Book Description:
Purchase of this book includes free trial access to www.million books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: 2. By its own weight, which varies as its own height and diameter. 3. By the depth it is sunk into the ground. 4. By the resistance from friction of the ground on its surface. 5. By the safe load on the base. 6. By its flotation power, or loss of its weight from immersion in water. It is evident for the cylinder to be stable that the safe load on the base, plus the resistance from friction of the ground on its exterior surface, plus the flotation power, must equal the weight superimposed. plus the weight of the cylinder complete; and may thus be expressed : Let S = Safe load on the base of a cylinder. K = Eesistance from friction of ground on the surface of a. cylinder. F = Flotation power or loss of weight of the cylinder from immersion in water. W = Weight superimposed, including the rolling load. C = Weight of cylinder complete. Then for cylinder to be stable (S R F) must not be less than (W C). CHAPTER III. Load On The Base. Having calculated in detail the required diameter of a cylinder pier for a railway bridge, the load upon the base will be especially examined; but here it is advisable to name a few points to be considered in deciding upon the width of the openings and the form of the superstructure. In designing most bridges, the chief object is to determine the number of spans required in a certain length to give the necessary stability and utility at a minimum cost; but the nature of the ground may govern the number of openings, as the safe load upon it may not allow of the most economical spans being adopted, because they would cause too great a weight upon the foundations, its even distribution being considered expedient. Also, if the current of a river is swift, the bed covered with boulders to an unknown depth...
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