Anchor bolts— if we consider the principle of operation of the two main types of fasteners - the anchor and the dowel, then the anchor has a significant advantage. The metal anchor, in addition to the frictional force, is held at the base using a “stop” in the form of a kind of anchor, obtained due to the spacer part of the shank. To friction is added the force of resistance to destruction of the base material.
There is also chemical anchors, they use quick-hardening instead of a metal sleeve adhesive compositions, which are inserted into the hole before installing the anchor bolt. The result is a monolithic connection with the base.
There is a large range of anchors on the market, but they can all be divided into several classes.
Anchor bolt with nut: how to fasten
Essentially, it is a stud with a nut and washer that is screwed into a coupling (threaded sleeve). Therefore, it can be called an anchor bolt with a nut or a stud anchor. We study in detail how to fasten anchor bolts with a nut ourselves and use them.
Anchor bolt (foundation bolt) with nut
On one side, a nut and washer are screwed onto the stud, and on the other, there is a “wedge” in the form of a cone. In the wide part the wedge corresponds to the diameter of the coupling, in the narrow part it corresponds to the pin. The coupling on the wedge side has a notch and longitudinal slots.
Installation is quite simple, even a beginner can understand how to attach anchor bolts with a nut.
Anchor bolt: fastening diagram
A hole for the coupling is drilled in the base and cleaned of dust. The part is hung on the anchor, inserted into the hole and hammered in with gentle blows of a hammer until it stops. Then tighten the nut a few turns.
Screwing onto the stud, the nut “unscrews” it from the coupling; as a result, the wedge expands the coupling along its entire length with slots.
Anchor bolts are made from galvanized steel. Used for concrete, stone, solid brick.
There is an “improved version” of such an anchor - a double-spacer one.
Double-spacer anchor bolt
It has two movable couplings with slots, one of which fits into the other with a cone. When the nut is screwed in, the shank pushes one sleeve onto the other. The first one expands with a wedge cone and itself expands the middle coupling, forming two fastening belts.
Wedge anchor - how to attach
This type can be considered as a modification of the previous one. The coupling is made in the form of a movable short sleeve-ring at the end of the pin on the shank (wedge) side.
The principle of operation is similar, there is a slight difference - it is not required precision drilling according to the depth of the hole and cleaning it from dust. The hole is drilled with reserve, the anchor is inserted to the required depth and the nut is screwed in, pushing the sleeve apart with the shank.
Anchor stud with hex head
This is a classic bolt and washer that screws into a coupling with longitudinal slots at the end. The tail cone-shaped nut serves as a spacer element.
Installation is standard - drill a hole, clean it, insert an anchor with a suspended part and lightly tap it. All that remains is to tighten the anchor bolts a few turns - the nut fits into the coupling with a cone and pushes it apart.
Anchor stud - installation diagram
Scope of application is the same as previous types- fastening heavy structures to a base made of concrete, stone and solid brick.
This type of bolt may end in a ring or a hook. They allow you to simply hang structures after installing the anchor, otherwise there are no differences.
Impact anchor bolts - how to attach an anchor bolt.
This sample combines the functions anchor and nail.
Impact type stud anchor
It consists of a hollow metal rod, one end of which is made in the form of a stud with a thread for a nut and washer, the other is a sleeve with a four-leaf spacer.
Installation, how to fasten an anchor bolt - you need to drive an anchor bolt into the hole in the base, into which in turn a nail is driven. The petals of the sleeve diverge. The nut serves only to secure the part being hung.
Four-segment expansion anchor
According to the principle of operation, this type is closer to an anchor with a nut or hex head. Although it does not have a wedge or cone-shaped nut on the shank of the stud or bolt, expansion occurs due to the bolt itself being screwed into the hollow sleeve, which moves the internal tetrahedral element.
Four-segment anchor bolt
The anchor consists of a cylinder with four slots that end in a narrow ring. The slats are held in place by a flat spring, after which the slots are shaped like a wedge. Moving, the tetrahedral threaded element pushes these wedges apart.
Anchor stud installation diagram
The bolt is not included in the kit, but is selected depending on the size of the structure being hung.
In addition to the bolt, you can screw a bolt with a hook or ring into the expansion anchor. These modifications come with them.
Due to the wide opening of the wedge lamellas, expansion anchors can also be installed in weak foundations - hollow (slotted) bricks, gas or foam concrete blocks.
Driven anchor - how to attach an anchor bolt.
One of the easiest types of anchor to install.
The device is a threaded bushing that has slots at the driven end, a conical internal shape and a wedge.
Installation - a hammer anchor is inserted into the prepared hole and, using a special impact attachment, the cut part is pushed apart with a wedge. When the anchor bolts are screwed in, the petals spread even wider, increasing grip.
Made from galvanized steel or brass.
Screw anchor
Has a special design. The slots in the sleeve are not cut completely and end with a ring with a nut. Closer to the head and in the middle of the liner, the lamellas are weakened. When tightening the screw, the nut moves and pushes the lamellas apart in the middle.
Specially designed for weak and hollow substrates. It can be produced not only with a screw, but also with pins, hooks, and rings.
In order to correctly install anchor bolts, it is necessary to take into account the type and strength of the base, select the optimal type of anchor for a particular part and determine its load capacity.
In order to ensure high reliability of the connection using an anchor bolt, it is important not only to select it correctly in size and type of structure, but also to know how to properly fasten such a product.
There is a wide variety of anchor bolts, differing in their design and principle of operation, so it is important to know how to attach a particular type of anchor
The classic design anchor bolt provides reliable connection not only due to its frictional forces outer surface with the walls of the mounting hole, but also due to the fact that its spacer sleeve increases in diameter when the threaded element is screwed into it. The reliability of installation of such a fastening element is also influenced by the strength characteristics of the material. building structure, which should also be taken into account.
For all fasteners under consideration, the drill for making the mounting hole is selected according to the diameter of the anchor, with the exception of impact-type anchor bolts.
With nut
Structural elements of an anchor bolt of this type are:
- a threaded rod, one end of which is made in the shape of a cone, and a nut is screwed onto the other;
- a spacer screwed onto a stud (its lower end has longitudinal slots on the side surface, which form peculiar petals).
Reliable fixation of such a fastening element is ensured due to the fact that the petals of the spacer sleeve are unclenched, which occurs when they are exposed to the conical end of the pin. In order for the tapered end of such a bolt to begin to enter the bushing and open its petals, a nut is used.
Fasten an anchor bolt with a nut in the foundation or any other building structure made of concrete, performing the following steps:
- drill a hole, the diameter of which should correspond to the size cross section spacer sleeve;
- clean thoroughly mounting hole;
- carefully hammer in with a hammer;
- By tightening the nut, you achieve reliable fastening of the anchor.
After the installation of the anchor bolt is completed, you can unscrew the nut from the top of the stud and begin installing the required item.
When choosing products of this type, you should keep in mind that they demonstrate their effectiveness only if they are mounted in durable and solid materials (concrete, brick, natural stone, etc.). Manufacturers, in order to ensure high reliability and corrosion resistance of such products, make them from high-quality steel with a zinc coating.
An improved model of this type of anchor bolt is a double-expansion anchor, which, due to its design features, can be successfully attached not only to durable concrete, but also in hollow and porous materials. Such a bolt has two bushings at once, which expand during the process of tightening the threaded element, creating more reliable fastening in a wall or foundation.
Wedge
An anchor of this type, the spacer or wedge sleeve of which has a shortened length, is also a modification of a fastener with a nut. The wedge element that expands such a bushing is the reverse end of the threaded part of the bolt, which has a conical shape.
The big advantage of using them is that for their reliable fastening there is no need to maintain the exact diameter of the mounting hole; moreover, it does not need to be cleaned of construction dust. Such a bolt is secured in the mounting hole, and its spacer element is expanded by tightening the nut.
Hex head
The threaded part of such a fastener is a classic bolt, the reverse end of which also has a conical shape. Screwing into the spacer sleeve, such a bolt opens it with its conical shank, ensuring reliable fastening of the product to the wall or foundation.
Such an anchor should be secured by inserting and carefully hammering it into a previously prepared and cleaned hole. Then you need to securely fasten the bolt by tightening its hex head.
Bolts of this type, which may have a hook or ring instead of a hex head, are used to perform installation work on concrete, stone and other building materials with a dense internal structure.
Drums
Anchor bolts of this type consist of:
- a hollow metal rod, on the upper part of which there is a thread for a fastening nut, and the lower part is a spacer coupling with longitudinal slots on the side surface;
- a striking element (nail), which, when driven into a hollow rod, precisely ensures the expansion of its lower part;
- nuts and washers, which are needed only to secure the required object with such a bolt.
Thus, in order to correctly and reliably fasten such a bolt in a wall or other building structure, you must not only insert it into the mounting hole, but also hammer it into it impact element, which will open the petals of the spacer coupling.
Taking into account the fact that when installing such a bolt, significant shock loads arise, it is not recommended to fasten it in porous and fragile materials.
Four-segment
The design of such an anchor bolt does not include a wedge part, and the expansion of the spacer sleeve, divided into four segments by longitudinal slots, occurs when the bolt is screwed in, which moves the tetrahedral element in its internal cavity. The four lobes, which are formed by slots on the side surface of the spacer, are initially compressed and form the conical tip of such a bolt. When a bolt is screwed in, which moves a threaded tetrahedral element inside the spacer sleeve, the segments expand, which allows the anchor to be securely fastened in the mounting hole.
The petals of such a product open quite wide and this happens very carefully. That is why it can be mounted in porous and even hollow materials. The threaded element, which is usually not supplied with such an anchor product, can be a bolt with a regular hex head or a bolt whose upper part is crowned with a ring or hook.
Drivers
A drive-in anchor is the simplest anchor-type fastener, the design of which consists of a spacer sleeve with a conical-shaped internal hole. To install this at the required point of the building structure, it must be hammered into the mounting hole, and then a threaded element must be screwed into it, which will ensure the expansion of the bushing petals.
The material for the manufacture of such fasteners, the process correct installation which can be seen in the video, can be galvanized steel or brass.
Screw
The design of the screw fastener, which is very easy to use, differs from all other anchor-type products. The slots on the spacer sleeve of such an anchor, which ensure its expansion during installation, are made in its middle part and have a weakened design. The lower part of such a sleeve is a nut into which the anchor bolt is screwed, compressing it along its length and ensuring the opening of the petals.
Not so long ago, wooden plugs were used as fastening elements, which had to be hammered into pre-prepared holes. Such products were unreliable and short-lived, as the wood dried out, which led to the fasteners becoming loose. Plastic dowels were also not widely used; they could not withstand heavy weight. To replace wooden and plastic products Modern anchor bolts have arrived, which greatly simplify the installation of suspended structures and do not slip out of the concrete.
To understand in more detail what an anchor is, let’s consider the classification of these fasteners.
Types of anchor bolts
First of all, anchor fasteners differ in their mode of action. They are:
- Chemical. Such products are a capsule with glue, which is placed in the hole. As soon as the anchor begins to screw into the wall or any other surface, the capsule is crushed and the glue polymerizes, securely fixing the fastener. The chemical anchor bolt for concrete is indispensable for hollow slabs. However, these products are different high cost, so they are not so popular. Another disadvantage is that after installing the anchor you will have to wait for some time until the glue “sets.”
- Mechanical. Bolts of this type are attached due to the expansion force when screwing the products into the concrete mass. Fasteners of this type are cheaper and are used much more often.
In turn, a mechanical anchor bolt can be:
Klinov
The wedge anchor (KA) is attached thanks to a special wedge located at the inner end of its sleeve. When hammered, the fastener expands the sleeve, thanks to which the element is securely fixed.
Also on sale are wedge-type anchor bolts with a nut, in which wedging is carried out thanks to a separate rod. After fixing the fastener, it is removed from the hole, and a special pin is installed in its place.
The anchor bolt with nut can be electrogalvanized (KA), acid-resistant (KAN) or hot-dip galvanized (KAK). Fasteners of this type also include a stainless steel screw anchor (RAR).
Hammerable
Driven-in anchors are characterized by a simple design - they do not have a wedge. Fastening is carried out thanks to the special edges of the sleeve, made of softer metal, which are deformed during the process of driving the sleeve.
To secure such an anchor, you do not need to measure the drilling location with millimeter precision; deviations in diameter and depth are also allowed.
This type of anchor is suitable for brickwork, natural stone and monolithic concrete surfaces.
Expandable
Expandable anchor (or “butterfly”) is used for thin-walled and sheet materials. The design of such a fastening element is distinguished by the presence of slots located in the middle of the sleeve. In the process of tightening the screw, its back part begins to move along the thread, and the sleeve is deformed, thereby forming peculiar petals that press the anchor (these elements are very clearly visible in the photo).
The main advantage of the “butterfly” is that the product can be dismantled at any time. To do this you don't have to do diamond cutting concrete and other labor-intensive work.
“Butterfly” is suitable for plasterboard, plastic and fiberboard. If there are in the wall metal elements(reinforcement), then before installing anchors in concrete, it is necessary to remove the reinforcing particles.
spacer
Expansion anchor bolts for concrete are considered the most popular due to their ease of use. When installing them, it is not necessary to strictly adhere to tolerances, depth and diameter of the hole. This device operates on the principle of collet expansion of the sleeve by screwing a cone-shaped sleeve into it.
There is also a double-expansion anchor for concrete, which contains two moving couplings at once. Thanks to this “structure” the product is characterized by increased fastening strength.
These types of anchors are used only for concrete and solid brick.
In addition, special products equipped with hooks and rings can be found on sale. The anchor loop is very convenient for installation lighting fixtures and communications.
Most often used for the production of fastening anchors stainless steel, coated with a layer of anti-corrosion compound. Products can be of different sizes.
Anchor bolt sizes
There is a standard marking that indicates the size of the anchors. For example, if the product bears the designation M10 12x100, then it is deciphered as follows:
- M10 (sometimes indicated without a letter) indicates that the bolt thread diameter is 10 mm.
- The number 12 is the diameter of the hole in mm that must be drilled to install the anchor.
- 100 is the length of the anchor bolt in mm.
For household purposes, products with sizes from M6 to M12 and a length of up to 160 mm are most often used. Longer bolts are used as specialized fasteners.
If we talk about the load that the anchor fasteners can withstand, then even the smallest anchor with a length of 18 mm can withstand about 800 kg. Typically this parameter is determined based on the following characteristics of the concrete anchor:
- leveling force – from 10.5 to 18.3 kN;
- bending moment – from 5.2 to 25.7 Nm;
- torque - from 10 to 40 Nm.
If product performance does not exceed these values, then they will reliably serve for a long time.
The service life and reliability of the fastening elements will also depend on how correctly the anchor bolts were installed in the foundation and any other surface.
Anchor installation technology
Let's take a closer look at how to fasten an anchor bolt in concrete surface. To do this you need to follow these steps:
- Calculate the length of the mounting bolt. To do this, evaluate the condition of the wall; if finishing material is applied to it, then the fastening element must be longer, since the plaster layer is too fragile and is not able to hold the bolt. Thus, if there is a layer on the wall finishing material 20 mm thick, then the length of the anchor fasteners must be at least 70 mm.
- Choose a drill that is 0.5 mm smaller than the diameter of the bolt (so that the sleeve enters the wall with force).
- Apply markings to the surface, taking into account the distance between the anchor bolts. At this stage, carefully measure everything, since in a situation of miscalculation, it will be difficult to remove the installed fasteners.
- Drill using a hammer drill (you can use impact drill) a hole in a wall or floor. It is best to use a special carbide tip for this. If you are drilling into a brick wall, it is better not to use impact equipment so as not to destroy the masonry.
- Clean the prepared hole from dust and cement particles. To do this, first remove large concrete residues with a brush, and then get rid of smaller particles using a vacuum cleaner or a can of compressed air.
- Hammer the sleeve into the hole. Do not apply strong blows, otherwise you may damage the fastener. If you cannot hammer into the product with a hammer, then you need to slightly widen the hole by going through it again with a drill.
- Screw the anchor pin into the sleeve and screw the nut onto it. When the nut reaches the sleeve, start tightening it with a special torque wrench (a screwdriver will not work). First, make 1-2 gentle turns, after which more force will be required, as the sleeve will begin to enter the sleeve.
- Pay attention to the packaging of the anchors, it should indicate maximum amount revolutions and the force with which the key must be operated.
- Do not tighten the bolts “all the way”, this will cause minimal damage to the surface, especially if you are using an anchor for aerated concrete or other light and porous concrete.
Sometimes it happens that the nut “sinks” into the plaster during installation. If you use a nut on a threaded rod, then you can safely continue installing the element until it completely “goes” into the wall. To fix the fastener, you simply need to use another nut, which can be screwed over the one that has “gone” into the wall.
In custody
Today there are fasteners on sale for the most different materials, so you can easily choose an anchor for hollow slabs, brick walls and a monolithic foundation. The main thing is to correctly calculate the depth to which you need to drive the bolts and get rid of the interfering pieces of reinforcement located in the wall.
Often in everyday life or construction it is necessary to secure any parts, workpieces, or mounting structures. There are a variety of fasteners for this; if the workpieces are wooden, then ordinary wood screws are used, and for brick or concrete special ones are used anchor bolts.
Various diameters and lengths
With their help you can attach quite heavy structures, for example a water heater, a children's swing to the ceiling, a sports wall, a satellite dish, etc.
The anchor bolt is a simple design: an internal bolt, a nut at the end and a body, there is plastic gasket to prevent moisture from getting inside.
In analysis
Operating principle of the anchor. It is a spacer; when you tighten the bolt clockwise, the nut at the end is pulled into the body, due to this the body expands, increasing in diameter and sits tightly in the wall.
How to fix an anchor bolt.
First you need to drill a hole in concrete (brick). The diameter of the hole must be exactly the same as the outer diameter of the bolt.
Next, insert the bolt through the hole in the workpiece, which we attach to the wall.
The most important thing is that there is no need to disassemble the anchor; it is inserted entirely as is. Many people try to take it apart piece by piece and then put it back in again. You can only disassemble the anchor with the nut, but only twist the nut, no more.
After the anchor is inserted into the wall, twist it clockwise. Fastening with an anchor is convenient, fast and, most importantly, very reliable.
Size range.
Typically, anchors are marked with, for example, the following dimensions: (8*6*60), (12*10*100), (16*12*110).
Let's figure out what these numbers mean.
1 digit – outer diameter of the anchor.
2nd digit – diameter of the internal bolt
3rd digit – total length
Based on this, you select the optimal fastener in terms of diameter and length, depending on the weight of the structure; the heavier, the thicker and longer the anchor. For example, for a TV, 8 mm is enough, for a children's swing, 12 mm or 16 mm in outer diameter.
For particularly critical structures, it is better to take a thicker and longer anchor.
Very often, to fasten heavy structures to concrete, people use dowels with self-tapping screws, which is not very reliable, or maybe they simply do not know about the existence of anchor bolts - reliable, strong and quick fasteners for concrete.
Main types.
1. Anchor bolt with washer (1 photo). The most commonly used type of fastener, a wide washer, allows you to securely press the structure to a wall or base.
With a nut at the end
Its advantage is that it allows you to attach heavy objects without any problems; you do not need to hold the object suspended for a long time while you thread the anchor through the hole in the object and insert it into drilled hole. Those. insert the anchor, hang the object, tighten the nut, and you get a collapsible anchor.
3. Anchor with hook or ring.
Used for tensioning ropes, cables. You can hang a chandelier on it.
4. L-shaped anchor. It has a 90 degree hook at the end. Very often water heaters are attached to it.
Fastening with various types anchors are characterized by specialists as connections that can provide reliable retention of heavy loads. After deepening into a pre-prepared hole, the worker, depending on the tasks at hand, chooses the best way to fasten the anchor bolt. After the assessment, when the selected surface areas are suitable for organizing a point that provides fastening of anchor devices, the point is arranged with subsequent fastening of the equipment.
The use of anchor supports is necessary when using a rope movement system during installation and construction work at height, fixing slings to position and hold the worker without slipping or jerking. The strength of the connection allows the use of anchor points and lines to ensure the installation of collective and individual protective equipment, making it possible to safely carry out installation work on products and maintenance of devices located at height.
Using a kit for fastening to anchor supports, it is possible to install the coupling on power transmission line supports and wind the free length of the optical cable onto the frame. This type of connection is used to ensure the safety of work performed at height according to the permit. To carry out such activities, a permit is required, issued by a labor protection specialist and endorsed officials from among the managers, and the work itself is carried out by a group of workers under the leadership of foremen and supervisors.
The most widely used are anchor bolts that have a spacer operating principle based on the expansion of the rear section of the sleeve when a cone-shaped sleeve is screwed into it. Among known species anchors, experts call driven, expanding, chemical, expansion and wedge structures. Each of them ensures reliable retention of the fastening part due to the use of the friction force between the contact surfaces of the bolt and the installation area, the thrust force, which ensures compensation of the effective stress by the resistance of the metal of the product. Increasing the diameter of the spacer sleeve when screwing a bolt into it ensures a reliable connection due to the combined action of thrust and friction forces.
Experts emphasize the importance of choosing the right type of anchor, based on studying the manufacturer’s documents that determine the specifics of each type of product. since the reliability of the system largely depends on building material, used at the bolt attachment point. Proper execution fastening is necessary to avoid destruction during operation of the parts that make up the connection, to ensure comfortable work in the support. Such a connection will ensure safety when working at heights, fastening heavy static (horizontal bars) and dynamic (diamond drilling rigs) structures.
Types of anchor fastening
As noted above, right choice the place where the anchor point of attachment is made plays important role in the process of ensuring worker safety. It is possible to assess when the selected areas are suitable for installing anchorage points by the load they can withstand; each of them must withstand a weight of at least 22 kN. To ensure reliable connection, the anchor point used to fasten the equipment can be connected to the load-bearing elements of the building, pre-assembled metal structures. After drilling the hole and installing the anchor, kits are used to secure the safety structures to the anchor supports. The standard kit used for anchor type fastening includes:
- 3 anchors;
- threaded rod;
- punch for making a recess;
- nuts that require the use of an open-end wrench.
Additionally, the kit used for fastening to anchor supports may include a washer and a punch to ensure wedging when using an anchor of the appropriate design. In addition, a kit for carrying out anchorage may include a larger number of bolts, but in this case the cost of one set increases. The kit providing fastening of security systems to anchor supports includes an anchor clamp, steel cable small size, wedges and bracket, providing the ability to mount up to 3 clamps.
Structurally, an anchor bolt with a nut is a stud with a thread on one side, with which the nut is screwed on, and the other end is made in the form of a spacer cone. When tightening the nut, the spacer-type bushing, on the side surfaces of which there are slots, expands, forming “petals” that ensure a reliable connection with the support surface.
Note! Before attaching anchor bolts, the concrete surface is drilled, and the drill, with the exception of cases of impact-type bolts, corresponds to the diameter of the anchor used.
Anchors used to fasten parts of geogrids are mounted around the perimeter of each of the mounted modules. The anchor for fastening the geogrid is installed according to a pre-approved diagram, so that the tension lines provided resemble a rectangle.
Manufacturers present high requirements to the quality of products, checking the strength of elements necessary to ensure safety, excluding their damage, breakage or failure. When using rope access systems, it is prohibited to use only one rope when ascending or descending planes, as well as when performing installation work. To provide safe operation flexible anchor lines, the correct answer when asked by the instructor about the specifics of use is the need to use limiters at the end to prevent the descent from passing the end of the rope. Permissible impacts are determined effective load in operating structures. In turn, workers receive a work permit by giving the correct answers after preliminary instruction.
Impact method
The use of this method involves the use of drive-in type anchors and is characterized by ease of installation and reliability of the resulting connection. However, the method has limitations regarding the possibility of using it exclusively when working with materials with high strength values, for example, concrete, solid brick or stone.
- Before attaching a drive-in anchor bolt, it is necessary to drill a hole whose diameter corresponds to the parameters of the bolt used.
- After this, it is necessary to clean the prepared hole from debris and dust.
- On next stage a hammer-type bolt is installed in the hole.
- Using a hammer and other tools, such as a bit or a special wedging structure, the striker is inserted into the conical hole. At the same time, the sliding part of the bolt opens, providing support against the walls of the prepared hole.
- At the last stage, the parts are fastened using a pin or bolt.
Expandable design
The design of the expansion bolt has the form of a rod cylindrical, in which there are 3-4 segments independent from each other. In the upper part, the segments are held by a ring; at the bottom there is a spring with high elasticity. Elements of this type are used for fastening massive structures into materials made of brick, rock, and concrete. When using fastenings to hold structures whose weight is below average, it is permissible to make connections into a brick (silicate type) wall, limestone and cellular concrete.
Before attaching the fastening anchor bolts, it is necessary to first mark and drill the hole before installing the fixing element. After this, a sleeve of the product is mounted into the wall; when a pin or bolt is screwed into it, the spacer element moves to the rear section of the fixture, thereby ensuring high pull-out strength of the connection.
An anchor bolt with a ring is a pin, at the end of which there is a ring and a threaded thread. When the pin is turned during tightening, the spacer element moves, ensuring that the segments diverge in opposite directions. A product of this type is used when it is necessary to permanently fasten structures of heavy or medium weight, for example, to stretch cables.
Wedge design
A wedge-shaped anchor is a pin, at one end of which there is a wedging coupling, which ensures strong installation of the product in stone, solid brick, and reinforced concrete. On the other side there is a thread, when moving the nut along which when tightening the structure, the coupling wedges. The device is used when installing mounted equipment, pipe and cable communications, load-bearing consoles and is used when it is necessary to ensure high fastening strength.
How to install an anchor bolt
Before attaching an anchor bolt with a nut, it is necessary to drill a hole, the diameter of which must be equal to the thread parameter. After cleaning the hole from dust, the anchor is installed in it, with the conical part directed inside the hole, the length of which is slightly greater than minimum depth for anchoring. Using a hammer, the anchor is inserted until the required installation depth is reached, after which the nut is tightened.
After ensuring the required tightening torque, which is best controlled using a torque wrench, the nut is unscrewed, a suspended structure (for example, a stand for diamond drilling) is installed on the stud, and the nut is tightened.
Chemical anchor, fastening with glue
Fastenings based on filling the inside of a metal rod embedded in the wall are used to provide strong connections in stone, brick, sandstone, shell rock, limestone, and cellular concrete. Such connections involve the use chemical anchors, for example the popular all-season type moment fastener CF900. A metal insert, which is a reinforcement rod, a threaded stud or a sleeve with a thread on the inner surface, goes deep into a prepared hole, the diameter of which exceeds the anchor parameter by 2 mm. After this, a capsule with glue based on polyester, polyurethane or acrylic resinous substances, a hardener and filler in the form of sand is inserted into the sleeve. Then the glass cylinder is destroyed and a metal rod is inserted into it and the binder is waited for setting.
Calculation of anchors
Performing a pull-out test on connections is often performed on site. Permissible load will depend on the base material, for example:
- When installing massive structures at height, the required tensile strength should be about 700 kg, which is why experts recommend using chemical types of anchors for such fastenings.
- When using concrete or brick as a base, the average load is about 350 kg, this value is sufficient for fastening medium and heavy structures.
- When using foamed concrete, the load it can withstand will be about 250 kg.
In addition to the calculation bearing capacity elements used, it should be ensured right moment tightening threaded connections. If the tightening is insufficient, there may be no frictional force in the connection; if the recommended values are exceeded, there will be a possibility of material destruction due to overpressure on the base.