The New Tay Bridge; A Course of Lectures Delivered at the Royal School of Military Engineering at Chatham, November 1888 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1889 edition. Excerpt: ...The arrangement for carrying the girders at the top of these superstructures differs considerably at the central spans (Type II.) from that at the spans south and north (Types I. and III.) At the central spans, where the girders are above the rails, there arc only two girders, and each is supported directly by one shaft of the superstructure; their weight and that of the rolling load is thus transmitted directly down to the cylinders and foundations. To enable this to be effected, at the top of each shaft are four box girders, two placed in the direction of the girders and nearly under them, and two at right angles; these carry a steel plate which supports the bearings of the girders; the connecting arch at these piers simply acts as a tie to the shafts at their tops (see Plate VI.). At the south and north spans (Types I. and III.), where there are four girders, and where the two intermediate ones, which carry the chief part of the weight, are situated over the connecting arch, the arch acts, to a certain extent, as a girder as well as a tie to the shafts. To effect this, there are at the top of these superstructures four box girders, one under each main girder, and under these, are frameworks of angle irons riveted to the bottom of the box girders, and to the plates of the superstructures (see Plate V.). By this means, and by horizontal and vertical cross bracings, and gussets, in the soffit of the arch, the weight of the girders and rolling load, is transmitted to the shafts, and so to the cylinders and foundations. In the case of the piers (Nos. G5-77) where their height is not sufficient to permit of shafts with connecting arches, the superstructure is constructed in the same manner as the upper part of those already described, above...