CIVIL ENGINEERING FORMULAS

TABLE 3.1 Strength of Round-Ended Columns According to Euler’s Formula*

Low- Medium-

Wrought carbon carbon

Material† Cast iron iron steel steel

Ultimate compressive strength, lb/in^2 107,000 53,400 62,600 89,000

Allowable compressive stress, lb/in^2 7,100 15,400 17,000 20,000

(maximum)

Modulus of elasticity 14,200,000 28,400,000 30,600,000 31,300,000

Factor of safety 8 5 5 5

SmallestIallowable at worst section, in^4 Pl^2 Pl^2 Pl^2 Pl^2

17,500,000 56,000,000 60,300,000 61,700,000

Limit of ratio, l/r 50.0 60.6 59.4 55.6

Rectangle 14.4 17.5 17.2 16.0

Circle 12.5 15.2 14.9 13.9

Circular ring of small thickness 17.6 21.4 21.1 19.7

*Pallowable load, lb; llength of column, in; bsmallest dimension of a rectangular section, in; ddiameter of a circular sec-

tion, in; rleast radius of gyration of section.

†To convert to SI units, use: 1b/in (^2) 6.894kPa; in (^4) (25.4) (^4) mm (^4).
rdw^1  8 ,l/d
r^1  4 d,l/d
rbw^1  12 ,l/b
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