In connection with the intensive development of monolithic-frame construction of high-rise buildings, hydroelectric power stations, bridges, nuclear power plants, the problem of joining reinforcing bars during construction work has become more acute. Multi-storey buildings and complex reinforced concrete structures, especially those located in areas with high seismic hazard, are currently being built from monolithic reinforced concrete, which requires proper and high-quality reinforcement knitting. It is the reinforcement of conventional concrete that provides structural strength to reinforced concrete structures.
Most recently, reinforcement was joined by welding or overlapping knitting wire. Today, on the territory of our country, for joining rebars, the main inexpensive and proven method is the connection on the couplings. The use of the coupling system consists in replacing the fragmentary joints of the knitting of the pins with the coupling joints of the reinforcement. This technique eliminates any damage from mechanical stress and is actively used in all areas of construction.
Application
Strong metal skeleton of a building made ofconcrete is necessary for the stable resistance of the structure to bending loads. The widely used methods of tying reinforcement with wire or by welding are laborious, complex, inefficient and expensive.
The connection of the reinforcement with a coupling is a stronger fixation of the two ends of the rods in a hollow metal cylinder in a certain way. The diameter of the reinforcing coupling is identical to the size of the incoming rod, the wall thickness is 2–5 mm, and its length varies from 7 to 20 cm. The main task of the coupling element is to securely fix inside and not loosen during operation. Today, hardware manufacturers offer a huge selection of couplings for fittings of any kind, made from quality high grade carbon steel.
This connection of reinforcement allows you to easily and simply connect two pins of the structure located in the same direction. That is, to carry out their butt joint end-to-end. This assembly is not efficient by wire tying and was previously done by a combination of welding and wire tying. The use of coupling fittings significantly reduces the level of labor costs, the cost of building materials and increases the speed of erection of a strong and reliable reinforced concrete structure.
The use of mechanical docking makes it possible to quickly fix the connection of reinforcing bars. In about 7-10 minutes, the ends of the pins are threaded, centered and screwed with a torque wrenchcouplings. It also simplifies the quality control of the joints.
Views
Couplings connecting fittings are classified according to different criteria.
- Couplings with tapered internal threads allow connecting rebars with a diameter of 12 to 50 mm.
- If necessary, to fix the fittings already built into the structure, use crimp (threadless) connections. They fix the rods by applying special friction linings inside the integral pipe element.
- The screw pins are secured with two lock nuts. This compact connection is used when connecting pins bearing a high load.
Sleeve connections are divided according to the diameter of the pins:
- The bars with the appropriate diameter are connected with a standard fastener.
- Rods with different section sizes are fixed with transition joints.
- In some cases, combined reinforcement reinforcement is used.
Sequence of actions for crimping connection
- Crimp elements are installed on the reinforcing bars at the docking point.
- Coupling is pressurized with a hydraulic tool.
- Visually checks build quality.
- Comprehensive check of the entire assembled structure.
If special crimping devices are used for mechanized joining, a strong fixation of the joints of coupling fittings for a long time is guaranteed.
Docking couplings are made from pipes with a small diameter corresponding to the dimensions of the reinforcing bars. For tightening with a key, the upper surface has the form of a hexagon. An inch thread is cut inside with a minimum pitch. The use of pipes with thick walls allows you to cut the coils of the required depth and ensure the strength of the connection. Coupling fittings are considered by experts to be the ideal solution for overlapping pins.
Assembly steps for longitudinal reinforcing pins with threaded couplings
- Couplings of appropriate sizes are being purchased and equipment is being prepared.
- The ends of the bars are threaded.
- Armature is installed in working position.
- Coupling is screwed on from one end.
- The second end is wound on.
- The knot is tightened to the extreme positions.
- Checking build quality.
To prevent problems with the state of the frame in the future, it is necessary to tighten the reinforcing knots with high quality and special keys.
Reinforcement connected by the coupling method forms a very strong connection. For such an assembly, there is no need to hire expensive specialists. It is enough to simply connect the prepared ends of the pins and secure with the appropriate metal cylinders.
Benefits
- Ability to connect rods at any angle.
- Special connectors increase assembly intensity.
- Identical connectors guaranteequality docking process.
- Economical use of reinforcing pins.
- Connection blocks can be used without restrictions.
- A simplified visual method for controlling the quality of joints.
- Regardless of the mass of concrete, the reinforcement cage remains intact.
- No need to hire qualified welders saves financial resources.
- Strength is distributed evenly along the entire length of the pin.
- Features of the equipment used reduce construction time.
- Threading is carried out by universal devices by rolling or stamping.
Installation of coupling fittings greatly simplifies and speeds up the process of erecting monolithic buildings. Practice proves that a rod tens of meters long, assembled with coupling fasteners, is not inferior in reliability and strength to a solid (not divided into segments) rod.
Coupling pipe fittings
Today, the building materials market offers a wide selection of pipeline fittings from different materials: time-tested, strong and durable cast iron, steel and brass less resistant to mechanical damage. Pipe fittings made of alloys of aluminum, nickel and titanium are less popular. Lightness, plasticity, low price are distinguished by polymer reinforcement. Faucets and valves made of porcelain, ceramics and glass can boast of resistance to any chemicals.
Choosing locking elements of the couplingfittings for the pipeline, it is recommended to focus on the material of manufacture of pipes. With similar material, many indicators coincide:
- The chemical composition of the liquid.
- Galvanic neutrality of all pipeline elements.
- Resistant to mechanical damage.
- Thermal identity.
Manual coupling fittings
A handwheel or handle mounted on a valve stem bushing, valve stem, drive head shaft, or built-in motor shaft is commonly referred to as a hand drive.
Manual drive moves the valve gate. Such systems are installed in places convenient for maintenance.
Remote manual actuators are more often used, allowing control of valves with any diameter installed in inaccessible places.
