Detailed explanation of the types, applications and design principles of spread anchors

Spread anchors are a type of fixing widely used in construction projects, mainly used to fix structural members such as columns, beams, trusses, wall panels, double T-plates, etc. They are designed to provide a strong anchoring effect through the expansion cone formed by the anchor foot in the concrete. There are various types of spread anchors, mainly including two hole anchors, spread erection anchors, unilateral erection anchors, and plate spread anchors. Click on the spread anchor to learn The following will introduce the types of these anchors and their performance characteristics in practical applications in detail.

Types of Spread Anchors

Two Hole Anchors

The two hole anchor is a basic type of spread anchor, usually used in applications that require strong fixing force. It is characterized by providing higher pull-out resistance through two anchor holes, suitable for fixing high-load components.

Spread Erection Anchors

Spread Erection Anchors are mainly used for vertically installed components. They are designed to provide strong anchoring force in the vertical direction. This anchor is usually used to fix columns and vertical wall panels to ensure that the components remain stable during construction.

Unilateral Erection Anchors

Unilateral Erection Anchors are similar to spread erection anchors, but their design is more suitable for applications that require fixing from one side. They are often used to install components close to the edge, providing a convenient installation method while ensuring stability.

Plate Spread Anchors

Plate spread anchors are usually used to fix large flat plate components, such as double T plates and large wall panels. Its flat plate design provides a larger contact area, thereby dispersing stress and improving the anchoring effect.

Anchoring Principle

The anchoring effect of the spread anchor in concrete is mainly achieved by the expansion cone formed by its anchor foot in the concrete. The anchoring resistance depends on several factors:

Concrete strength (fck):

The strength of concrete directly affects the anchoring effect. Higher concrete strength can provide a stronger anchoring force.

Length of the spread anchor (L):

The longer the anchoring length, the better the anchoring effect, because the larger the expansion cone formed by the anchor foot in the concrete.

Distance from the concrete edge (TN):

The farther the anchor position is from the concrete edge, the better the anchoring effect, because the influence of the edge effect on the anchoring force is reduced.

Distance between anchors (TN):

The larger the distance between anchors, the better the anchoring effect, because the expansion cones of adjacent anchors do not interfere with each other.

Influence of expansion cone

The larger the expansion cone formed by the anchor foot in the concrete, the stronger the anchoring resistance. The anchoring force reaches the maximum value when the distance between the two anchors is greater than 3.5 times the anchoring length and the distance from the concrete edge is greater than 1.75 times the anchoring length. The size and shape of the expansion cone directly affect the anchoring effect. Reasonable design and installation can maximize the performance of the spread anchor.

Design and Installation

During the design and installation of the expansion anchor, the above factors need to be fully considered to ensure the best anchoring effect. The specific design steps are as follows:

Determine the anchoring requirements:

Determine the required anchoring force according to the type of structural member and the load requirements.

Select the anchor type:

Select the appropriate expansion anchor type according to the anchoring requirements and the installation environment.

Calculate the anchoring length:

Calculate the anchoring length of the expansion anchor according to the concrete strength and the required anchoring force.

Determine the anchor spacing and margins:

Ensure that the distance between anchors and from the anchor to the concrete edge meets the design requirements to avoid mutual interference and edge effects of the anchoring force.

Installation:

Install according to the design requirements to ensure that the anchor is fully embedded in the concrete to form an effective expansion cone.

Use Cases

Application in High-Rise Buildings

In high-rise buildings, expansion anchors are often used to fix precast concrete panels and steel structural members. For example, when fixing precast concrete wall panels, plate-type expansion anchors are usually used to provide sufficient anchoring force and stability. By properly designing the anchor length and anchor spacing, it is possible to ensure that the wall panels remain stable when subjected to wind loads and seismic forces.

Application in bridge engineering

In bridge engineering, expansion anchors are often used to fix major load-bearing components such as beams and columns. Expansion vertical anchors and single-sided vertical anchors are particularly common in such applications because they can provide strong anchoring force in the vertical direction to ensure the safety and stability of the bridge structure.

Application in industrial buildings

In industrial buildings, expansion anchors are often used to fix large equipment foundations and steel structure frames. Two-hole anchors are often used to fix high-load equipment due to their strong pull-out resistance to ensure that the equipment does not move during operation.

As an important building fixing, the design and application of expansion anchors are of great significance to the safety and stability of building structures. By reasonably selecting the anchor type, calculating the anchor length, and determining the anchor spacing and margins, the anchoring effect of the expansion anchor can be maximized to ensure the safety and reliability of the building structure. In practical applications, scientific design and reasonable installation should be carried out according to specific engineering requirements and site conditions to ensure the best performance of the expansion anchor.