THE MiTek® SYSTEM
(incorporating Gang-Nail®, Hydro-Nail® and eCo®) (continued)
 
 
SPECIAL DESIGN
 
The examples of special design shown on this page give only a limited view of the many which have been achieved using the MiTek systems. This encourages the designer to use the MiTek systems whenever an economical and architecturally sound design is required.
 
 
 
 

 

ESTIMATING THE RAFTER DEPTH

Triangular Trusses - Pitch 15 degrees

Estimating the Rafter Depth. The rafter depth is primarily controlled by the span and loading on the truss and its overhang. The simple table below allows the depth of the rafter to be estimated for trusses over 15º in pitch. Both table 7.3.1. and Table 7.3.2. must be checked and the larger rafter size used in the estimate.

Table 7.3.1 ESTIMATING RAFTER DEPTHS FROM TRUSS SPAN AND LOADING

Table 7.3.2
Note: These highly simplified tables are based on common grades of timber, fixed truss and purlin centres, and do not take the truss configuration and pitch into account. They are provided only to enable the architect to complete his drawings. MiTek truss designers may well achieve a more economical solution at design stage.
 
INDUSTRIAL TRUSSES - ECONOMIC PROFILES
 
Large spans can be achieved in timber, provided a minimum ratio of span/depth is achieved. With sufficient height, spans of up to 28 metres have been built, often at considerable savings over other forms of construction. Several large shopping centres have been successfully designed and erected using large span timber trusses.
 
 
SPANS 0 - 25 METRES
For trusses with ratio: Span/Average Height <12
 
 
SPANS 0 - 25 METRES
For trusses with ratio: Span/Height <12
  
  

Large span industrial trusses, their purlins and bracing, may also be constructed using vertically laminated timber members of either S.A. pine or saligna. This high strength material allows much shallower trusses, spaced at wide centres, to be designed and constructed. Span to height ratios as high as 15 can be achieved at truss centres of up to 3 metres and wider, to provide a very competitive solution for industrial and commercial buildings. Where necessary, corrosion resistant connectors can be specified to give a maintenance-free solution.