The shaded rectangles represent the distribution of shear due to the load at C, while no may be termed the datum line of shear.
In very short girders the shear must be computed, and in long girders the deflexion, particularly the flexure from the variable load, since a flexure of more than of the length is liable to crack the plastering of the ceilings carried by the girders.
The same necessity for computing shear and flexure applies to the floor beams. The floors between the girders are constructed of " I" beams, spaced generally about 5 ft.
As before in § 31, the rotation may be resolved into a shear-pair, in planes perpendicular to Ox and Oy.
X near the middle of the girder the shear changes sign, according as the load advances from the left or the right.
It is customary to pluck the wool by hand rather than shear it, as this is believed to ensure a finer second crop. Black-faced and Cheviots are also found in some places.
Of p. The web of a girder must resist the maximum shear, and, than for complete loading.
The distribution of total shear, due to a dead load w 1 per ft.
42, arranged so that the dead load shear is added to the maximum travelling load shear of the same sign.
For a train advancing from the left, the travelling load shear in the left half of the span is of a different sign from that due to the dead load.
Beyond C, the shear at C will probably be greatest when W2 is at C. Let R be the resultant of the loads on the bridge when W 1 is at C. Then the reaction at B and shear at C is Rn/l.
Next let the loads advance a distance a so that W2 comes to C. Then the shear at C is R(n+a)/l - WI, plus any reaction d at B, due to any additional load which has come on the girder during the movement.
The shear will therefore be increased by bringing W2 to C, if Ra/l+d >W 1 and d is generally small and negligible.
46) be the section at which the greatest shear is required, and let the loads advance from the left till W I is at C. If R is the resultant of the loads then on the girder, the reaction at B and shear at C is Rn/l.
But the shear may be greater when W2 is at C. In that case the shear at C becomes R(n+a)/l+d - WI, if a>p, and R(n+a)/l+d - W I a/p, if a WI in the first case, and if Ra/l >W l al p in the second case.
Such a line has for abscissa the distance of a load from one end of a girder, and for ordinate the bending moment or shear at any given section, or on any member, due to that load.
Repeating the process for other positions, we get the influence line Aghb, for the shear at C due to unit load anywhere on the girder.
Clearly, the distribution of the load by the rail girder considerably alters the distribution of shear due to a load in the bay in which the section considered lies.
Generally, the greatest shear S at C will occur when the longer of the segments into which C divides the girder is fully loaded and the other is unloaded, the leading load being at C. If the loads are very unequal or unequally spaced, a trial or two will determine which position gives the greatest value of S.
The greatest shear at C' of the opposite sign to that due to the loading of the longer segment occurs with the shorter segment loaded.
Run the shear at C is w X the area of the influence curve under the segment covered by the load, attention being paid to the sign of the area of the curve.
Similarly, rs = W (x +a) 11 is the shear on DB.
If Israel alone among nations can meet the Assyrian with the boast "with us is God," the reason is that in Zion the true God is known' - not indeed to the mass, but to the prophet, and that the "holy seed" 2 or "remnant" (contained in the name Shear yashubh) which forms the salt of the nation.
Ray's translation of that work (p. 334), stating that it is "a Sea-fowl, which fishermen observe to resort to their vessels in some numbers, swimming 1 swiftly to and fro, backward, forward and about them, and doth as it were radere aquam, shear the water, from whence perhaps it had its name."
It was formerly sheared to short lengths and formed into piles, which were then rolled out, perhaps to be resheared and rerolled into bars, known as " single shear " or " double shear " steel according to the number of sheaiings.
The twist or surface-shear being proportional to the torque, the horse-power can be calculated if the modulus of rigidity of the steel employed is known or if the amount of twist corresponding to a given power has previously been ascertained by direct experiment on the shaft before it has been put in place.
It was not peculiarly connected with Mecca; at Taff, for example, it was customary on return to the city after an absence to present oneself at the sanctuary, and there shear the hair (Muh.
The greatest shear at C may occur with W I at C. If W 1 passes FIG.
The effect of the ends of the wire is, as Ewing remarks, to shear the diagram in the horizontal direction through the angle which the sloping line makes with the vertical.
The total shear at a b is S = R-E(W1+W2 ...) where the summation extends to all the loads to the left of the section.
The greatest shear at C for any position of the load occurs when the head of the train is at C. For any load p between C and B will increase the reaction at B and therefore the shear at C by part of p, but at the same time will diminish the shear at C by the whole FIG.