Construction Fixings

When handling high-levels of tension and shear force, a heavy-duty anchor is a requirement, but how can users ensure they are selecting the correct type of mechanical anchor to guarantee the safety and reliability of a structure? In this article, JCP Construction Fixings looks at how to select the appropriate heavy-duty anchor, detailing the various types available and their distinct characteristics.

Users must first consider the required mechanism when selecting an anchor. For instance, the JCP drop-in anchor is a good option if the given application requires a flush fit with the concrete surface. However, for installations that require a through fixing, JCP throughbolts offer a more suitable solution – and are available in seven different ranges. For higher loads, JCP heavy-duty expansion anchors are suitable as they come in various head types. Finally, for applications which don’t require expansion against the walls of a pre-drilled hole during installation, ankerbolts are most suitable. These fasteners use a self-tapping action to create a secure hold, with no expanding force transmitted to the base material, enabling the ankerbolts to be fixed closer to each other and the free edge.

The next consideration is assessing the base material and the environment where the anchor will be installed. This step is crucial, as not only does it determine the appropriate type of anchor, but it also guides the selection of material and finish based on the surrounding environment. For example, it is recommended not to use torque controlled expansion anchors and drop-in anchors into base materials other than concrete, whilst ankerbolts can be installed into solid masonry blocks due to the absence of an expanding mechanism. Concrete can also be classified as cracked or non-cracked, each requiring different levels of European Assessment for an approved anchor. 

In corrosive environments where long-term durability is essential, an A4 stainless steel heavy-duty anchor would be the recommended choice given this material’s natural resistance to harsher environments. In contrast, for an indoor environment, a BZP (Bright Zinc Plated) version would be sufficient. For applications where fire resistance is important, only anchors that have been tested for fire resistance data should be used – these include JCP ETA certified throughbolts, ankerbolts, socket bolts and heavy-duty anchors. In seismic zones, it’s important to use seismic rated anchors so that application failure is prevented. JCP ETA certified throughbolts or heavy-duty expansion anchors, which are tested for seismic loads of categories C1 and C2, are optimal solutions for such applications. 

Furthermore, it is also important to understand the load type and the magnitude of the acting loads. Acting loads can then be compared to the resistance performance data, available from testing of the anchors – typically larger diameters with deeper embedment offer a greater load-bearing capacity. The anchor length should be selected based on the thickness of the fixture being secured. JCP’s range of heavy-duty anchors accommodates a variety of applications, with sizes available from M6 – M24 and lengths ranging from 70mm – 262mm. 

Finally, users should never overlook the importance of proper installation. Many heavy-duty anchors require precise hole depth, diameter and torque to perform effectively. Drop-in anchors require the correct setting tool to ensure proper expansion when hammered, while throughbolts and heavy-duty expanding anchors are properly set when the correct torque is applied during tightening. If an anchor is not installed correctly, it can compromise the performance and potentially lead to failure.

To support the correct selection and installation of anchors, JCP provides detailed instructions and technical data for every product, available for immediate download online. As well as this, JCP offers a free anchor calculation program, which takes into account loading types, as well as spacing and edge distances, to help engineers and specifiers select the correct anchors.