GOVERNMENT BUILDING, ST. Louis EXPOSITION.* 



The Government Building at the St. Louis Exposition had a steel 

 framework with steel arch trusses of the three-hinged type. The span 

 of the arches is 172 ft. c. to c. of pins, and their rise from heel pins to 

 center pins is 66 ft. 9^ in. The trusses are spaced 35 ft. apart, and 

 are connected laterally by six lines of lattice girders, carrying the 

 posts of the main roof and monitor roof, and by eight other intermedi- 

 ate transverse struts. A horizontal wind strut truss is located as shown 

 in Fig. 184. 



The assumed loading was as follows : Dead Load : Roof, 10 Ibs. 

 per sq. ft. on slope; dome, 12 Ibs. per sq. ft. of roof surface; side 

 walls of dome and building, 15 Ibs. per sq. ft. of surface; trusses, 10 

 Ibs. per sq. ft. of floor surface. 



Wind Load: Side walls, 20 Ibs. per sq. ft.; dome, curved, 15 Ibs. 

 per sq. ft. of projection on a vertical surface. 



Snow Load : On roof of main building, 20 Ibs. per sq. ft. hori- 

 zontal ; reduced to 10 Ibs. per sq. ft. on ventilator over center. 



The revised estimate of loads for a 35-ft. bay figured out as fol- 

 lows, per sq. ft. of horizontal projection : 



Lbs. per sq. ft. 



Weight of steel i3-i 



" roof 6.6 



" tin covering 0.5 



Actual roof 20.2 



Calculated total 21.5 



The loading on one truss for the 35-ft. bay was : 



Actual Weight in Ibs. Estimated Weight in Ibs 



Total Dead Load 40,500 70,000 



Total Steel 80,000 64,000 



Grand Total 120,500 I34,ooo 



The arches are built up of channels, plates and angles, and have 

 4^-in. shoe pins and 3-in. center pins. The shoe pins of each truss 

 are connected by a tie bar consisting of a line of Q-in. I-beams. The 

 stresses in the arches are given in Fig. 183, while the details are shown 

 in Fig. 184. 



* Engineering News. 



