The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . Fig. 71. BRIDGET—BRIDGETT 557 as shown in fig. 72 with arcs of the length h, k, h, &c., and with theradii ri, rs, &c. (note, for a length \h at each end the radius will beinfinite, and the curve must end with a straight line tangent to thelast arc), then let v be the measured deflection of this curve from thestraight line, and V the actual deflection of the bridge; we haveV = o»/6, approximately. This method distorts the curve, so thatvertical ordinates of the curve are drawn to a scale b times gre
The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . Fig. 71. BRIDGET—BRIDGETT 557 as shown in fig. 72 with arcs of the length h, k, h, &c., and with theradii ri, rs, &c. (note, for a length \h at each end the radius will beinfinite, and the curve must end with a straight line tangent to thelast arc), then let v be the measured deflection of this curve from thestraight line, and V the actual deflection of the bridge; we haveV = o»/6, approximately. This method distorts the curve, so thatvertical ordinates of the curve are drawn to a scale b times greaterthan that of the horizontal ordinates. Thus if the horizontal scalebe one-tenth of an inch to the foot, 0 = 120, and a beam 100 ft. inlength would be drawn equal to 10 in.; then if the true radius atthe centre were 10,000 ft., this radius, if the curve were undistorted,. would be on paper 1000 in., but making 6 = 50 we can draw the curvewith a radius of 20 in. The vertical distortion of the curve must notbe so great that there is a very sensible difference between the lengthof the arc and its chord. This can be regulated by altering the valueof 6. In fig. 72 distortion is carried too far; this figure is merely usedas an illustration. 38. Camber.—In order that a girder may become straight underits working load it should be constructed with a camber or upwardconvexity equal to the calculated deflection. Owing to the yieldingof joints when a beam is first loaded a smaller modulus of elasticityshould be taken than for a solid bar. For riveted girders E is about17,500,000 lb per sq. in. for first loading. W. J. M. Rankine givesthe approximate rule Working deflection = S = Plio,oooh,where I is the span and ft the depth of the beam, the stressesbeine those usual in bridgework, due to the total dead and liveload (W. C. U.) BRIDGET, SAINT, more properly Brig
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
