Fig. 3250.
Fig. 3251. Fig. 3252.
“A double riveted butt joint with double straps is shown in [Fig. 3250], and a treble with double straps in [Figs. 3251] and [3252].
“Third. By various arrangements of the rivets in conjunction with butt joints and double straps, with which it is not necessary, at this point, to deal.
“One of the great advantages obtained by the use of the double strap is that of bringing the rivet into double shear (or in other words, the rivet must shear on each side of the plate, or in two places, instead of between the plates only, before the joint can give way by shearing), and thus obtaining an increased calculated strength of 13⁄4 times the ordinary or single shear, the rule being to find the rivet strength in the ordinary way (as before explained), and then multiply the result by 1.75.
“The Board of Trade rules for spacing the rivets of these joints are as follows: