The Benefits of Using anchor bolt installation

Mechanical loads (forces) applied to a structure or its components

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A structural load or structural action is a mechanical load (more generally a force) applied to structural elements.[1][2] A load causes stress, deformation, displacement or acceleration in a structure. Structural analysis, a discipline in engineering, analyzes the effects of loads on structures and structural elements. Excess load may cause structural failure, so this should be considered and controlled during the design of a structure. Particular mechanical structures&#;such as aircraft, satellites, rockets, space stations, ships, and submarines&#;are subject to their own particular structural loads and actions.[3] Engineers often evaluate structural loads based upon published regulations, contracts, or specifications. Accepted technical standards are used for acceptance testing and inspection.

Types

In civil engineering, specified loads are the best estimate of the actual loads a structure is expected to carry. These loads come in many different forms, such as people, equipment, vehicles, wind, rain, snow, earthquakes, the building materials themselves, etc. Specified loads also known as characteristic loads in many cases.

Buildings will be subject to loads from various sources. The principal ones can be classified as live loads (loads which are not always present in the structure), dead loads (loads which are permanent and immovable excepting redesign or renovation) and wind load, as described below. In some cases structures may be subject to other loads, such as those due to earthquakes or pressures from retained material. The expected maximum magnitude of each is referred to as the characteristic load.

Dead loads are static forces that are relatively constant for an extended time. They can be in tension or compression. The term can refer to a laboratory test method or to the normal usage of a material or structure.

Live loads are usually variable or moving loads. These can have a significant dynamic element and may involve considerations such as impact, momentum, vibration, slosh dynamics of fluids, etc.

An impact load is one whose time of application on a material is less than one-third of the natural period of vibration of that material.

Cyclic loads on a structure can lead to fatigue damage, cumulative damage, or failure. These loads can be repeated loadings on a structure or can be due to vibration.

Imposed loads are those associated with occupation and use of the building; their magnitude is less clearly defined and is generally related to the use of the building.

Loads on architectural and civil engineering structures

Structural loads are an important consideration in the design of buildings. Building codes require that structures be designed and built to safely resist all actions that they are likely to face during their service life, while remaining fit for use.[4] Minimum loads or actions are specified in these building codes for types of structures, geographic locations, usage and building materials.[5] Structural loads are split into categories by their originating cause. In terms of the actual load on a structure, there is no difference between dead or live loading, but the split occurs for use in safety calculations or ease of analysis on complex models.

To meet the requirement that design strength be higher than maximum loads, building codes prescribe that, for structural design, loads are increased by load factors. These load factors are, roughly, a ratio of the theoretical design strength to the maximum load expected in service. They are developed to help achieve the desired level of reliability of a structure[6] based on probabilistic studies that take into account the load's originating cause, recurrence, distribution, and static or dynamic nature.[7]

Dead load

The dead load includes loads that are relatively constant over time, including the weight of the structure itself, and immovable fixtures such as walls, plasterboard or carpet. The roof is also a dead load. Dead loads are also known as permanent or static loads. Building materials are not dead loads until constructed in permanent position.[8][9][10] IS875(part 1)- give unit weight of building materials, parts, components.

Live load

Live loads, or imposed loads, are temporary, of short duration, or a moving load. These dynamic loads may involve considerations such as impact, momentum, vibration, slosh dynamics of fluids and material fatigue.

Live loads, sometimes also referred to as probabilistic loads, include all the forces that are variable within the object's normal operation cycle not including construction or environmental loads.

Roof and floor live loads are produced during maintenance by workers, equipment and materials, and during the life of the structure by movable objects, such as planters and people.

Bridge live loads are produced by vehicles traveling over the deck of the bridge.

Environmental loads

Environmental loads are structural loads caused by natural forces such as wind, rain, snow, earthquake or extreme temperatures.

Other loads

Engineers must also be aware of other actions that may affect a structure, such as:

• Foundation settlement or displacement
• Fire
• Corrosion
• Explosion
• Creep or shrinkage
• Impact from vehicles or machinery vibration
• Construction loads

Load combinations

A load combination results when more than one load type acts on the structure. Building codes usually specify a variety of load combinations together with load factors (weightings) for each load type in order to ensure the safety of the structure under different maximum expected loading scenarios. For example, in designing a staircase, a dead load factor may be 1.2 times the weight of the structure, and a live load factor may be 1.6 times the maximum expected live load. These two "factored loads" are combined (added) to determine the "required strength" of the staircase.

The size of the load factor is based on the probability of exceeding any specified design load. Dead loads have small load factors, such as 1.2, because weight is mostly known and accounted for, such as structural members, architectural elements and finishes, large pieces of mechanical, electrical and plumbing (MEP) equipment, and for buildings, it's common to include a Super Imposed Dead Load (SIDL) of around 5 pounds per square foot (psf) accounting for miscellaneous weight such as bolts and other fasteners, cabling, and various fixtures or small architectural elements. Live loads, on the other hand, can be furniture, moveable equipment, or the people themselves, and may increase beyond normal or expected amounts in some situations, so a larger factor of 1.6 attempts to quantify this extra variability. Snow will also use a maximum factor of 1.6, while lateral loads (earthquakes and wind) are defined such that a 1.0 load factor is practical. Multiple loads may be added together in different ways, such as 1.2*Dead + 1.0*Live + 1.0*Earthquake + 0.2*Snow, or 1.2*Dead + 1.6(Snow, Live(roof), OR Rain) + (1.0*Live OR 0.5*Wind).

Aircraft structural loads

For aircraft, loading is divided into two major categories: limit loads and ultimate loads.[11] Limit loads are the maximum loads a component or structure may carry safely. Ultimate loads are the limit loads times a factor of 1.5 or the point beyond which the component or structure will fail.[11] Gust loads are determined statistically and are provided by an agency such as the Federal Aviation Administration. Crash loads are loosely bounded by the ability of structures to survive the deceleration of a major ground impact.[12] Other loads that may be critical are pressure loads (for pressurized, high-altitude aircraft) and ground loads. Loads on the ground can be from adverse braking or maneuvering during taxiing. Aircraft are constantly subjected to cyclic loading. These cyclic loads can cause metal fatigue.[13]

See also

References

1. ^ASCE/SEI 7-05 Minimum Design Loads for Buildings and Other Structures. American Society of Civil Engineers. . p. 1. ISBN 0---2.

2. ^

   "1.5.3.1". Eurocode 0: Basis of structural design EN . Bruxelles: European Committee for Standardization. .

3. ^Avallone, E.A.; Baumeister, T. (eds.). Mark's Standard Handbook for Mechanical Engineers (10th ed.). McGraw-Hill. pp. 11&#;42. ISBN 0-07--1.

4. ^
   10 Questions You Should Know About What Is Adaptive Damping Suspension

   "2.2.1(1)". Eurocode 0: Basis of structural design EN . Bruxelles: European Committee for Standardization. .

   Recommended article:
   Type AF High Slip Resistance Girder Clamp
5. ^".2". International Building Code. USA: International Code Council. . p. 295. ISBN 1--26-6.

6. ^

   "2.2.5(b)". Eurocode 0: Basis of structural design EN . Bruxelles: European Committee for Standardization. .

7. ^Rao, Singiresu S. (). Reliability Based Design. USA: McGraw-Hill. pp. 214&#;227. ISBN 0-07--6.

8. ^

   International Building Code Section .1.

9. ^

   EN Euro code &#; Basis of structural design section 4.1.1

10. ^

    EN -1-1 Euro code 1: Actions on Structures &#; Part 1-1: General actions &#; densities, self-weight, imposed loads for buildings section 3.2

11. a b

    Bruce K. Donaldson, Analysis of Aircraft Structures: An Introduction (Cambridge; New York: Cambridge University Press, ), p. 126

12. ^

    Experimental Mechanics: Advances in Design, Testing and Analysis, Volume 1, ed. I. M. Allison (Rotterdam, Netherlands: A.A. Balkema Publishers, ), p. 379

13. ^

    Bruce K. Donaldson, Analysis of Aircraft Structures: An Introduction (Cambridge; New York: Cambridge University Press, ), p. 129

• Luebkeman, Chris H., and Donald Petting "Lecture 17: Primary Loads". University of Oregon. [1]
• Fisette, Paul, and the American Wood Council. "Understanding Loads and Using Span Tables". .[2] Archived -05-06 at the Wayback Machine

In construction and engineering projects, reliable and robust fastening solutions are crucial for ensuring structural integrity and safety. Among the various options available, anchor bolts stand out as versatile, high-strength fasteners that provide exceptional stability and support. 

The performance and understanding of anchor bolts and bolted joints are often underestimated. In reality, anchor bolts act as springs, utilising elasticity to provide stability and hold machine frames firmly to foundations.

In this comprehensive guide, we will explore the function, sizing, tension, materials, and installation of anchor bolts. By understanding these key aspects, you can ensure proper selection, installation, and long-term performance of anchor bolts, maximising their effectiveness in securing structures.

Understanding Anchor Bolts &#; Their Function

Anchor bolts play a critical role in the construction industry by securely fastening machine frames to foundations. Their primary objective is to establish a strong and stable connection, ensuring the machine remains firmly in place. By placing anchor bolts under sufficient tension, they can withstand the combined horizontal forces that act upon the machine. These bolts are responsible for maintaining the necessary clamping force that holds the machine against these forces.

Anchor bolts play a vital role in effectively transferring loads from the machine frame to the foundation. This transfer of loads ensures the structural integrity and longevity of the machine throughout its operational lifespan. By bearing the weight and distributing the forces evenly, anchor bolts prevent excessive movement or displacement of the machine, minimising the risk of damage or instability.

With their crucial function in providing stability and load transfer, anchor bolts are a fundamental component in the construction of structures. Properly installed and tensioned anchor bolts are essential for ensuring the safety, performance, and longevity of machines and structures in various industries.

Anchor Bolt Sizing 

Proper sizing of anchor bolts is crucial to ensure the structural integrity and stability of the machine or structure being fastened. Several factors come into play when determining the number, diameter, and length of anchor bolts.

One significant consideration is the shaking forces that the anchor bolts will need to resist. These forces can vary based on the specific application and environmental conditions. Additionally, the strength of the materials involved, such as the anchor bolts themselves and the foundation, must be taken into account. Anchor bolts should be selected to withstand the anticipated loads and forces they will experience during operation.

Concrete cracking is another factor to consider when sizing anchor bolts. Excessive or improper loading of anchor bolts can cause concrete to crack, compromising the stability of the structure. By properly sizing the anchor bolts, the risk of concrete cracking can be minimised, ensuring long-term stability and durability.

Mounting chock and grout factors should also be considered during anchor bolt sizing. These factors can affect the distribution of loads and the overall performance of the anchor bolts. Proper sizing ensures that the anchor bolts can adequately transmit the loads from the machine or structure into the foundation, preventing premature failure or displacement.

Undersized anchor bolt installations should be avoided at all costs. Insufficiently sized anchor bolts can lead to structural instability, compromising the safety and performance of the machine or structure. It is crucial to carefully analyse all the factors involved in anchor bolt sizing to ensure a proper and robust connection that can withstand the intended loads and forces.

By taking into consideration shaking forces, material strength, concrete cracking, and mounting chock and grout factors, engineers and construction professionals can determine the appropriate number, diameter, and length of anchor bolts, guaranteeing a secure and reliable fastening solution that meets the specific requirements of the application.

Anchor Bolt Tension

Anchor bolts derive their holding force through elastic stretching, comparable to springs. It is important to understand that the torque applied to the nut is not the primary factor in achieving the desired tension. Rather, the torque serves as a mechanism to stretch the bolt, resulting in the desired elongation and subsequent tensioning of the anchor bolt.

The stretch of the bolt itself is what determines its effectiveness in maintaining a secure connection. When the bolt is stretched, it develops a tension force that counteracts the external forces acting on the structure. This tension force is crucial for anchoring the machine or structure firmly in place and ensuring its stability.

It is worth noting that the torque applied to the nut should be carefully controlled during the installation process. However, it is not the sole indicator of proper tensioning. Instead, it serves as a means to achieve the desired level of stretch in the bolt. Monitoring the elongation of the bolt is essential to ensure that the anchor bolt reaches the required tension and can effectively resist the forces it will encounter.

Understanding that anchor bolt tension is primarily determined by the elongation of the bolt allows for precise and effective tensioning, ultimately ensuring the anchor bolts can provide the necessary holding force to secure the machine or structure against external loads and maintain its stability over time.

Anchor Bolt Materials

When it comes to anchor bolt materials, certain considerations are vital for ensuring a strong and reliable connection. For new installations and repairs, it is recommended to use high-strength bolts that meet ASTM spec A-193 standards. These bolts should have a tensile yield of 105,000 psi, ensuring they can withstand significant loads and forces.

Similarly, nuts used in anchor bolt assemblies should meet ASTM spec A-194 standards. Choosing nuts that meet these specifications ensures their compatibility and performance with the selected bolts. Moreover, the use of Super Nuts can offer additional advantages such as enhanced durability and resistance to loosening.

To address any lack of perpendicularity between the bolt and frame, the inclusion of hardened steel spherical washers is recommended. These washers help compensate for any misalignment and provide a more secure and stable connection between the bolt and the frame.

In terms of thread construction, rolled bolt threads are generally preferred over cut threads. Rolled threads provide a smoother and stronger thread profile, resulting in improved load-bearing capacity and reduced susceptibility to thread stripping or failure.

By selecting appropriate materials and components for anchor bolts the structural integrity of the machine or structure can be maintained, providing confidence in its performance and resistance to external forces.

Anchor Bolt Installation

Proper installation of anchor bolts is crucial for their effectiveness and the overall stability of the machine or structure. There are several key considerations to keep in mind during the installation process.

Using longer bolts during installation offers various benefits. Firstly, it allows for maximum stretch of the bolt, which is essential for achieving the desired tension. Additionally, longer bolts help move terminations and tensile stresses away from the surface of the block. This has the advantage of enlarging the cone of compression, effectively putting a larger portion of the block into compression. Moreover, this technique helps mitigate the potential effects of chock and grout creep as well as thermal expansion.

To ensure the integrity of the anchor bolt installation, it is recommended to wrap or sleeve the bolts along their entire length. This practice helps prevent shear cracks from occurring between the bolt and the concrete, ensuring a secure and durable connection. It also provides the longest possible free stretch length for the anchor bolt, allowing it to effectively bear the intended loads and forces.

In addition, designing an open relief area around the top of the bolt is beneficial. This design feature enables small bending adjustments to accommodate the frame. By allowing for these adjustments, the anchor bolt can better conform to the specific requirements and geometry of the frame, enhancing the overall stability and performance of the connection.

Stress in Threaded Nuts

In threaded nuts, the highest concentration of stress occurs within the first three threads. This means that the threads closest to the nut&#;s face bear the majority of the load. It is crucial to recognize this stress distribution when designing and assembling anchor bolt connections. 

While some may believe that using double nuts on anchor bolts can increase the joint&#;s strength, this is not the case. Doubling the nuts does not significantly enhance the strength of the connection. Therefore, it is advisable to avoid using double nuts and instead focus on proper tensioning and installation techniques to ensure the integrity and stability of the joint.

Preferred Anchor Bolt Terminations

To achieve optimal performance and load transfer, careful consideration should be given to anchor bolt terminations. Several preferred terminations can effectively support and transmit loads from the machine or structure to the anchor bolts. Options such as welded plates, embedded plates, or anchor rods offer reliable and robust connections.

• Welded plates involve welding a plate directly to the machine frame, providing a solid and secure termination point. 

• Embedded plates are embedded within the concrete foundation, allowing for a direct load transfer between the anchor bolts and the foundation. 

• Anchor rods, on the other hand, offer a versatile option by extending through the structure and providing a reliable connection point. 

By selecting and implementing these preferred anchor bolt terminations, engineers can ensure the durability, stability, and performance of the anchor bolt connections.

Conclusion

Anchor bolts are essential components in maintaining the stability and safety of structures. By gaining knowledge about their function, sizing, tensioning, materials, and installation techniques, informed decisions can be made to optimise their effectiveness. 

When it comes to anchor bolt replacement and installation, Alphatec Engineering stands out as experts in the field. Their expertise and experience ensure that anchor bolts are carefully selected, installed, and maintained, providing long-lasting and reliable support. By prioritising the proper selection and installation of anchor bolts, the safety and structural integrity of machines and structures can be significantly enhanced. Trust Alphatec Engineering for all your anchor bolt needs.