The Coliseum at St. Louis, Mo., is a rectangular brick building, 189 x 318 feet in size, intended for amusement purposes and as a place of popular assembly. The general construction of the building was described by Mr. E. W. Stern, M. Am. Soc. C. E., in a paper before the Engineers' Club of St. Louis, an abstract of which was published in the Engineering Record of Oct. 1, 1898. The building has an oval main hall, 186' 2" by 298*2" in size, roofed by arched spans and unobstructed by columns. Between the rounded ends of the steel framework of this auditorium and the outer brick walls are floors with iron columns and girders. The auditorium has a large central ground floor surrounded by ascending tiers of seats around the circumference of the structure, and there is a second inclined tier of seats forming a gallery. The arrangement and principal dimensions of the main trusses, girders, etc., is shown by plan and elevation diagrams in Fig. 236 and 237, respectively. The four main trusses are three-hinged arches, with the lower chord panel points above the floor line in the curve of a true ellipse. The end radial trusses correspond essentially to the semi-trusses of the main arch except for their top connection, where their top chords are attached to a semicircular frame supported by the end main trusses and designed to receive thrust, but no vertical reaction.

The roof covering of asphalt composition is laid on 1 3/8-inch boards, resting on wood joists 2 1/2 x 16 inches, 3 feet apart and ceiled underneath. These, in turn, are carried by the steel purlins of the structure, which are spaced about 16 feet apart. The gallery floor beams are carried on stringers of 8-inch channels spaced 3 feet 8 inches center to center, carried by girders running between, and supported by the arches. The rear stringer is a plate girder; the front one is a latticed girder, the gallery beams running through the latter and cantilevered out 5 feet 4 inches.

The loads, in accordance with which the trusses were figured, are as follows:

CASE I.

Wooden deck and gravel of roof. ..

17.5 lbs.

per sq. ft. vertically.

Steel..................

12.5 lbs

per sq. ft. vertically.

Snow and wind................

25.0 lbs.

per sq. ft. vertically.

Total......................

55.0 lbs

per sq. ft. vertically.

Add for floors, viz.:

Main floors, banks and galleries. ...

105.0 lbs.

per sq. ft. vertically.

Attic floors.............

60.0 lbs.

per sq. ft. vertically.

CASE II.

Wooden deck and gravel of roof. ..

17.5 lbs.

per sq. ft. vertically.

Steel...........................

12.5 lbs.

per sq. ft. vertically.

Snow................

10.0 lbs

per sq. ft. vertically.

Total......................

40.0 lbs.

per sq. ft. vertically.

Wind pressure over entire elevation of wall and roof of.........

30.0 lbs.

per sq. ft. horizontally.

LOADS ON PURLINS.

Wooden deck and gravel of roof. ..

17.5 lbs.

per sq. ft. vertically.

Steel................

3.5 lbs.

per sq. ft. vertically.

Snow and wind.............

25.0 lbs.

per sq. ft. vertically.

Total......................

46.0 lbs.

per sq. ft. vertically.

Fig. 236.   St. Louis Coliseum.

Fig. 236. - St. Louis Coliseum.

99 The St Louis Coliseum 300240

Fig. 237.

For the main trusses, in addition to the stresses of Case II., there was added the stress due to the wind bracing between these trusses.

For the radial trusses, in addition to loading of Case II., there was assumed an additional load of 50,000 pounds supposed to act up or down at the upper point of truss; this load being what was assumed probable in case there was slight unequal settlement of the footings.

For the half ring connecting the tops of the radial trusses there was another case assumed, besides Cases I. and II., viz., a thrust of 50,000 pounds at any point of the half ring; this being the thrust of a radial truss under its full live and wind load.

All the material used was of medium steel, excepting the rivets, which were made of soft steel. Both material and workmanship conform to manufacturer's standard specifications.

UNIT STRAINS.

Tension..........................

10,000 lbs.

per sq. in.

Compression, for lengths of 90 radii or under. .

12,000 lbs.

per sq. in.

Compression for length of over 90 radii.....

17,100-57

1śr

Combined stress due to tension or compression and transverse loading.............

10,000 lbs.

per sq. in.

Shear on web plates............

7,500 lbs.

per sq. in.

Shear on pins....................

11,000 lbs.

per sq. in.

Shear on rivets...............

10,000 lbs.

per sq. in.

Bearing on pins...................

22,000 lbs.

per sq. in.

Bearing on rivets.................

20,000 lbs.

per sq. in.

Bending, extreme fiber of pins...............

25,000 lbs.

per sq. in.

Bending, extreme fiber of beams..........

16,000 lbs.

per sq. in.

Lateral connections have 25 per cent. greater unit strains than the above.

In Case II. of trusses, the above unit strains were increased one-third.

The purlins are triangular trusses 4 1/2 feet deep, made of angles. The bracing between main arch trusses terminates at the bottom with heavy portal struts of triangular box sections. The lateral rods are not carried to the ground on account of the obstruction they would make. The radial trusses are coupled together in pairs with lateral rods down to the ceiling line. The thrust due to wind is transmitted from them into the line of girders around the structure at this point, and into the adjoining systems. The compression ribs of the main and radial arches are stayed laterally by angle iron ties, connecting to the first panel-point in the bottom chord of the purlins. In the planes of the first diagonal braces of the trusses above the haunches, diagonal rods connect the bottom ribs of the trusses to the upper ribs of the next trusses. No struts were used between the bottom chords, as they would have been directly in the line of vision from the rear gallery seats to the farther end of the arena. The front and rear girders supporting the gallery and main floor beams are tied together with a triangular system of angle iron bracing.

To provide for expansion, the radial purlins and all the girders between the arches have slotted hole connections in every alternate bay. The diagonal rods between the two lines of ridge purlins were tightly adjusted on a hot day. To prevent secondary strains in the half ring to which the radial trusses are connected at their tops, there is 1/16 inch clearance in all the pin holes. There is also clearance between the pin plates, so that the trusses and the ring can slide a little sideways on their pins. The lines of the arch trusses were laid out full size and the principal points checked by independent measurements in the template shop, and the work was accurately assembled.

The total weight of iron in the entire structure was 1,905,000 pounds, as follows: Main arches, each, 64,000 pounds; radial arches, each, 21,000 pounds; main floor stringers, each, 810 pounds; purlins between main trusses, each, 1,450 pounds; balcony floor stringers, each, 280 pounds; cast shoes, each, 3,000 pounds. There were 4,188 days' labor spent on the work in the shop and 3,550 days' labor during erection, the average number of men in the erecting force being about 50. The stress diagrams and detail plans of the steel frame were made under the supervision of Mr. Stern, in the office of the Koken Iron Works, who were contractors for the ironwork, and were submitted for approval to the consulting engineer, Mr. Julius Baier, Assoc. M. Am. Soc. C. E. Mr. C. K. Ramsey was the architect of the Coliseum and Mr. L. H. Sullivan was the consulting architect.