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The wood ledger module provides the ability to calculate moments and shears in the ledger, as well as actual and allowable bearing loads on the attaching bolts.

 

The module allows the ledger to be attached to concrete or another wood member, and it automatically calculates the proper allowable bolt values.

 

All calculations are according to 2005 NDS and either 2006 IBC or 2009 IBC. Allowable bolt capacity at an angle to the grain is calculated using Hankinson's formula.

 

 

General Tab

This tab collects information on the main ledger size and stress grade, and bolt information.

 

Ledger Data: Enter the actual dimensions (not nominal) and the wood species of the ledger. The specific gravity will be retrieved from the internal databases (you can also revise the specific gravity).

 

Wood Stress Grade: Use the [Browse] button to access the built-in NDS stress database and retrieve the Fb and Fv values. You can also edit these values separately.

 

Bolting Data: Enter the bolt diameter and spacing. The yield strength of the bolt is fixed at 45 ksi in this module.

 

ASD or LRFD: Select the design method to be used. Load factoring and allowable stress calculations will applied accordingly.

 

 

When "Attached to Concrete" is set to [No]

 

When the user specifies the ledger is not attached to concrete, this implies that the ledger is attached to a supporting wood member. The display will

change to allow the width and species of the supporting member to be entered.

 

 

The following sketch clarifies the width dimension required for a wood supporting member:

 

 

Loads Tab

This tab allows you to apply vertical and lateral (in the plane of the wall) loads to the ledger.

 

One set of uniform load values can be specified, and it will be considered to act consistently along all areas of the ledger. For calculations purposes, this module considers the ledger a continuous beam over multiple supports.

 

One set of repeating point loads can be specified, where the input collects the magnitude, the starting location, and the spacing between subsequent loads. The module will consider all locations of the point loads over enough ledger spans between bolts to determine the governing case. For example, say your ledger bolting is set to 36" and the point load is set to 15". There will be multiple point loads between bolts, and on the NEXT span, the point loads will be in different relative positions with respect to the bolts. The module analyzes all conditions of that bolt pattern over enough ledger spans to determine the governing point load offset.

 

One set of horizontal (lateral) shear loads is allowed, in order to simulate wind or seismic load applied to the ledger and acting in the plane of the supporting wall.

 

 

Load Combinations Tab

This is the typical load combination tab with entries for load duration factors CD (ASD) and λ (LRFD).

Selecting the [Auto Reverse Wind Factors] and/or [Auto Reverse Seismic Factors] buttons creates additional load combinations that insert "-W" and "-E" whenever W and E are used.

 

Results Tabs

This set of tabs provides detailed results for the current calculation. The vertical tabs on the left edge of the screen allow you to select the two major areas available for review: Calculations and Sketch.

The Calculations tab offers the following results options:

Results tab presents a summary of the design for the current member by reporting the following:

 

Maximum Ledger Bending shows the load combination, applied moment and actual and allowable bending stresses. Note that no slenderness is considered for the ledger.

 

Maximum Ledger Shear shows the load combination, applied moment and actual and allowable shear stresses for vertical loads only. These stresses are taken at the point of bolt support of the ledger and no subtraction of uniform loads within a distance "ledger depth" from that support is considered.

 

Maximum Bolt Bearing Summary  Shows the vertical and horizontal components of force acting on the bolt for the governing condition. "Allow Diagonal Bolt Force" is the result of allowable parallel to grain and perpendicular to grain bolt capacities used for the "Angle of Resultant" in a Hankinson formula calculation.

 

Dowel Bearing Strengths give the allowable stress and resulting allowable bolt bearing stress considering NDS procedures and strengths and bolt size the user has entered.

 

 

Allowable Bolt Capacity tab provides the details of the bolt capacities according to the chosen NDS calculation method.

 

 

M & V Details tab summarizes the design values according to load combination for moment, shear and bolt forces.

 

 

The Sketch tab provides a graphic representation of the ledger currently being designed: