8 



DEAD LOADS 



on walls will usually weigh somewhat less than the value given by 

 Formula ( I ) . The computed weights of Fink roof trusses without ven- 

 tilators and with purlins spaced from 4 to 8 feet are given in Table I. 



These trusses were designed by two different bridge companies to 

 serve as standards and represent minimum weights. The trusses with a 

 spacing of 14 feet were designed with minimum thickness of metal 3-16" 

 and minimum size of angles 2" x i^" x 3-16". In the remainder 

 of the trusses the minimum thickness of plates was *4" and minimum 

 size of angles 2" x 2" x J4". The trusses are all too light to give good 

 service although their use in temporary structures may sometimes be 

 allowable. 



Weight of Purlins, Girts, Bracing, and Columns. Steel 

 purlins will weigh from 1^2 to 4 pounds per square foot of area covered, 

 depending upon the spacing and the capacity of the trusses and the 

 snow load. If possible the actual weight of the purlins should be cal- 

 culated. Girts and window framing will weigh from i% to 3 pounds 

 per square foot of net surface. Bracing is quite a variable quantity. 

 The bracing in the planes of the upper and lower chords will vary from 

 */2 to i pound per square foot of area. The side and end bracing, eave 

 struts and columns will weigh about the same per square foot of sur- 

 face as the trusses. 



Weight of Covering. The weight of corrugated iron or steel 

 covering varies from \y 2 to 3 pounds per square foot of area. 



WEIGHT OF FLAT AND CORRUGATED STEEL SHEETS WITH 2^2 INCH 



CORRUGATIONS. 



