Reinforced Concrete Design (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: ...minimum positive or maximum negative moment at midspan by M = (HWd-5W() where W( = total load supported by beam, Wd = dead load supported by beam. It will be seen that for a given load to be supported, this distribution gives a higher moment than a uniform load on the same span. (3) Concentrated loads at midspan.--Concentrated loads may occur on beams, either by the action of wheel loads or the like, or by the reaction on to a main beam from a secondary beam, as in Fig. 93. Taking, as before, an interior bay of a beam with an infinite number of spans, we have from Appendix 1.14, the maximum positive moment at midspan, M = (3W(-Wd) and minimum positive or maximum negative moment at midspan, M = (3Wd _ Wt) where W( and Wd are the concentrated loads at the centre of the span. (4). Two concentrated loads at the third points.--This frequently occurs, both from wheel loads of trucks having a wheel base about two-thirds of the span of the beam, but more particularly from the framing of beams shown in Fig. 94, which is very common for floors having columns about 20 ft. apart. Denoting by--W( the total load supported by the main beam, Wd the dead load supported by the main beam, not including any load coming on the column directly, we have, for alternate bays loaded in a beam with an infinite number of spans, as in Fig. 94, and the minimum positive or maximum negative moment is given by M = (2Wd-W, ). Centre Moments In End Bays. These are best obtained from the curves of Figs. 84 to 86. In the case of beams having more than four spans, it is sufficiently accurate to use the curves relating to four spans. In a few cases it is possible to allow a little restraint from the wall columns, but appreciable restraint is very rarely obtained where beams or slabs are built int..