Overview

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1863 Excerpt: ...by overturning. If in an arch the joints of rupture be at the springing lines and the extrados of the crown, the horizontal thrust is- -, in which a is the distance from the springing line to the perpendicular, through the centre of gravity; b is the vertical distance equal to the rise of arch + thickness of ringstones, w the weight of half the arch. The conditions of equilibrium of the abutment are simply that the moments of the horizontal and vertical forces shall be equal, the weight of the arch being applied at the springing line. Although it would appear from the preceding statements, copied literally from the manuscript referred to, that the results given by this formula can be relied upon in practice, yet, notwithstanding the evidence furnished by the Monocacy aqueduct, we cannot think that the dimensions given by the formula are sufficient. When the stone is extremely hard, and the pressure upon it very small in proportion to its capability of resistance, the result may be sufficiently great, but in other cases it cannot be trusted. In fact, it is evident that the formula has been deduced upon the supposition that the pressures are thrown entirely upon the points D and 0, but, unless the strength of the material be almost infinite, these points could not sustain the pressure; the portions of the stone lying at these points would break off, and the points of contact D and 0, being thus brought nearer together, would render the line of direction of the pressure more nearly horizontal, increase both the horizontal force at 0 and the leverage e s, or L X at which it acts, and consequently require a greater thickness of abutment to resist its effects. That which we believe to be the true method of determining the equation of equilibrium of an arch, ...

Full Product Details

9781231069394

Table of Contents

Reviews

Author Information

Tab Content 6

Countries Available