This section is from the book "A Practical Treatise On The Joints Made And Used By Builders", by Wyvill J. Christy. Also available from Amazon: Practical treatise on the joints made and used by builders.
Splayed Joint is a scarf in which the lapping ends are bevelled or cut slantingly, as in Fig. 58, so as to be oblique to the upper and under surfaces of the lengthened beam. Splice Joint is another term for a scarf joint. Timber piles are sometimes lengthened by splices, often made with long bevels or splays strengthened with wrought iron bands and straps. Fish joints might perhaps be also allowed to enjoy the synonym of splice joints, since fish plates are known in some parts by the name of splices.
Square Joint is one in which the plane of the joint is parallel and perpendicular to the fibres of the two pieces respectively, as occurs when a post stands on a curb or sill. The feet of struts wherever possible should be cut square to the direction of their own fibres.
This is an abutting joint strengthened by a stirrup iron, which is a strap turned up from iron usually about 2½ in. by 3/8 in., and of the form shown in Fig. 59. The stirrup is secured with bolts and nuts, and keys or wedges, otherwise called cotters. The same shaped strap is passed sometimes round the feet of principal rafters, and bolted through the tie-beam to take the stress off the mortise in their effort to spread.
This differs from a strap and bolt, or strap and cotter joint, inasmuch as the strap is continuous, and girts the work somewhat like a hoop does a cask, being either riveted or welded into a band, as in Fig. 45, or else having screwed ends which pass through a bearing or check plate, as with the kicking strap in Fig. 60, so as to be screwed down upon it with nuts. The strap is usually turned up from iron about 2½ in. by f in., and when of the welded description, requires to be put on hot, and the end of the timber over which it is slipped before being forced home to be slightly eased or tapered; besides which, dry weather should be selected for the operation. Either kind above mentioned may often be kept in place by coach screws. Lap joints, and those between the flitches or pieces of built beams, depend entirely upon the holding powers of the straps, when thus used, for their reliability, and consequently those of doubtful forging should be rejected without any scruples. When timber shrinks, in the course of time straps are liable to slip, and therefore in this respect, and especially when used with green timber, they are inferior to bolts.
Strap and Bolt Joint occurs when an abutting joint is secured with an iron strap and bolt, the strap consisting of a flat bent piece of wrought iron, from 1½ in. to 2½ in. wide, and about ¼ in. to ½ in. thick. "When used for connecting the foot of a rafter with a tie-beam, as in Fig. 61, it is indiscriminately called a heel strap or stirrup, and its two ends are usually swelled out into eyes to hold the screw bolt, which passes through the tie-beam near its neutral portion, and not so low down as the engraving represents. When the strap is attached to a suspending piece to support a tie-beam, it is termed a stirrup, the part which it embraces being all bolted through together, and secured with nuts and washers complete. This mode of fastening does not admit of adjustment. Variously shaped straps are employed in conjunction with screw bolts in framing together the component parts of trusses, partitions, domes, spirelets, bridges, and all sorts of heavy timber structures, but they are either turned-up pieces similar to the above, having equal and opposite ends, and corresponding holes formed therein for the bolts to fill, or else they may consist of loose duplicate pieces of identical form, having two or more tails or branches placed on opposite sides of the framing, so as to admit of being bolted together over the joint with the thickness of the framing between them.
In many cases, however, the duplicate strap is dispensed with, and washers used in lieu thereof. Settlement subjects this description of fastening, which has been previously noticed under Banded Joint, to cross strain. Fig. 62 shows one method of securing a strut to a rafter by such means. Straps and bolts, before using, should be preserved from oxidation, as remarked under Bolted Joint.