans. However, it is most expedient to use bent profiles of rectangular section.

Below are examples of typical frame structures used in industrial buildings.

Fig.3.2.1. Types of frame structures

a - a frame made of flat frames; b - from spatial frames; c - a spatial frame of flat frames and power spatial connections; g - single-span frame; e - multi-span frame; e - U-shaped frame; g - a frame with a slope of racks and crossbars; h - polygonal outline frame

Fig.3.2.2. Static schemes of frame structures.

a - double-hinged frame; b - three-hinged frame; c - frame with rigid support of the uprights on the foundations and rigid junctions of the crossbar with the uprights; g - a frame with rigid support of the racks on the foundations and hinged joints of the crossbar-rack; e - a frame with hinged end and intermediate posts, rigid junctions of the crossbars with the end posts and a hinged connection with the middle ones; f, g - frames with split or continuous crossbars hinged on pinched posts; h - a frame with a developed middle stance, which acts as a core of stiffness; and -, k - mixed schemes.

Fig.3.2.3. Types of sections of frame structures.

a - from welded I-beams of constant or variable section with flat walls; b - from rolled I-beams of variable height, formed from ordinary ones by diagonal dissolution and welding; c - from rolled I-beams without reinforcement and with reinforcement with haunches; g - from welded I-beams with a corrugated wall; e - box-section (type "PLAUEN" or "ORSK").

Rice. 3.2.4. Lattice frame types

a - with solid racks; b - with lattice racks

Frame structures according to series 1.420.3-15 "Steel frame structures of frames of the Kansk type" of one-story industrial buildings using load-bearing frames made of rolled wide-shelf and welded thin-walled I-beams "are designed for one-story buildings with spans of 18 and 24 m, the number of spans from one to five and a height of 4.8 - 10.8 m to the lower girder of the crossbar. Frame spacing for single-span buildings, 6 m is adopted, and for multi-span buildings - 6 and 12 m.

The building can be equipped with overhead cranes with a lifting capacity of 1 to 3.2 tons or overhead cranes of light and medium duty with a lifting capacity of 5 to 32 tons.

For structures of the Kansk type, two options for solving the ends have been developed:

With the presence of frames at the end, offset by 500 mm inward, and a non-bearing fachwerk;

Instead of frames, an end-bearing fachwerk is installed at the end, including racks, horizontal beams and vertical ties.

The option with non-bearing fachwerk is used in cases where it is planned to expand the building in the future, while the end frames will serve as twin frames of the expansion joint. The second option is appropriate if further construction is not provided.

The crossbars of the frames are designed from thin-walled welded beams, and the posts are made from rolled wide-shelf I-beams. The coupling of crossbars and racks of single-span frames is rigid. The crossbars of the multi-span frames are hingedly connected to the columns of the outer rows, and rigidly to the columns of the middle rows.

The racks of the supporting fachwerk are designed from cold-formed thin-walled box-section profiles or from composite C-shaped profiles.

In buildings with overhead cranes, the crane tracks at the end of the building are attached to half-timbered posts or to supporting steel beams.

In buildings with overhead cranes, a built-in crane trestle is installed, consisting of racks rigidly fixed to the foundations and typical crane beams laid on them.

In the longitudinal direction, the rigidity of the building is ensured by vertical ties installed along each row of columns and racks of the crane trestle in the middle of the temperature block with a length of no more than 72 m.

According to the series, all mounting units of frames of the Kansk type are bolted, which excludes the use of welding at the construction site.

The layouts of the frame elements and nodes of steel structures of the "Kansk" type are shown in Figure 3.2.5 - 3.2.7.

Rice. 3.2.5. Frame structures of the "Kansk" type

Rice. 3.2.6. Structural units of frame structures of the "Kansk" type

The nodes are marked in Figure 3.2.5.

Rice. 3.2.7. Structural nodes and fastening of crane tracks for frame structures of the Kansk type

Frames from I-beams of variable section(codes 828 KM, 828 KM-1, 941 KM, 961 KM) are used in one-story single-span industrial buildings with spans of 18 and 24 m and with a crossbar top mark of frames 6.940 and 8.140 m without light-aeration lamps. The frame spacing is 6 m. Buildings can be equipped with overhead cranes with a lifting capacity of up to 3.2 tons.

The frame of a building with frame structures consists of transverse frames, purlins, vertical braces and braces along the frame posts, posts and beams of the end fachwerks.

Elements of variable I-section in the crossbar and posts are made from rolled I-beams with parallel flange edges by their longitudinal dissolution along an inclined line into tees of variable height.

The connection of the racks with the foundation is assumed to be articulated. The conjugations of the elements in the cornice and ridge assemblies are assumed to be rigid and are made on 25 mm thick flanges using high-strength bolts.

The rigidity of the frame in the transverse direction is ensured by the operation of the frames, in the longitudinal direction - by vertical cross braces and struts along each row of frame racks, which ensure the stability of the racks from the plane of the frames.

The slope of the upper chord of the crossbar is assumed to be 0.025 when using a typical roll roofing and 0.100 when using roofing panels with metal sheathing.

The bearing end fachwerk is designed from wide-shelf I-beams.

Frame diagrams and junctions of frame structure elements are shown in Figure 3.2.8.

Frames made of I-beams of variable section are widely used in the construction of industrial and public buildings. Frame structures can also be cited as an example. "ASTRON".

They use welded I-beams of both variable and constant section. Single-span buildings with overlapping spans of up to 72 m have been developed. With additional internal supports, overlapped spans can reach 150 m. The frame spacing is taken from 5 to 12 m. The height along the gutter can reach 20 m. If necessary, frames of other geometric dimensions can be developed .

Buildings can be equipped with overhead cranes with a lifting capacity of up to 20 tons.

Frames are usually hinged to the foundation. However, if necessary, the connection can be rigid. The end fachwerk is carried out as a carrier of welded or hot-rolled racks and crossbars. Coating purlins are adopted from cold formed galvanized Z-profile.

An example of a building made of frame structures "ASTRON" is shown in Figure 3.2.9.

Rice. 3.2.8. Steel frame structures from I-beams

variable section

Flat frame system box-section frame type "Orsk"(code 135, series 2.420-4 issue 3) consists of single-span transverse frames, spaced in 6 m increments, girders, vertical braces, racks and beams of end fachwerks. It is not recommended to use Orsk-type structures in multi-span buildings.

Frame structures are designed for heated buildings with spans of 18 and 24 m, having a height of 6980 mm and 8180 mm to the top of the frame crossbar on the support. They are used in buildings without lanterns and in buildings with skylights, craneless and with overhead cranes with a lifting capacity of 5 tons. The slope of the frame crossbar is assumed to be 1.5%.

The pairing of the frame racks with the foundations is assumed to be articulated. The conjugations of the elements in the ridge and cornice units are assumed to be rigid and are made on 16 mm thick flanges using high-strength bolts.

Schemes and nodes of frame structures of the "Orsk" type are shown in Figures 3.2.10 and 3.2.11.

UNITEC steel frames of one-story industrial buildings using structures made of bent-welded pipes are designed for use in heated and unheated buildings without cranes, with overhead cranes with a lifting capacity of 1 to 5 tons and with bridge overhead cranes with a lifting capacity of 5, 10 and 16 tons with operating modes 1K-5K with non-aggressive or a slightly aggressive environment with a relative humidity of no more than 70% indoors.

Cranes are suspended symmetrically about the central axis of the frame span. At the ends of the building with overhead cranes, the crane tracks rest on beams or directly on the racks of the supporting half-timbered frame.

As enclosing structures, as a rule, panels with profiled sheet sheathing or layered assembly structures for heated buildings and profiled sheet for unheated buildings are used.

The main load-bearing structures of UNITEC frameworks are through single- and multi-span frames made of bent-welded pipes. The step of the main supporting structures is 6 m. If necessary, with large vertical loads (snow bag, etc.), the step of the frames can be reduced.

The coupling of the structures of the outer racks of frames with the foundation is articulated, the middle racks of frames and racks of half-timbered houses are rigid.

The connection of the crossbar of the frame with the outer posts is rigid, with the middle posts - articulated.

The mark of the bottom of the supporting structure of the crossbar at the point of junction with the extreme rack of the frame ( H) is provided from 4.8 to 14.4 m.

The binding of the extreme racks to the longitudinal axes is accepted as "0" or "250" for spans of 12 - 18 m, depending on the possibility of placing an overhead crane. In craneless buildings with a span of 21-30 m, zero binding is accepted.

The length of the temperature block is not more than 96 m.

At the end of the building, a load-bearing end fachwerk is installed, consisting of racks and beams. The rigidity of the half-timbered system is ensured by the installation of a system of flexible connections and struts. In the case of the proposed expansion

the main bearing frame with self-supporting half-timbered racks is installed at the end of the building.

The stability and geometric immutability of the building is ensured by:

in the transverse direction - by the structures of the supporting frames;

in the longitudinal direction - a system of vertical ties and struts.

The rigidity of the coating is provided by a system of horizontal braces and spacers along the crossbar of the frame.

Coating runs are made according to the cut scheme. The spacing of the roof runs is assumed to be 1.5 or 3.0 m, depending on the load on the roof and the bearing capacity of the roofing enclosing structures. With a run spacing of 1.5 m, the crossbar lattice is made with additional posts. The sections of the coating runs are taken from rolled and bent channels.

The wall purlins are made according to the split scheme. The spacing of wall purlins is assigned from 1.2 to 3.0 m in multiples of 0.6 m in accordance with the location of windows, gates and other openings, as well as depending on vertical and horizontal loads and the bearing capacity of wall enclosing structures. Sections of wall girders are taken from rolled and bent channels, as well as from bent-welded pipes.

Horizontal and vertical ties on the frame and fachwerk - cross flexible from round steel Ø 20 and Ø 24 mm.

Spacers between frames are made of bent-welded pipes.

All factory connections are welded. Mounting connections on bushings and on ordinary and high-strength bolts.

Dimensional diagrams of buildings with overhead cranes are shown in Figure 3.2.12, structural junctions for frames - in Figures 3.2.13 and 3.2.14.

Buildings equipped with overhead cranes with a lifting capacity of 5, 10 and 16 tons can be single or double-span with a span of 12 and 18 m with a mark to the bottom of the crossbar H from 6.0 to 14.4 m.

steel arches can also have a solid or through section.

Solid arches usually have a constant cross section and are used for spans up to 60 m (Fig. 3.2.15). The sectional height of such arches ( h) is usually taken equal to 1/50 - 1/80 of the span ( L). With spans of more than 60 m, through (lattice) arches are usually used. The height of the section in this case is 1/30-1/60 of the span. Geometric schemes and types of sections of through frames are shown in fig. 3.2.16.

The most widespread are metal arches operating on a two-hinged scheme. The design of the support hinge is determined by the span of the arch and the magnitude of the acting load. Figure 3.2.17 a shows the simplest design (with the help of a tiled hinge), typical for a light arch of a solid section.

Rice. 3.2.10. Steel frame structures of box-section type "Orsk

Rice. 3.2.11. Schemes of end faces, arrangement of girders and vertical connections in buildings with steel frame structures of box section of the "Orsk" type

Rice. 3.2.12. Dimensional schemes of buildings using

frames UNITEC

The most complex solution, with the help of a balancing hinge, is the support units of heavy large-span arches (Fig. 3.2.17 b). Because near the support, the sections of the through arches turn into solid ones; the supporting nodes of such arches are performed similarly.

Rice. 3.2.13. Eaves and support units of the UNITEC frame

(nodes are marked in Fig. 3.2.12)

Rice. 3.2.14. Overhead track beam attachment points

and half-timbered racks to the frame crossbar

Rice. 3.2.15. Structural scheme and types of sections of solid arches