How to use anchor bolts

Anchor bolts are items used to attach structural elements to concrete foundations. They resist tension and shear and hold the attached part to the concrete foundation firmly and securely. They are normally used to attach equipment and components to concrete foundations and walls. They can be easily used to prevent equipment from falling over or to protect against earthquakes, as they provide a firm anchorage with simple work. Let's take a look at the usage and features of each type of anchor bolt.

Different types of anchor bolts

Anchor bolts can be classified into several types depending on their role and mechanism.

Anchor bolt (standard)

This is the most basic anchor bolt. The bolt is attached to the reinforcing steel bar using a wire or other means, before placing the concrete. In many cases, if you want to install it in a more precise position, fixing it to rebar alone is not sufficient. Countermeasures for installation include fixing anchor bolts in holes drilled in the formwork and using positioning materials in combination.

When multiple anchor bolts are to be attached with high positioning accuracy, a method may be used in which bolts are inserted into steel with holes drilled at desired intervals in advance and welded to integrate the steel and bolts. The depth of embedment of the anchor bolts and the length of the expected protrusion must be carefully considered before pouring the concrete and allowing it to solidify.

打込みアンカーの例

Drive-in anchor

Unlike the standard anchor bolt, this type of anchor bolt is placed later into a concrete foundation or wall that has already solidified.

First, a hole of appropriate diameter and depth is drilled into the concrete using a hammer drill, etc., and chips and debris are removed using a blower. The anchor is then firmly inserted into the hole, and the lower part of the anchor expands hitting the core  and becoming firmly fixed into the hole. Drive-in anchors are available in male-threaded core-rod type and female-threaded body type.

Both types are characterized by the fact that the expansion part expands by hitting the area and is fixed in the concrete hole. They are widely used because they are safe for anyone to install and do not require skilled techniques.

Chemical anchors (adhesive anchors)

This is a type of anchor bolt contained in a capsule-type container, and uses a chemical reaction of adhesive to secure the anchor bolt to the foundation. It is also known as an adhesive anchor.

Basic installation is the same as for drive-in anchors and fastening anchors. The chemical anchor is inserted into the concrete hole after removing dust and debris inside.Then a full screw or deformed steel rod is driven into the hole to break the container containing the adhesive, which starts the chemical reaction to attach the concrete and the bolt.

ケミカルアンカーの例

Tightening anchor

This type of anchor bolt is similar in mechanism to a drive-in anchor and uses the tightening of a screw to secure the bolt to the concrete. To use this type of anchor bolt, a hole of the appropriate diameter and length is drilled in the concrete and chips are removed using a blower. The anchor bolt is then inserted into the hole and the nut is tightened to the specified torque value, which expands the internal sleeve and firmly secures the anchor bolt to the inner wall of the concrete hole.

締付けアンカーの例

Summary

Anchor bolts are useful items that can help securely attach structural parts into concrete foundations and walls. They are often used at construction sites because they are easy to install.