Patent GB-506344-A (GB)
Title: Improvements in arched building structures for bridges and roofs
IPC: E01D1/00
Filed: 1937-11-23
Abstract: 506,344. Bridges; roofs; girders. HEIDENSTAM, E. J. VON. Nov. 23, 1937, Nos. 32272, 32273, and 32274. Convention dates, Nov. 25, 1936, Feb. 26, 1937, and April 15, 1937. [Classes 20 (i) and 20 (iv)] A bridge or roof structure comprises an arch 1 having at least one concave depressed point 40, a tie 2, a system of braces arranged between the arch and the tie, and at least one strut 31 connected to the arch, on the one hand, and the tie and brace system, on the other hand, the various parts of the structure being so arranged that when the arch is subjected to an unevenly distributed primary road one or more of the braces causes a secondary loading of the arch which counteracts deformation of the latter due to the primary load. The strut 31, Fig. 1, is connected between the point 40 and the central point 32 of the tie 2, and two bow-shaped braces 35, 36 of angularlybent form are connected between the ends of the arch and the point 32, vertical suspension rods 9 being connected between the arch and the braces 35, 36. A primary load applied to the left-hand portion of the arch will tend to depress this portion of the arch and correspondingly bulge the right-hand portion; the brace 35 and rods 9 will thus become unstrained since they are pure tension members, and the increased tension in the left-hand part of the tie will be balanced by tensile stresses in the brace 36, the corresponding suspension rods 9, and the right-hand part of the tie. The construction shown in Fig. 1 may be modified by providing, in each half of the arch, two or more dissimilar bow-shaped braces connected between the point 32 and the end of the arch. The suspension rods 9 may extend down to, and be connected with, the tie 2, which may then serve as a bridge roadway or be constructed as a girder for carrying travelling cranes &c. The tie 2 shown in Fig. 1 may consist of two angularlyinclined parts meeting at the central point 32 where they are joined rigidly or articulately; the suspension rods 9, in this case, may also be extended downwardly to carry a bridge roadway which passes above, below, or through the central point 32. The arch shown in Fig. 6 is provided with the bow-shaped braces 35, 36, and bent braces 37, 38 connected between the point 40 and the ends of the arch; compression members may also be connected between the braces 37, 38 and the arch, and these members may extend down to the braces 35, 36. Those parts of the bow-shaped braces 35, 36 adjacent the point 32 may be made straight for a greater distance than shown in Fig. 6 and unconnected with the arch ; braces having forked outer ends are then connected between the point 32 and the braces 37, 38 and arch. The braces 37; 38 shown in Fig. 6, may be straight and each may be connected with the point 32 by a single tension member. The arch shown in Fig. 9, having bow-shaped braces 35, 36 and straight braces 37, 38, may be stiffened by tension members 54, 55 which are connected with the braces 35, 36 and braces 37, 38, and vertical braces 56, 57 extend to the arch and braces 35, 36 from the points of connection of the tension members 54, 55 with the braces 37, 38 ; the tie 2 may be bent (as shown) at 2<11> in Fig. 9. The arch shown in Fig. 10 is provided, in each half, with a straight brace 37, 38 and two bow-shaped braces a, b, c, d, and e, f, g ; the two bow-shaped braces are connected by a bent brace 61a, 61b which is also connected both with the arch and the point 60 of intersection between the two bow-shaped braces. The arch shown in Fig. 2 is provided with braces extending from the point 32 to the arch, some of these braces being straight as. at 42 and others having forked ends 41a, 41b. The portions of the arch between the ends thereof and the point 40 may be formed either as continuous curves or of polygonal shape. The arch may also be formed with more than one concave depressed portion, in which case a strut is arranged between each such portion and the tie. The braces need not extend from the ends of the arch, but may be secured near the ends so that a portion of the end of the arch may be regarded as a part of the brace system. All the braces need not be connected with a common point on the tie. Instead of the various braces being connected at the point 32, they may be connected with the strut 31 somewhat above this point. The connection at the points 32, 40, and between the ends of the arch and the tie, may be of hinged type. A bridge structure may be constructed so that its dead load causes only small moments in the arch; in this case, the arch, braces, tie, and suspension rods are first erected, and the tie and braces are then subjected to an initial tensile stress of the desired magnitude by means of hydraulic jacks or the like. The Specification as open to inspection under Sect. 91 describes also an arch 1, Fig. 3 (Cancelled) with a centrally-bent tie and braces 5, 6 connected between the central point of the tie and the arch. The outer end of each of the braces 5, 6 may be either forked or provided with a girder portion which is connected at its ends to the arch. More than two inclined braces 5, 6 may be provided, and an additional vertical brace may also be inserted. A bridge roadway may be supported from the arch by rods 9 which may be connected with the braces 5, 6. The arch shown in Fig. 7 (Cancelled) is provided with two ties 15, 16, each of which is bent at 17, 18, and inclined or vertical braces 19, 20 extend from the points 17, 18 to the arch. If the ties 15, 16 are connected at the point 21, braces may extend from this point to the arch. Each of the bow-shaped braces 22, 23 shown in Fig. 10 (Cancelled) extends from the central point 4 of the tie to one end of the arch, and is connected to the arch by rods 9 which may extend downwardly so as to support a bridge roadway 8 ; two such braces 22, 23 may be arranged in each half of the arch. The arch shown in Fig. 12 (Cancelled) comprises a straight tie 2, two bow-shaped braces 35, 36, a strut 31, inclined braces 37, 38, and vertical braces 9; the arch is connected with the braces 37, 38 by struts 39. This subject-matter does not appear in the Specification as accepted.