

SPECIFICATIONS FOR STEEL MINE STRUCTURES. 



and 15 in. I -brains @ 42 Ib. at the top, the girders being spaced 3 ft. sJ in. center to center. The 

 in. tin M<lr ninU-rs are composed of two I-beams 15 in. @ 42 Ib., and one channel 15 in. @ 33 Ib. 

 Tin- || in. pl.itr floor is carried on 12 in. I-bcams spaced about I ft. 6 in. centers. The steel plate 

 floor is placed at a slope of 8 in. in 12 in., and it is stated that 95 per cent of the coal can be with- 

 dr.iwn from the bin. The bins discharge through vertical gates in the sides into motor-driven 

 larrirs, which run to the coke ovens. The vertical gates arc raised by rack and pinion and chain 



\\hrt 1>. 



Data on ten steel coal tipples are given in Table VI. For additional examples and data on 

 steel coal tipples, see the author's "The Design of Mine Structures." 



SPECIFICATIONS FOR STEEL HEAD FRAMES AND COAL TIPPLES, WASHERS 



AND BREAKERS.* 



PART II. 

 BY 



MILO S. KETCHUM, 

 M. Am. Soc. C. E. 



1912 



GENERAL DESCRIPTION. 



198. Types of Structure. The structure shall be of a type that will give maximum rigidity 

 and strength. The structure shall be of a type in which the stresses can be calculated either by 

 statics or by taking into account the deformations of the members. 



199. Bracing. All bracing shall be stiff, and shall be riveted together at all intersections to 

 give maximum rigidity. 



200. Proposals. Contractors in submitting proposals shall furnish complete stress sheets, 

 general plans of the proposed structures, giving sizes of material, and such detail plans as will 

 clearly show the dimensions of the parts, modes of construction and sectional areas. 



201. Detail Plans. The successful contractor shall furnish all working drawings required 

 by the engineer free of cost. Working drawings will, as far as possible, be made on standard 

 size sheets 24 in. X 36 in. out to out, 22 in. X 34 in. inside the inner border lines. 



202. Approval of Plans. No work shall be commenced or materials ordered until the working 

 drawings are approved in writing by the engineer. The contractor shall be responsible for dimen- 

 sions and details on the working plans, and the approval of the detail plans by the engineer will 

 not relieve the contractor of this responsibility. 



LOADS. 



203. The structures shall be designed to carry the following loads without exceeding the 

 permissible unit stresses. 



204. Dead Loads. The dead loads shall consist of the weight of the head sheaves, sheaves, 

 blocks and girders, the weight of the structure, and all concentrated machinery and equipment 

 loads. 



205. Working Loads. The working loads on head frames for, vertical shafts shall be taken 

 as equal to 



K = 2W+ R + (W + R)f (i) 



where K = the working stress in Ib. at the head sheave at the instant of picking up the load; 

 W = the gross load of the cage or skip and the load of ore or coal in Ib. ; R = the weight of the 

 rope from the head sheaves to the bottom of the shaft in Ib. ; and / = coefficient of friction of the 

 rope, skip and sheaves, which may be taken at o.oi to 0.02 for vertical shafts and 0.02 to 0.04 for 

 inclined shafts with ropes supported on rollers. 



206. For inclined shafts the working load shall be taken as 



K' = (aW + R) sin 6+ f(W +R) cos 9 (2) 



where 9 = the angle of inclination of the shaft with the horizontal. 



* From Specifications for Steel Mine Structures as printed in the author's "The Design of 

 Mine Structures." Part I is "Specifications for Steel Frame Buildings" as printed in Chapter I. 



