framework
A scaffold is a temporary, generally reusable auxiliary structure made of mostly standardized scaffolding components made of wood and / or metal - steel or aluminum, which is used as a work platform, for fastening the formwork or as a protective device.
Uses
Working scaffolding
A work scaffold is used to carry out work on structural parts that are otherwise not accessible or difficult to access, such. B. plastering or work on the gutter. It must be strong enough to carry the people working on it, their equipment and the necessary work material. A work scaffold on which only a plumber has to install a gutter can therefore be designed in a lighter way than a scaffold from which natural stone work is carried out on the facade. Working scaffolds are described in DIN EN 12811: 2004.
Protective scaffolding
Protective scaffolding is not intended to be used to carry out work on the structure from there, but to secure workers and passers-by against falling or to protect them from falling components. The safety scaffold is such a protective structure. It provides fall protection for unsecured work surfaces such as walls that have not yet been raised. The roof safety scaffold is required to secure those working on the roof from falling deeper. The roof safety scaffold also serves to protect the people below against falling objects. In the case of areas over which work is carried out for a longer period of time, it may be necessary to arrange protective roofs on scaffolding in order to protect passers-by or workers from falling objects. Protective scaffolding is described in DIN 4420-1: 2004.
Falsework
Falsework is an auxiliary structure that is used to build arches and vaults. Falsework is called formwork in concrete construction and is used to support the empty formwork .
Support systems
Scaffolding is also differentiated according to its supporting system.
Stand scaffolding
In the case of a standing frame, the covering parts are attached to or on a frame component such as a wooden rod, a "ladder" or a frame that is fixed on the floor. This is the most commonly used support system.
Hanging scaffolding
A hanging scaffold is used when a standing scaffold cannot be placed. This is often the case on bridges or similar structures. The suspension is either on a separate bridge-like component, on a boom attached to or on a console.
Boom frame
In the case of a cantilever frame (Austrian term: scrap frame), beams are attached to the ceiling, on which the covering parts are then placed. It should be noted that the wall openings for the beams can only be closed after the scaffolding has been dismantled.
Console frame
In a bracket scaffold are consoles dowelled to the outer wall or in a steel cable suspended in or cast-in suspension loops. In contrast, standing scaffolding only needs a few attachment points or anchors that can be left in the facade in the form of nylon dowels or threaded sleeves .
Execution type
Pole frames
Pole frames are made of wooden or bamboo poles or simple metal tubes.
- Wooden pole frames are no longer common in Germany; they are still common in less developed countries. Wooden poles are or have been linked with hemp ropes or special scaffolding chains. The assembly requires extensive knowledge and skills in tying the frets and knots, which today only specialized scaffolders have, and assembly and dismantling are time-consuming. In Asia, bamboo scaffolding is still used today for scaffolding high-rise buildings, as they can withstand seismic vibrations for longer.
- A pipe coupling frame or steel pipe coupling frame consists mainly of smooth steel pipes and couplings that connect them. The scaffold couplings are made of cast material or sheet metal. In special structural situations, pole frame constructions may be necessary, often in connection with standard system scaffolding.
Ladder scaffolding
Ladder scaffolding has been around since the early 1950s. They are further developments of the wooden pole frames, in which two semicircular wooden poles perforated at regular intervals are connected in storeys with at least two rungs each. These so-called ladders are usually three floors high (one floor is two meters). Scaffolding planks were loosely placed on the rungs and handrail boards and stiffening diagonals (boards with holes and longitudinal slots) were screwed onto the scaffolding ladders. The workload compared to knotting was considerably reduced. In addition, there were far fewer sources of error when setting up the ladder scaffolding. This type of scaffolding was widespread until the early 1970s.
The use of wooden ladder scaffolding, however, for ergonomic reasons (they are difficult to set up because of the high weight and long lever arm) and for reasons of occupational safety is also seen rather historically. The use was inconvenient and inexpedient because of the restricted passage height of sometimes less than 1.50 meters and the narrow width of less than 60 centimeters. Due to the Ordinance on Industrial Safety and Health , resulting from the Occupational Safety and Health Act , together with the required risk assessment , they can no longer be used in the commercial sector in Germany.
System framework
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System scaffolds have numerous connection points to which system components can be attached and the scaffolds can be connected to one another.
- Frame scaffolds are system scaffolds with a short assembly time. In official German they are also called “scaffolding of a special type”; their static proof must be provided by the manufacturer through calculations and tests. After the test by the German Institute for Building Technology (DIBt), a temporary general building authority approval is granted. The system frame scaffolding is mainly used as working and protective scaffolding for the safe processing of facades or as protective scaffolding that prevents people or material from falling. There are six load classes and seven width classes. Depending on the work to be carried out, the client selects suitable classes.
- Modular scaffolds are system scaffolding in which prefabricated nodes are welded or otherwise attached to the posts at regular intervals of mostly 50 centimeters. These are used to attach other scaffolding components such as bars, diagonals, consoles or other manufacturer-specific components. Modular frames are a further development of the tubular steel coupling frames. They are mainly used as surface or space scaffolding, e.g. B. in industry as work and protective scaffolding. They are also divided into six load classes.
Parts of the scaffolding
Frames, floors, ladders
Scaffolds essentially consist of a few different individual parts. The vertical frames or module uprights stand on feet that are height-adjustable by means of a spindle , so that unevenness in the ground can be leveled out. Another frame can be attached to the top of a frame. Floors or scaffolding mats, which form the levels of the scaffolding, are placed on the frames. Modern system scaffolding clamp the shelves between the two frames in such a way that they cannot be lifted out accidentally or by wind suction. For a smooth assembly and dismantling it is important that all frames are exactly vertical and all scaffolding decks are horizontal.
The ascent and descent between the floors is made possible by the ladder corridors, which today usually consist of special scaffolding floors with an integrated flap and fixed, foldable ladder.
Securing the statics
The frames divert the loads into the subsoil, the scaffolding decks prevent individual frames from falling over and stiffen the scaffolding horizontally. On the outside of the scaffolding, diagonal struts are attached to prevent the entire scaffolding from falling over in the longitudinal direction. So that it does not fall over in the transverse direction, the scaffolding is usually anchored to the building with eyebolts in special scaffolding dowels .
Basically for every scaffolding - which does not correspond to any standard design - a proof of structural stability is required. In the case of system scaffolding, it can be replaced by type approval provided that it is used as intended.
Securing the outside
The vertical tubes of the frame are equipped with fastening options, on which railings are hung in two levels. At the bottom, a toe board must also be clamped between the supports so that you cannot slide under the railing if you slip and so that no material can fall down. The narrow or front sides are also secured by railings and end toe boards. One speaks here of a three-part side protection.
The outside can still be secured by protective nets, scaffolding tarpaulins or protective walls. Scaffolding tarpaulins can be attached to the scaffolding without flapping. They primarily serve to protect against the effects of the weather and in particular keep wind and rain or snow away from the scaffolding and the working people.
Composite pieces
Consoles and lattice girders
In order to adapt the scaffolding to the contours of a building, such as cantilevered cornices , brackets can be mounted on the supports, into which further planks can be hung. Larger distances, e.g. B. for entrances, can be bridged by installing lattice girders
The lowest frames are attached to system-independent lattice girders with couplings according to EN74. In the case of system-bound lattice girders, the respective manufacturer-specific system connections are used.
Elevators
Large scaffolding will be equipped with climbing elevators for the transport of materials and people.
Elevators for the transport of materials are only required from a scaffold height of 14 meters and a scaffold width of 10 meters, but can also make economic and ergonomic sense at lower heights.
A distinction is made between elevators:
- Construction hoists , which are generally only approved for transporting materials. However, there are also construction lifts approved for the transport of people. Much stricter regulations and lower lifting speeds then apply here.
- Transport platforms are only approved for transporting material and for assembly travel when setting up the platform.
- Mast-guided climbing work platforms are approved for the transport of materials as well as for the transport of people.
The respective anchor grid can be found in the instructions for assembly and use, which must be attached to each of the various lifting devices. This also contains the load-bearing capacity and the installation conditions.
Norms
The European standards EN 12810 and EN 12811 and their parts apply to work scaffolding throughout Europe. In Germany, a distinction is made in standardization between work and protective scaffolding. That is why there is also a separate “residual standard” DIN 4420-3-2006-01 for protective scaffolding in Germany with selected scaffolding types and their standard designs. For shoring, however, EN 12812: 2004 and EN 12813: 2004 apply across Europe (however, EN 12813 was not introduced by the building authorities in Germany and is not used in practice). Mobile scaffolding and rolling scaffolding are regulated by DIN 4422-1 and HD 1004: 1992. Further DIN standards and European standards regulate the requirements for individual scaffolding parts. DIN 18451 VOB / C General technical contract conditions for construction work. Scaffolding work usually forms the basis for execution and billing. In addition, the work safety regulations must be observed.
For the approval of scaffolding, the approval guidelines of the DIBt must also be observed. Here detailed requirements are made of the z. In some cases, they go well beyond the normative requirements that must be complied with for approval.
Health and safety regulations
In the occupational health and safety regulations, a distinction is made between:
- Creating the scaffolding
- Provision of a scaffolding
- Use of the scaffolding by employers
- accident
When erecting scaffolding , the scaffolding company must comply with the Occupational Safety and Health Act, its ordinance, here the Industrial Safety Ordinance, and the technical rules for operational safety TRBS 1203, 2121 Part 1 and 2, scaffolding access and leaning ladders. If the "technical rules for operational safety" are complied with, the employer can in this respect assert the presumption of compliance with the regulations of the industrial safety ordinance. According to TRBS 1203, the construction of the scaffolding may only be carried out by a qualified person and suitable and trained employees.
Provision of scaffolding means that it is constructed and labeled in accordance with DIN regulations, instructions for assembly and use or in whole or in part according to a strength and stability calculation and is made available for use in accordance with the Product Safety Act . The Equipment and Product Safety Act was replaced by the Product Safety Act on December 1, 2011. The creation of scaffolding work equipment, the safety of which depends on the assembly conditions, is regulated in § 10 "Testing of work equipment", § 11 "Recording of test results" and Appendix 2 No. 5.2 "Special regulations for the use of scaffolding".
In order for the employer to use the scaffolding, the employer must have the scaffolding checked by a qualified person before the employees step on it for the first time. If the employer or the employee is not a qualified person according to TRBS 1203, the employer must have this checked by an external qualified person. Before employees commence work, the employer must determine the hazards for the workplace by means of a documentary risk assessment and instruct the employees accordingly. Here he also has to inform the employees that conversion work on the scaffolding may only be carried out by a qualified person and suitable employees of the scaffolding contractor.
In the event of an accident , this means that the company whose employees have an accident on a work equipment “scaffolding” that has not been created in accordance with regulations is the first to be responsible and not the scaffolding company that created it. The reason is that the qualified person named by the employer, who can also be the employer himself, before using the scaffolding for the first time (TRBS 2121 Part 1, No. 5.3), check that the scaffolding is apparently free from defects and that it functions reliably, depending on the respective Use must convince. Since, according to TRBS 1203, high demands are placed on the qualified person in training, a high level of expertise is required for the "apparent examination".
Scaffolding contract
The scaffolding contract consists of the following services : delivery, assembly, provision, dismantling and removal. It has the special feature that the “work” does not become the property of the customer. While the erection and dismantling of the scaffolding qualifies as a work contract , the provision of the scaffolding fulfills the criteria of the rental contract . It is a mixed contract , so it is disputed which legal provisions apply to the scaffolding contract.
Manufacturer of system scaffolding (selection)
Further terms on the subject of scaffolding
In a figurative sense, scaffolding also refers to a plan , design or structure that fundamentally prepares an execution (framework of ideas, framework for the novel, etc.).
In general, a scaffold is also a climbing aid that should enable certain heights to be reached. There is this game Scaffolding and those for construction .
See also
literature
- Burkard Lotz: The scaffolding contract and the legal securities , BauR 2000, p. 1806 ff.
Individual evidence
- ↑ Duden | Scaffolding | Spelling, meaning, definition, synonyms, origin. In: duden.de. Retrieved April 16, 2019 .
Web links
- At the grave of a man who fell to death from a church tower , grave song with information on safe scaffolding by Pastor Michael von Jung , 1839
