Tables to Summarize Your Calculations

The table below summarizes the truss calculations.  These calculations are for a single truss subjected to 1,000 lbs.  Please use the full 1,000 lb. load in your truss calculations.  Do not divide the 1,000 lb. load by the number of parallel trusses used for your design (that is, don't base your calculations on 500 lbs. if your design has two parallel trusses).

Members Member
Diameter
(in)		 Member
Length
(in)		 Number
of Dowels
in Member		 Total Member
Force
(lbs)		 T
or
C		 Axial
Stress
(psi)		 Load to Buckle Member
(lbs)
AB, DE              
AG, EF              
BC, CD              
BG, DF              
CG, CF              
GF              

The next table summarizes the calculations used to predict the failure load. This table should also be based on 1,000 lbs. being applied to a single truss.

Members T
or
C		 Total Member
Force
(lbs)		 Force to Cause Pullout
(lbs)*		 Pullout
FS		 Load to Buckle Member
(lbs)		 Buckling Load
FS		 Axial
Stress
(psi)		 Dowel
Strength
(psi)		 Axial
Stress
FS
AB, DE                  
AG, EF                  
BC, CD                  
BG, DF                  
CG, CF                  
GF                  

* This is based on information from the joint strength laboratory. If there are two dowels that make up a member, the number taken from the joint strength laboratory should be doubled.

Pullout FS = Force to Cause Pullout / Total Member Force due to 1000 lb Load

Buckling Load FS = Load to Buckle Member / Total Force in Member due to a 1000 lb. Load

Axial Stress FS = Dowel Strength / Axial Stress in Member for a 1000 lb Load

From the table above, the member with the lowest factor of safety is the critical member.  The predicted failure load can be obtained as follows:

Predicted Failure Load = 1000 lbs * FS * Number of Parallel Trusses