An investigation of hooped concrete columns . hould te^re account of these facts. Effect Of Amount of The relation between theultimate strength of the column and the amount of spiral isshown for the 5-ft. columns of 1-2-4 concrete by the lower curveon page 752. From this curve we see that r of spiral adds anaverage of 927 lb. per sq. in. to the strength of the value is somewhat lower than that usually found. From Table 71, page 219, we find the ultimate strengths |of the columns of 1-1-2, 1-2-4, and 1-3-6 mixtures to be 5080,4400, and ^810 lb. per so. in., for spiral.
An investigation of hooped concrete columns . hould te^re account of these facts. Effect Of Amount of The relation between theultimate strength of the column and the amount of spiral isshown for the 5-ft. columns of 1-2-4 concrete by the lower curveon page 752. From this curve we see that r of spiral adds anaverage of 927 lb. per sq. in. to the strength of the value is somewhat lower than that usually found. From Table 71, page 219, we find the ultimate strengths |of the columns of 1-1-2, 1-2-4, and 1-3-6 mixtures to be 5080,4400, and ^810 lb. per so. in., for spiral. Taking thestrengths of the concretes as being 3400, 1900, and 800 lb. persq. in., we have the added strengths 1680, 2500, and 3016 sq. in. For 1 these are G24, 927, and 1120 lb. per s-. may seem strange that the rich concretes show less increaseper percent than do the poorer ones, but when it is rememberedthat the value of ^oissons ratio is higher at all loads forrich than for lean concretes, this seems reasonable. The discuss-. ion on page 31 also has on this point. From a study of the curves on page 3CB, the following re-lation was found to be true for the 5-ft. columns havinc- reinforcement: Taking those parts of the load—deformationcurves between the origin and the points at which the stress inthe spirals is e^ual to 50 OOClD. per sq. in. ,we find that theareas under the curves for the 1-1-2 and the 1-2-4 concretes areequal, while the area under the curve for the l-?-6 concreteis about 50$ higher. mhe following conclusions are based uponthe study of the data of the columns and may not apply tocolumns of other sizes and made from other aggregates. 1. - The value of the initial modulus of elasticity of thecolumn does not depend upon the amount of spiral reinforcement,but for any amount it is somewhat less than that for plain concre 2. The ultimate strength of the 5-ft. columns depends uponthe amount of spiral and upon the mi
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