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Fastener information is entered for deflection calculations only, it has no impact on hold-down capacity.
Vertical Bolt
This group pertains to bolted, threaded rod or anchor bolt attaching the brackets to each other or one bracket to the foundation or some other anchoring mechanism.
Used to calculate the additional elongation for that portion of an anchor bolt in excess of the maximum bolt length for published displacement.
Elongation is calculated by the formula PL/AE, where P is the strength-level uplift force, L is the bolt length as input in the Structure dialog for each building level minus the maximum bolt length for given displacement that is input here, A is the cross-sectional bolt area, and E is the steel modulus = 2.9 x 10^7 psi
No/with anchor bolt
These buttons allow you to indicate that the connection does not have an anchor bolt, disabling the other vertical bolt inputs and causing the program to dispense with anchor bolt calculations.
No anchor bolt
Steel strap or plate is attached to upper and lower studs using nails or bolts. Does not include a vertical anchor bolt, so published elongation value is the only source of elongation.
With anchor bolt
Hold-down assembly contains either one or two steel brackets attached to each other or to the foundation with a threaded and bolted steel rod or anchor bolt. The bracket(s) are attached to the upper and lower wall studs with vertical bolts. Displacement values and manufacturer's anchor bolt length entered are for one bracket; these values are doubled in Shearwalls when two brackets are specified in the Wall or Opening input views. The capacity is the same regardless of whether one or two brackets is used.
Center Line
The distance from the outer face of the bracket, normally attached to the inner face of the end stud pack, to the center line of the anchor bolt. Used to determine the location of the hold-down or compression force in determination of the moment arm for overturning and deflection calculations
Diameter
Shank diameter of anchor bolt, used in elongation calculation. You can select from list or enter custom size. Used to calculate cross sectional area A in the formula PL/AE for anchor bolt elongation.
Max Length for Given Elongation
The length of anchor rod the manufacturer used in tests to determine the displacement. It is usually found in a note in the product literature or evaluation reports. It is subtracted from the hold-down bolt length input in the Structure dialog to get L in the formula PL/AE for additional anchor bolt elongation.