The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . R2=w(c-|-*)X^=4c 4c {c+xy -iwl which is also the shearing force at Cfor that position of the load. Asthe load travels, the shear at thehead of the train will be given bythe ordinates of a parabola havingits vertex at A, and a maximumP,n„^l at B. If the loadFig. 41. travels the reverse way, the shearing force at the head of the train is given by the ordinates of the dottedparabola. The greatest shear at C for any position of the load occurswhen the head of the train is at C. For any load p betw
The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . R2=w(c-|-*)X^=4c 4c {c+xy -iwl which is also the shearing force at Cfor that position of the load. Asthe load travels, the shear at thehead of the train will be given bythe ordinates of a parabola havingits vertex at A, and a maximumP,n„^l at B. If the loadFig. 41. travels the reverse way, the shearing force at the head of the train is given by the ordinates of the dottedparabola. The greatest shear at C for any position of the load occurswhen the head of the train is at C. For any load p between C and Bwill increase the reaction at B and therefore the shear at C by partof p, but at the same time will diminish the shear at C by the whole. T 4 •-f i Fig. 42. of p. The web of a girder must resist the maximum shear, and,with a travelling load like a railway train, this is greater for partialthan for complete loading. Generally a girder supports both a deadand a live load. The distribution of total shear, due to a dead loadWl per ft. run and a travelling load Wi per ft. run, is shown in fig. 42,arranged so that the dead load shear is added to the maximumtravelling load shear of the samesign. 24. Counierbracing.—In the case ofgirders with braced webs, the tensionbars of which are not adapted toresist a thrust, another circumstancedue to the position of the live loadmust be considered. For a train ad-vancing from the left, the travellingload shear in the left half of the spanis of a different sign from that due tothe dead load. Fig. 43 shows themaximum shear at vertical sectionsdue to a dead and travelling load, thelatter advancing (fig. 43, a) from theleft and (fig. 43, 6) from the rightabutment. Comparing the figures i
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
