(3) Ground anchor bolt

Anchor bolts, also known as anchor bolts, anchor screws, anchor wires, etc., are components used to connect steel structure column bases with concrete foundations. Generally made of Q235 and Q345 round steel.

Different types of anchor bolts (with a diameter greater than 24mm, anchor plates should be used)

During installation, the anchor bolt group is fixed by a steel frame and installed together with the tied steel cage. Then, concrete is poured, and the bolt head should be exposed to the concrete surface for a certain length. After the concrete reaches a certain strength, install the steel column base, and finally perform secondary grouting at the bottom of the column.

Picture steel frame fixed anchor bolt group

Schematic diagram of anchor bolt in the picture

Picture of steel structure column base before secondary grouting (packaged with rubber sleeve to protect anchor bolt top from threading)

(4) Chemical anchor bolt

Chemical anchor bolt is a new type of fastening material composed of chemical agents and metal rods. Used to install connectors for other structures on existing concrete structures. It can be used for the installation of post embedded parts in various steel structures, curtain walls, marble dry hanging construction, as well as for equipment installation, highway and bridge guardrail installation, building reinforcement and renovation, and other occasions.

The screw and agent of the chemical anchor bolt in the picture

Chemical anchor bolt is a new type of anchor bolt that emerged after expansion anchor bolt. It is a composite component that is fixed to the fixed part by a specially made chemical adhesive and screw bonding in the drilled hole of the concrete substrate to achieve anchoring of the fixed part. Due to the high pull-out bearing capacity of chemical anchor bolts, they can replace embedded anchor bars. However, in construction sites where steel structure embedded parts are forgotten to be installed but concrete has already been poured, chemical anchor bolt embedded parts are added later to remedy the situation.

The construction steps of chemical anchor bolts are as follows:

1) According to engineering design requirements, holes should be drilled at corresponding positions in the substrate (such as concrete), and the aperture, depth, and bolt diameter should be determined by professional technicians or on-site tests.

2) Drill holes using impact drills or water drills.

3) Use a dedicated air cylinder, brush, or compressed air machine to clean the dust in the borehole. It is recommended to repeat the process no less than 3 times, and there should be no dust or visible water inside the borehole.

4) Ensure that the bolt surface is clean, dry, and free of oil stains.

5) Confirm that the glass tube anchoring package has no abnormal phenomena such as appearance damage or solidification of chemicals, and place its round head outward into the anchoring hole and push it to the bottom of the hole.

6) Use an electric drill and specialized installation fixture to forcefully rotate and insert the screw until it reaches the bottom of the hole, without using impact methods.

7) When it is screwed to the hole bottom or the marked position on the bolt, stop the rotation immediately, remove the installation fixture, and avoid disturbance after the gel is completely cured. Overtime rotation causes loss of adhesive and affects anchoring force. (The rotation time should not exceed 30 seconds, the speed should not be lower than 300 revolutions per minute, not greater than 750 revolutions per minute, the bolt pushing speed is about 2cm/second, and impact method is not allowed)

(5) Expansion bolt

The function of expansion bolts is the same as that of chemical anchor bolts, used for anchoring components with lower stress.

Expansion bolts of different specifications in the picture

Expansion bolts shall not be used in areas where concrete structures have cracks or are prone to cracking. At the same time, the expansion bolts used in the design of the main load-bearing structures, important pipelines, and high-speed operation, as well as those that can withstand impact loads and vibrations, should be selected according to the calculated design tensile strength and design shear strength, using a one level larger specification model.

4. Requirements for arrangement and construction of bolts

The arrangement of bolts is divided into two types: parallel and staggered:

Parallel - Simple, neat, and compact. The connecting plate used has a small size, but the cross-section of the component is greatly weakened;

Misalignment - The arrangement is not compact, and the size of the connecting plate used is large, but the cross-sectional weakening of the component is small.

Force requirements

Vertical force direction: In order to prevent the stress concentration of bolts from affecting each other and reducing the bearing capacity due to excessive weakening of the section, the edge distance and end distance of bolts cannot be too small;

Direction of force application: In order to prevent the plate from being pulled or cut, the end distance cannot be too small;

For compression members: To prevent bulging of the connecting plates, the center distance should not be too large.

Construction requirements

The edge and center distances of the bolts should not be too large to prevent the plates from not fitting tightly and moisture from entering and corroding the steel.

Construction requirements

In order to facilitate the tightening of nuts with a wrench, the bolt spacing should not be less than 3d0;

According to the above requirements, GB50017-2017 "Code for Design of Steel Structures" provides the allowable spacing and relevant design values for bolts.