Mechanical anchors are a solution that have been used for decades. During that time they have become an indispensable element of fastening in residential, engineering and industrial construction. Here Wiktor Paradny, global market development manager at Klimas Wkręt-met, takes a look back at the evolution and design changes over 100 years, which have brought forward the mechanical anchors of the today’s industry.
The task of mechanical anchors is to transfer loads from the fixture to the base material – usually concrete or masonry. Anchor design has changed over time, with the development of technology, as well as more stringent standards and increasing requirements of engineers and designers. To respond to the changing requirements of the market, this fastening system had to evolve regularly, resulting in the truly wide range of mechanical anchors that can be seen today – from the simplest expansion solutions to advanced seismic and smart anchor systems, combining mechanics, advanced technologies and providing online monitoring capabilities.
However, these advancements also prove that fasteners bearing such heavy loads and, ultimately, responsibility, should be of really high-quality, as well as meet the aforementioned standards and be legitimised by certifications. Only then can the security of the fastening and, consequently, the durability and safety of the construction, be assured. That’s why today, Klimas provides a large selection of steel anchors for concrete and ensures fast and trouble-free installation, which can be found in nearly 70 countries around the world.
Mechanical anchors: Definition and application
To begin with, it is worth explaining what is meant by a mechanical anchor. This working principle of this fastening element is based on friction forces arising between the fastener and base material, achieved thanks to expansion, wedging or a combination of these mechanisms. Thanks to their properties, mechanical anchors have been utilised in structural applications such as beams, columns of steel structures, as well as non-structural fastening applications, such as façades, balcony railings, self-supporting steel structures or in installation systems, as well as the installation of many surrounding elements.
The first expansion anchors appeared in the 1920s and 1930s. At that time their construction was uncomplicated; they consisted of steel pins with a simple spreading mechanism. At the time, what convinced designers to choose this type of fastening was the quick installation of the anchor and the lack of need to glue the parts. Unfortunately, the first anchors also had quite a few disadvantages, among which the most troublesome were limited load-bearing capacity, susceptibility to installation errors, as well as a lack of resistance to vibration and dynamic loads.
The solution itself, despite its still numerous imperfections, found recognition among designers and engineers. Subsequent decades thus meant further improvements and work on technologies. From the 1950s to the 1970s, one can speak of two breakthroughs. First, steel sleeves and improved expansion mechanisms appeared, and second, research began on the behaviour of anchors under cyclic loads.
In the 1980s and 1990s, when the world credited the rapid development of prefabricated structures, the bolt anchor industry also developed. For the first time, there was a need to implement testing standards, such as the American ICC and ASTM standards. The development of computer science and computer technology also led to experiments with simulations in anchor design.
The last two decades have seen some organising and standardisation of requirements for this type of construction fastening (see timeline above). In the late 1990s and early 2000s, European requirements were unified and grouped in key standards: ETAG – guideline for European Technical Approval; TR – Technical Report for design metal anchors for use in concrete; and CEN/TS design of fastenings for use in concrete.
In 2013, after the introduction of the new EU Construction Products Directive and the introduction of the Construction Products Regulation (CPR), there was another change – the ETAG guidelines were replaced by today’s valid EAD guidelines, and in 2018 TR and CEN were included in a single design standard, valid today, namely Eurocode 2 EN 1992-4:2018. All these changes led to the unification of testing of anchors for implementation as a construction product in the EU, as well as the standardisation of the design standard for the use of anchors in concrete in a single valid document.
Today, construction fastening is a highly developed technological field and this huge progression has not passed the anchors themselves. Nowadays you can talk about different types of anchors, among which there are sleeve anchors, screw anchors and wedge anchors, which give even better control over the anchorage. Segmented multi-element anchors are fasteners designed for heavy loads.
The entire family of mechanical anchors must resist static, quasi-static forces, seismic loads, the effects of high temperatures in the event of a fire R30 – 240, as well as the unfavourable conditions of external wet or chemically aggressive environments defined in corrosivity classes, such as C4-C5 according to ISO. Modern anchors are formed from stainless steel, are durable and strong, showing increased resistance to environmental conditions and even chemicals.
The development of mechanical anchors reflects changes in the approach to safety engineering, durability and workmanship. Today, designers no longer have to consider only the load capacity of the anchor, but also environmental conditions, seismic influence, removability and documentation requirements. Strict adherence to ETA documentation and integration with the digital design model (BIM) is becoming crucial.
Klimas anchor family
Klimas’ wide range of anchors includes anchors for non-cracked concrete with ETA, developed in accordance with EAD 330232-01-0601, in either the LE-ZN galvanised version or the LE-DNZ zinc flake version. These anchors are dedicated for professionals, but also for basic applications.
Another range is Klimas’ anchors for cracked concrete developed in accordance with EAD 330232-01-0601, which is available in three versions – the LE-ZNA4 galvanised anchor for internal applications in both zones of concrete; the LE-DA4 anchor with zinc flake SQ ceramic coating for external applications for installation of temporary elements; as well as the LE-A4 stainless steel anchor, for wet internal and external applications according to corrosivity class C4.
Klimas also aims to educate its customers about correct and safe installation, especially in the case of anchors, providing its Klimas DesignFiX software, which makes it quick and easy to determine all the
necessary parameters to properly design fastenings for use in concrete, according to Eurocode 2 EN:1992-4:2018.
Having spent a decade in the fastener industry experiencing every facet – from steel mills, fastener manufacturers, wholesalers, distributors, as well as machinery builders and plating + coating companies, Claire has developed an in-depth knowledge of all things fasteners.
Alongside visiting numerous companies, exhibitions and conferences around the world, Claire has also interviewed high profile figures – focusing on key topics impacting the sector and making sure readers stay up to date with the latest developments within the industry.
