Modern Gasworks Practice

644 MODERN GASWORKS PRACTICE stiffeners, and in. this way assists in counteracting the compression in the curbs. If Bückling or distortion of the curb took place the ring tension would have a ten.den.cy to right the whole to its circular form, but the effect would be almost inappreciable. By a consideration of the main forces, it may be shown from the polygon of Fig. 394.'—Top Cubbs for Gasholdebs. forces (Fig. 393) that the resultant acts in such a direction as to induce a compressive stress in the curb. The direction of the resultant will, in faet, be horizontal and in alignment with the direction of the wind. In the diagram of forces (Fig. 393) the Fig. 395.—Common Designs for Bottom Curbs. resultant has beeil slightly tilted in order to show the conditions more clearly. Failure of the curb will be due, as may be seen, to an excessive compressive ring stress. In