In a separate article entitled “Accurate Flitch Beam Design Made Easier with Software” there was an allusion to the difficulty associated with designing the connection between the solid sawn members and the steel members of a flitch beam.  In this article there will be a more in depth discussion on the methodology for attaching the different materials of a flitch beam so that all the materials act as one solid member.

Flitch beams must be connected together to appropriately transfer loads to the wood and steel portions of the beam in proportion to the relative stiffness of each material.  Most structural engineering software packages don’t provide this calculation; two sample methods are provided below for determining this connection.

Stresses in Beams
In a separate article entitled “Structural Analysis of a Beam” there was a brief discussion of stresses and their function in structural analysis.  In this article there will be a more in dept discussion of normal, bending, and shear stress.

Normal Stress
A normal stress is a stress that occurs when a member is loaded by an axial force.  The value of the normal force for any prismatic section is simply the force divided by the cross sectional area.

A normal stress will occur when a member is placed in tension or compression.  Examples of members experiencing pure normal forces would include columns, collar ties, etc.

The process used for determining the adequacy of a wood, steel, or even a concrete beam is essentially the same. Once a beam has been selected the method is as follows:

• Determine the loads
• Calculate the stresses
• Check the allowable stresses against the actual stresses.

Determine the Loads
The first step in the structural analysis of a beam is determining the amount of load, or weight the beam is going to support.  There are two major categories of loads: