94 



STEEL OFFICE BUILDINGS. 



CHAP. II. 



as given in (i) and (2) are the most satisfactory columns for usual conditions. The Bethlehem 

 H columns in (n) and (12) make very satisfactory columns. While the Bethlehem H columns 

 require the driving of less rivets than are required to fabricate built-H columns, the extra cost 

 required to drill from the solid in heavy Bethlehem H columns makes the final cost of the two 

 types of columns practically the same for average conditions. Columns made of two channels 

 laced are deficient in lateral rigidity and should only be used for light loads. Z-bars are difficult 

 to obtain from the rolling mill and Z-bar columns should not be used unless it is knpwn that 

 Z-bars can be obtained. Additional sections are given in Fig. 14. 



Column Schedule. A column schedule should be prepared as in Fig. 6. The column schedule 

 should give the length, area of cross-section and the composition of every column in the building. 

 For the use of the shop draftsmen the dead load, wind load and eccentric stresses should be given 

 for each column. 



Column Details. Standard details for channel columns and for plate and angle columns are 

 given in Fig. 7. Details of channel columns are given in Fig. 8. Details of plate and angle 

 columns are given in Fig. 9 and Fig. 10. Details of column splices are given in Fig. 1 1 and Fig. 12. 

 Details of a column used in the Singer Building are shown in Fig. 27. 



Column Bases. Details of cast iron column bases as designed by the American Bridge 

 Company are given in Fig. 13 and Fig. 14. Intermediate sizes may be obtained by interpolation. 



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Sectional Side Elava+ion. 



FIG. 15. CAST STEEL BASE. 



FIG. 1 6. BUILT STEEL COLUMN BASE. 



Details of a cast steel column base used in the Singer Building are shown in Fig. 15. Details 

 of a built steel column base designed by Mr. E. W. Stern, Consulting Engineer, are shown in Fig. 16 

 Mr. Stern considers the built steel column base as cheaper and more reliable than a cast steel 

 base; and cheaper and very much more reliable than a cast iron base. In addition the base is 

 easily set and readily grouted. After setting, the base is grouted with I to 2 Portland cement 

 mortar. Bases of this design have been used for loads up to 1,600 tons. 



Anchors. Details of anchors are given in Fig. 17. Anchors for columns in tall buildings 

 should be calculated for the actual conditions. 



FOUNDATIONS. The foundation for a tall building will depend upon the height of the 

 structure, the total load on the foundation, the character of the soil, and the requirements of the 

 design and may be briefly described as follows. 



(1) Ordinary wall or pier foundations built on the natural soil. 



(2) Walls and columns supported by timber grillage resting on the soil. 



(3) Walls and columns supported on grillages made of steel beams or bars encased in concrete 

 and resting on the soil. 



(4) Piles of timber or concrete driven to rock or to a sufficient depth to carry the loads without 

 settlement. 



(5) Caissons as constructed in Chicago by excavating in an open well or shaft, curbing it 

 with timber, and then filling the well with concrete. 



(6) Caissons as constructed in New York by sinking steel cylinders, or steel and timber 

 caissons, or reinforced concrete caissons, usually by the pneumatic process and filling the shaft 

 with concrete. The first type of foundation, where the soil is compressible, can only be used for 



