Currently, they are different types of mechanical anchors available. However, concrete undercut anchors are the strongest, and they can resist much higher loads compared to the mechanical expansion anchors. That is the reason why this type of anchors are often utilised in structures such as water treatment, nuclear power plants, and power industries where failure often leads to catastrophic consequences and human safety is of great importance.
In general, the strength and suitability of concrete anchors to resist the transfer of any action load from the area of application are always decisive. When it comes to concrete capacity, any fixing can only be as excellent as the base materials it’s fixing in to. But how mechanical anchors transfer the action load from the area of application has significant effects on the concrete capacity to resist any action or load.
How the Undercut Anchors Work
As the name suggests, mechanical expansion anchors perform their duties by expanding into pre-drilled holes into the concrete. The expansion leads to friction that provides the strength and resistance to the load or tensile action. When tensile action is greater, it increases the horizontal forces which are needed more. High expansion forces result in high stress or compression zones in concrete, which affects how the concrete expansion anchors can resist the action.
The undercut anchors work differently. They perform their duties by developing a positive key into a self-cut or a pre-cut void inside the available concrete. In most cases, they either create their void and key into it as in the case of Liebig Ultra-plus BLS anchor, or they open out into some pre-cut voids as in Liebig Ultra-plus. They don’t depend on friction and expansion, which means that they do not lead to high stress or compression zone.
As a result, they’re able to take advantage of the concrete floor anchor capacity, making them resist even higher tensile loads or action. In addition to the normal tensile action loads, the reduction of the compression stress zones and the mechanical interlock in concrete make the undercut anchors manage all the action loads that are created in seismic, dynamic and shock as well as other conditions with high impacts.
The Installation Process
The installation process differs depending on the type of undercut anchors being utilized. For a split drive concrete anchor or a self-undercut anchor like Liebig Super-plus BLS, there’s no need for the special tools. The anchor itself creates the undercut. When the BLS anchor expands into the predrilled holes, all the keys at the bottom of the resulting expansion shield lead to voids at a certain or predetermined depth inside the available concrete.
The keys then lock into the voids to provide much-needed resistance to tensile action or loads.