Connection technology (scaffolding)
In scaffolding, the connection technology includes all connection means that are used for the detachable connection of individual scaffolding parts. They differ depending on the scaffolding construction and ensure the basic cohesion of the supporting elements of a scaffolding . Since the vertical, diagonal and, in some cases, horizontal supporting structure of scaffolding nowadays mainly consists of pipes, pipe connecting elements are used almost exclusively . Standardized connecting elements can be used across all manufacturers. Other connecting parts are only intended for use in the manufacturer's system. Scaffold couplings consist mainly of (galvanized) cast steel or aluminum .
Assembly
The connection technology, such as couplings , pipe and plug connections , screw or clamp connections, is installed in the system scaffolding according to the so-called assembly logic . Behind this is a standardized procedure for setting up scaffolding, which prevents assembly errors. The size of the connecting elements is determined by the so-called slip . This occurs under load at the connection points of the scaffolding parts and must not exceed or fall below a certain tolerance range. If the slip is too great, the flow of forces in the entire construction is influenced, the scaffolding loses stability and the potential for danger is significantly increased.
Couplings
Couplings are mainly used as connecting parts in tubular steel and coupling frames . This type of scaffolding conceals facade scaffolding that has a maximum height of 20 to 30 m and is made of steel tubes. The connection principle of the coupling is that the steel pipes are connected by means of a screw cap or by wedging . The loads of the coupling connections are transmitted by friction . Since connection technology essentially determines operational and work safety , couplings must be produced in accordance with DIN EN 74 “Couplings, centering bolts and base plates for work scaffolding and shoring”. They are subject to a test mark by the manufacturer . Couplings that are manufactured outside of the standard must be tested and approved by the Deutsches Institut für Bautechnik . There is an embossing on each coupling element that provides information about the coupling class. Depending on the coupling type and class, a distinction is made between which load the coupling is approved for.
The inner half-shell diameter of the coupling corresponds to the outer diameter of the scaffolding tubes and is usually 48.3 mm for steel scaffolding .
Today, the couplings are mainly clamped using hammer head bolts and collar nuts. Wedge connections in which a wedge is hammered in as far as it will go with a 500 g hammer are used less frequently .
The nuts of the toggle locks usually have a wrench size of 19 or 22 mm and must be tightened with a torque of 50 Nm . With a key with a lever arm length of 25 cm, this means that a force of 20 kg must be applied to establish the connection in accordance with the standards.
In all cases, forces are transmitted through the friction between the pipe and the inner surface of the coupling.
Normal coupling (abbreviation RA)
Normal couplings are used when two pipes that cross at right angles are to be rigidly connected to each other. This is the case, for example, when crossbars are to be connected to stands. When connecting the pipes, make sure that the pipe ends protrude at least 4 cm beyond the coupling. The so-called "lower coupling" is used when larger loads have to be safely absorbed. The normal coupling is reinforced by a coupling placed underneath in order to increase the slip load of the connection. The prerequisites for a stable connection are that the couplings touch each other and only normal couplings of class BB are used.
Rotary couplings (abbreviation SW)
If the pipes in the coupling and steel framework intersect at a different angle than at right angles, rotary couplings are used. With this connection technique, pipe supports are connected using swivel bolts. It is only to be used for diagonal struts where normal couplings cannot be used. They can also be used to secure intermediate crossbars in position.
Butt couplings (abbreviation SF)
A butt coupling is used when a pipe is to be extended axially with another pipe. Butt couplings are usually used together with a centering bolt, also called a pipe connector, pushed into the pipe ends. A distinction is made between push-pull couplings and push-pull couplings. The former can transfer tensile forces as planned at the connection point, while the latter serve to secure connections that are primarily exposed to shear and pressure loads .
Other standardized coupling types
Parallel couplings (abbreviation PA) are used when scaffolding tubes running in parallel are to be connected to one another. This is the case, for example, with double stands.
Half-couplers are used if scaffolding tubes are to be connected to other scaffolding parts such as profiles, wooden components or sheet metal . Square timber couplings have plates or brackets with holes through which they can be screwed to square timber .
Suspended scaffold couplings are triple clamping devices that enable angle, double T and U profiles to be suspended.
If the scaffolding structure is to be transported on crane hooks, crane eyes are used.
For the connection of lattice girders to the structural uprights come girder couplings used. They are connected to a fixed bridge at a right angle.
Many other special couplings are not included in DIN EN 74, but are marked by the Deutsches Institut für Bautechnik : handrail coupling, anchor coupling, swivel coupling, tilt pin coupling, combination coupling, coupling with ring nut.
Pipe and plug connections
_03_ies.jpg)
Simple plug connections are primarily used for mobile high-speed scaffolding. The tubes are tapered at the top so that they can be connected to one another by simply plugging them together. Alternatively, the tubes have pins at the top . The mounting hole of the covering can also be placed on the tenon or taper. Self-locking plug connections are created by toggle pin connections. The scaffolding components are placed over the tilt pin. After moving the pin, the scaffolding connection is firmly locked.
Screw connections
A direct screw connection between scaffolding elements requires increased effort. Screw connections are primarily used in shoring construction where greater loads have to be absorbed.
Hook and claw connections
Hook and claw connections can be assembled quickly, but are usually not compatible between different manufacturers. They transmit tensile and compressive forces to diagonals and are used to hang connecting rods, decking parts or railings.
Beam clamps
Beam clamps can only absorb tensile forces to a limited extent. A non-positive connection is achieved through contact pressure and friction. Beam clamps are used to connect flat steel, rolled sections and frame parts to one another.
Module node connections
Modular frameworks are also known as system frameworks. The central connecting element is the module node connection, which is attached to the uprights of the scaffolding at regular intervals and enables up to 8 scaffolding components to be attached without the need for additional connecting fittings. Depending on the scaffolding construction, the ledgers must be attached at right angles, but in many cases the angle is variable.
literature
- Reiner Kübert: Scaffolding. Manual. Huss-Medien GmbH Verlag Bauwesen, Berlin, 2003.
Web links
Individual evidence
- ↑ Archived copy ( memento of the original dated December 24, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF file; 2.47 MB) “Construction” technical committee of the BGZ: BGR 167 - Scaffolding: tubular steel and coupling scaffolding. HVBG main association of commercial professional associations. April 2000 (as of June 28, 2011)
- ↑ http://www.geruestbau.org/normalkupplung-20111833 (June 28, 2011)
- ↑ Dipl.-Ing. Univ. Jochen Gebauer: Instructions for use - pipe-coupling connection "Not like this, please"! In: The scaffold builder. Trade magazine for scaffolding companies. 3/2010. Pp. 16-18
