How to select an anchor bolt?

Understanding the Basics of Anchor Bolts

Definition and Function of Anchor Bolts

Anchor bolts are fasteners designed to attach objects or structures to concrete, providing stability and preventing movement. They are typically used in construction projects such as buildings, bridges, and machinery installations. Anchor bolts transmit the load from the attached object to the concrete, ensuring structural integrity.

Yipeng supply professional and honest service.

Key Components of Anchor Bolts

An anchor bolt comprises several components, which collectively ensure its functionality and strength:

• Threaded Rod: The rod is an elongated metal shaft with threads on one end for attaching nuts and washers. It provides the means for securing the attached object to the anchor bolt.
• Anchor Body: The anchor body is the portion of the bolt embedded in the concrete, providing stability and load-bearing capacity. It is designed to distribute the load evenly and prevent any concentration of stress.
• Expansion Mechanism: Expansion anchors have expandable components that create a secure grip on the concrete when tightened. This mechanism ensures a tight and reliable connection, minimizing the risk of movement or failure.
• Washer and Nut: These components are used to secure the attached object to the anchor bolt, preventing loosening or movement. The washer distributes the load evenly, while the nut ensures a tight connection.

Different Types of Anchor Bolts

There are several types of anchor bolts available, each with specific characteristics and applications:

• Through Bolts: Through bolts, a staple in construction and DIY projects, offer robust fastening solutions for heavy-duty applications. Brands like Fischer, Timco, and JCP have established themselves as go-to options for quality through bolts. These bolts feature a design that allows them to pass completely through the materials being joined, providing exceptional strength and stability. Whether it&#;s securing structural elements or anchoring fixtures into concrete or masonry, through bolts offer reliability and peace of mind. Through Bolts are an insitu fixing which means that they can be secured whist the fixture is in place.
• Expansion Shield Anchor Bolts: These bolts expand when tightened, creating a secure connection to the concrete. They are commonly used in applications where a strong and reliable attachment is required. These come in two types: Loose Bolts (hexagon head type) and Projection Bolts (stud type).
• Sleeve Anchor Bolts: Sleeve anchors are versatile and ideal for light to medium loads. They consist of a cylindrical sleeve that expands when the bolt is tightened, providing a secure grip on the concrete.
• Chemical Anchor Stud Bolts: Chemical anchors use an adhesive to bond the bolt to the concrete, providing strength and resistance. They are commonly used in applications where traditional mechanical anchors are not suitable.

When selecting anchor bolts for a specific application, it is crucial to consider factors such as load requirements, environmental conditions, and the type of concrete being used. Proper installation and adherence to manufacturer guidelines are also essential to ensure the effectiveness and reliability of anchor bolts.

By understanding the basics of anchor bolts and their various types and components, you can make informed decisions when it comes to choosing the right fasteners for your construction projects. Whether you need to secure a structural element or attach equipment to a concrete surface, anchor bolts play a vital role in providing strength, stability, and peace of mind.

Selecting the Right Anchor Bolt for Your Project

Factors to Consider When Choosing Anchor Bolts

Choosing the correct anchor bolt for your project is crucial to ensure structural stability. There are several factors that you should carefully consider before making your selection:

1. Load Requirements: Determining the maximum load the anchor bolt will need to support is essential. You don&#;t want to underestimate the load requirements and end up with a bolt that cannot handle the intended weight. Take into account any potential future changes in load as well. We recommend consulting the manufacturers data sheets to ensure you meet the load requirements. The Fischer and Timco Websites list their product data sheets well.
2. Concrete Condition: Assessing the quality and strength of the concrete where the anchor will be installed is vital. The strength of the anchor bolt is directly influenced by the condition of the concrete. If the concrete is weak or deteriorating, it may not provide the necessary support for the anchor bolt.
3. Environmental Factors: Environmental conditions can significantly impact the performance of anchor bolts. Consider factors such as temperature, moisture, and chemical exposure. For example, if your project is in a coastal area with high humidity and saltwater exposure, you may need to choose anchor bolts that are resistant to corrosion.
4. Installation Method: It is crucial to select an anchor bolt type that is compatible with the installation method and tools available. Different anchor bolts require different installation techniques, such as drilling, adhesive bonding, or expansion. Ensure that you have the necessary equipment and expertise to install the chosen anchor bolts correctly.

By carefully considering these factors and avoiding common mistakes, you can ensure that you select the right anchor bolts for your project. Remember, the stability and safety of your structure depend on making the right choices from the beginning.

Installation Process of Anchor Bolts

Tools Required for Installation

Before starting the installation process, gather the necessary tools:

• Drill and Masonry Bits: Select a drill and appropriate masonry bits to create holes in the concrete.
• Hammer: A hammer is essential for driving the anchor bolt into the hole.
• Wrench or Socket Set: Use a wrench or socket set to tighten the nut on the threaded rod.
• Safety Equipment: Wear safety goggles, gloves, and a dust mask to protect yourself during installation.

Step-by-Step Guide to Installing Anchor Bolts

Follow these steps to ensure a secure installation of anchor bolts:

1. Mark the locations: Mark the desired locations where the anchor bolts will be installed.
2. Drill holes: Use a drill and masonry bit to create holes in the concrete according to the anchor bolt dimensions.
3. Clean the holes: Remove dust and debris from the drilled holes using a brush or compressed air.
4. Insert and align the anchor bolts: Insert the anchor bolts into the holes and ensure they are aligned correctly.
5. Tighten the nuts: Place the washer and nut on the threaded rod and use a wrench or socket set to tighten them until secure.
6. Verify stability: Test the stability of the anchor bolts to ensure a properly installed and secure connection.

Safety Measures and Precautions

Safety Equipment for Handling Anchor Bolts

When working with anchor bolts, prioritize safety by wearing appropriate protective equipment:

• Safety Goggles: Protect your eyes from flying debris during drilling and installation.
• Gloves: Wear gloves to prevent injuries while handling anchor bolts and tools.
• Dust Mask: Use a dust mask to avoid inhaling dust particles during drilling and cleaning.

Precautions to Take During Installation

Follow these precautions to ensure a safe and successful anchor bolt installation:

• Read Instructions: Carefully read and understand the manufacturer&#;s instructions before installation.
• Drilling Safety: Practice proper drilling techniques, such as maintaining a stable stance and applying consistent pressure.
• Secure Work Area: Clear the work area of obstacles and ensure proper lighting for a safe installation process.
• Inspect Anchors: Regularly inspect anchor bolts for signs of wear, damage, or loosening to prevent potential hazards.

Maintenance and Troubleshooting of Anchor Bolts

Regular Maintenance Practices

To ensure the long-term performance and durability of anchor bolts, follow these maintenance practices:

• Periodic Inspection: Regularly inspect anchor bolts for signs of corrosion, damage, or movement.
• Cleaning: Remove any debris or dirt accumulated around the anchor bolts to prevent interference with their functionality.
• Tightening: Check and tighten the nuts periodically to maintain the desired level of tightness.

Troubleshooting Common Issues

If you encounter any problems with anchor bolts, consider these common troubleshooting steps:

• Loosening Bolts: If bolts become loose, retighten them to the specified torque to ensure stability.
• Corrosion: Address any signs of corrosion by cleaning the bolts and applying appropriate protective measures.
• Damaged Threads: If the threaded rod or nut is damaged, replace the affected component to maintain integrity.

Conclusion

A comprehensive understanding of anchor bolts is crucial for successful construction projects. By grasping the basics, selecting the right anchor bolt, following proper installation techniques, and prioritizing safety and maintenance, you can ensure the reliability and durability of your structures. Remember to consult manufacturer guidelines and seek professional advice when necessary for optimal outcomes. With this comprehensive guide, you are well-equipped to embark on your anchor bolt endeavors.

Anchor bolts are used extensively in concrete, brick and block masonry and cavities to make structural attachments and connections. To date, a limited amount of information has been available to aid designers and users in the selection and design of anchor bolts in various types of substrates.

In new masonry construction, anchor bolts were commonly embedded in walls and columns to support beams, plates and ledgers. However, for flexibility and ease of construction, the use of post-installed anchors is increasing.

Post-installed anchor bolt systems

In prefabricated panel construction, anchor bolts are used to facilitate connections to the structural frame.

Renovation and rehabilitation of existing masonry structures usually require that anchor bolts be used to attach stair risers, elevator tracks and various frame assemblages for equipment installation.

This is only a fraction of the possible uses of anchor bolts in masonry construction and with the increase of new, innovative architectural masonry designs, the uses of anchor bolts in masonry construction are likely to increase.

Anchors can be divided into two generic categories: Expansion-type anchors and Adhesive or Chemical-type anchors.

Expansion Anchors

(a) Torque-controlled expansion anchors

Sleeve anchors develop their strength by the expansion of a cylindrical metal sleeve or shield into the base material as the bolt is tightened.

The expansion of the sleeve along the length of the anchor provides a larger bearing surface than the wedge anchor, and is recommended for use in brick masonry

Wedge anchors develop their hold by means of a wedge or wedges that are forced into the base material when the bolt is tightened.

The wedges create large point bearing stresses within the hole

Drop in Anchors are produced to allow shallow embedment depths and are expanded or set by an impact setting tool.

These are extremely suitable for installations into roof slabs. As the combination of shallow embedment and high stresses imparted by the expansion tend to cause cracking or splitting in masonry, they are not recommended for use in brick.

View our range of Concrete Anchors.

(b) Concrete screw

Concrete screws are screwed into pre-drilled holes by a special screwdriver &#; TORX DRIVE

The threads will cut into the concrete and create mechanical interlock between screw and concrete. This is an expansion free fixing.

View our range of Concrete Screws.

(c) Nylon based Anchors and Fixings

Wallplugs &#; Nylon wallplugs are placed in pre-drilled holes and screws are tightened into the plug creating the expansion.

These are available in many sizes and are very versatile useful for Brick, Block and concrete. Used for light loads.

Nylon Frame Fixings &#; A hole is drilled through the frame and into the masonry. The whole fixing is inserted through the frame into the masonry and the screw tightened.

These fixings are available in various head styles and plug designs to make them suitable for multiple applications in Brick, Block, Concrete, Aerated concrete, hollow bricks etc.

Suitable for fixing of facades, doors, windows, gates, cable trays, metal bracket etc.

View our range of Nylon Anchors and Fixings.

(d) CAVITY Fixings

These are used where objects need to be fixed onto plasterboard and other wall and ceiling cavities.

Expandet Rosett® is the strongest fastening solution in plasterboards, gypsum fibre boards, chipboards, and other cavity walls.

No special Tools are required.

Designed for heavy loads.

PLASTERPLUG Nylon Cavity Anchor

Used with screw is effective in most of the quick and light solutions in both 1 and 2 layer of plasterboard or other materials as chipboards, gypsum fiber boards and other walls with cavities.

This is a very popular design.

JET-Drive Metal anchor

This can be used without a predrill in most cases making it a fast and easy fixing.

Useful for light fixings without the mess of drilling.

Metal Cavity Anchor

Suitable for fixing cable trays, brackets, piping, and boards, etc .

Can be used with all metric threaded screws in plasterboards with cavity. Installation with special installing tool.

Spring Toggle Anchor

Extremely useful for fixing or hanging objects on a false ceiling.

Suitable for light duty fixings in ceilings and provides the possibility for bridging thick walls.

Especially suitable for fixing of suspended ceilings, brackets, cable trays, pipings etc.

View our range of Cavity Fixings.

Adhesive Anchors

Instead of the anchor holding itself against the surface, a chemical resin cures around the anchor and keeps it held in place.

Read more on our page for Chemical Anchors.

When to use Chemical Resin Anchors   

If you need to fix something close to the edge of a brick or stone because you intend to hang a gate or add a small fixing, anchors that expand can cause strength-ruining splits and cracks in the masonry. If the structure is subject to dynamic loads, vibration or wind, then chemical anchoring is preferable over mechanical anchoring.

Using anchors and fixings is all about getting the most secure fitting possible and sometimes the only way to ensure the surface stays intact is to using chemical resin.

Because it doesn&#;t expand or risk splitting/cracking, chemical resin anchors can also be used in weaker masonry that might crumble under the expansion of sleeve anchors and screw threads.

There are lots of benefits of using chemical resin anchors as they are more than capable of holding massive loads and their application can be fairly quick. However, correct preparation for fitting chemical resin anchors is essential.

How to use Chemical Resin Anchors

To use chemical resin and anchors together, ensure that you make an appropriate hole as recommended by the manufacturer&#;s catalogue in terms of diameter, depth and spacing.

If your drilled holes are likely to have voids (frequent in hollow blocks or bricks), you&#;ll need resin injection anchor sleeves to control the flow of resin and provide a secure fix to the substrate.

• Remove any loose material from the hole to get the best hold against a debris-free surface. Use a resin hole brush to do this.
• Also use a tube to blow air into the hole to get rid of more debris.
• Using an applicator gun, inject the resin into the hole.

It is important to make sure it&#;s mixing properly before you inject it into the holes. It&#;s advised to let some out first to allow it to mix.

Always ensure that the nozzle width and length are correct, and make sure to slowly withdraw the nozzle, so trapped air pockets don&#;t happen.

For deeper holes use a resin nozzle extension tube on the end of a mixer nozzle.

• In general filling about 70% of the hole will suffice to get complete coverage.
• As you push the stud in the hole, twist it a few times to break any air bubbles up. It also pushes the resin into any voids in the hole.

If the stud keeps pushing itself back out it may need a few more twists. All the threads should have an even covering.

• Once all the studs are in, you&#;ll have to leave them alone. How long this takes will depend on the brand of resin as well as the temperature. Resin tubes will have a guide on the label: a gel time and full cure time. Don&#;t load the studs until the full cure time.

The adhesive bond strength is reduced at elevated temperatures and may also be adversely affected by some chemicals.

ANCHOR BOLT DESIGN

Anchor bolts are used as a means of tying structural elements together in construction and therefore, provide continuity in the overall structure. In virtually all applications, anchor bolts are required to resist a combination of tension and shear loads acting simultaneously due to combinations of imposed dead loads, live loads, wind loads, seismic loads, thermal loads and impact loads. For this reason, and also to insure safety, anchor bolt details should receive the same design considerations as would any other structural connection.

This very useful free anchor design application can be downloaded from the below link.

Expandet Calculation Program

Considerations for Brick Masonry

There are several considerations that should be examined when contemplating the use of expansion-type anchors in brick masonry. These are:

1) Expansion anchors should not be used to resist vibratory loads. Vibratory loads tend to loosen expansion anchors.

2) Specific torques are required to set expansion anchors. Excessive torque can reduce anchor strength or may lead to failure as excessive torque is applied.

3) Expansion anchors require solid, hard embedment material to develop their maximum capacities. Some brick construction may not provide a good embedment material due to voids formed by brick cores and partially filled mortar joints.

Considerations for Torque controlled anchors

Expansion anchors must be torqued per the values provided in the Manufacturer&#;s Printed Installation Instructions (MPII) to properly expand the wedges and clamp the fixture. Under-torquing results in under-expansion of the wedges, which reduces the amount of clamping developed. Once pre-load/clamping is removed from an under-torqued expansion anchor subjected to tensile loading, the anchor will displace, resulting in follow-up wedge expansion and lift-off of the fixture.