Anchor bolts, also called wedge anchors, are used to secure structures to concrete or masonry. The bolt extends into a hole drilled in the concrete, and it is held in place with a nut. It can be difficult for the layman to tell the difference between the myriad types of bolts available to consumers. For this reason, if you are considering a project in which you plan on utilizing anchor bolts, becoming aware of what specifications make anchor bolts functional can be helpful in choosing the proper building supplies.
Threading is an important specification for anchor bolts. The amount of threading on an anchor bolt can have an effect on how the anchor bolt is attached. Anchor bolts can be either fully threaded or partially threaded, with different lengths of the bolts threaded, but they must always be able to hold their load.
Ultimate Load Rating
Ultimate load rating is a specification that often comes with anchor bolts. The rating is a statement of the maximum amount of weight that an anchor bolt will be able to withstand before collapsing.
Working Load Rating
Working load rating is the load at which an anchor bolt will be able function to its fullest capability. And anchor bolt's working load rating is usually about 25 percent of its ultimate load rating. In other words, if an anchor bolt has an ultimate load rating of 9,000 lbs., its working load rating would be 2,250 lbs.
Tension and Shear Values
Tension and shear values also pertain to the level of weight that the bolt can take. However, tension and shear values are variable, depending upon the depth the which the bolt is immersed in the concrete or masonry. Sometimes, companies will provide only one tension and shear value. Usually, this value applies to a depth when the bolt is embedded beyond the minimum depth required for the bolt to be functional. Sometimes, manufacturers will provide several different values that apply to several different depths.
The type of concrete in which a particular anchor bolt's specifications are established can have a large effect on its tension and shear ratings. Types of concrete are differentiated in terms of density, which is measured in lbs. per square inch (psi). Most bolt specifications will be established using 2,000 psi, 4,000 psi or 6,000 psi concrete. Sometimes, a bolt will come with specifications at all these densities, but often they will not. Keep an eye out for this when comparing different bolt strengths.
Torque rating is the amount of torque that must be applied to an anchor bolt before it can be relied upon to provided the necessary level of weight support. If the torque is less or more than this specification, then load rating and tension and shear values will be different. For this reason, a wide variety of torque values are sometimes provided with anchor bolts by manufacturers.
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- Anchor Bolt Design Calculations
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