Rivington's Notes on Building Construction, Volume 2

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Page 19 - ... convenience or economy. 3. The tie beam should be supported at such small intervals that it need not be too large for economy or convenience. It has been found by experience that these objects can be attained by limiting the distance between the points of support on the principal rafter to 8 feet. In determining the form of truss for any given span, it is therefore necessary first to decide the pitch, then roughly to draw the principal rafters in position, ascertain their length, divide them...
Page 320 - The plan is a symmetrical one, the main block being designed to accommodate two principal apartments, one on the ground floor and the other on the first floor...
Page 20 - ... the wall plate over the centre of the wall, so as to bring the weight fairly upon the masonry, but this increases the bearing of the tie beam and causes expense. Wall plates are therefore generally placed so as to be flush with the inner faces of the walls. At the angles of buildings the wall plates are halved, dovetailed, or notched into one another, and well spiked together, and halved or scarfed wherever it is necessary to join them in the direction of their length ; they should, however,...
Page 33 - The purlins if placed 2 feet apart and with 10 feet bearing may be made 3" x 6". The scantlings of the principal rafters, struts, and straining beam can be slightly modified by means of the following rough...
Page 4 - For a roof the plane of which inclines upwards at a greater angle than twenty degrees with the horizontal, the superimposed load, which shall for this purpose be deemed to include wind pressure and weight of snow and ice, shall be estimated at twenty-eight pounds per square foot of sloping surface, normal to such sloping surface, on either side of such roof. 13. For all other roofs the superimposed load shall be estimated at fifty-six pounds per square foot measured on a horizontal plane.
Page 21 - Fig. 324 shows the position of the wedges before tightening up. The slots should be so arranged that there is, before driving the wedges, a space in the king post at x above the upper gib, and one in the strap at y below the lower gib, so as to admit of the strap being raised until the tie beam is as close up to the king post as possible. Fi". 323. Fig. 324. The King Post, or
Page 8 - Fig. 321, lettered CE, P, B, G, H, are not portions of the truss itself, but are supported by it. It would for many reasons be inconvenient to have trusses such as that just described so close together that they would carry the boarding slates or other roof covering without any intermediate bearers.
Page 33 - For the tie beam, purlins and common rafters, so long as the depth is about double the breadth, J" deducted from the breadth requires J" to be added to the depth. J The joint of the tie beam with the principal rafter should be placed immediately over the supporting wall. If this cannot be conveniently done, the depth of the tie beam should be increased one or two inches.
Page 8 - Other members are also found necessary, such as wall plates (wp) to grip the ends of the tie beam and to distribute the weight over the walls ; a ridge piece (r) to unite the tops of the trusses longitudinally and receive the upper ends of the common rafters ; and pole plates (pp) to receive the feet of the common rafters. Fig.
Page 19 - ... following considerations : 1. The parts of the truss between the points of support should not be so long as to have any tendency to bend under the thrust ; therefore the length of the parts under compression should not exceed twenty times their smallest dimension.

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