Point 4.—­In this case it would seem that the author has put a wrong interpretation on what is generally meant by shear.  However, it is undoubtedly true that actual shear in reinforcing steel is sometimes figured and relied on.  Under some conditions it is good practice, and under others it is not.  Transverse rods, properly placed, can surely act in transmitting stress from the stem to the flange of a T-beam, and could properly be so used.  There are other conditions under which the concrete may hold the rods so rigidly that their shearing strength may be utilized; where such conditions do not obtain, it is not ordinarily necessary to count on the shearing strength of the rods.

Point 5.—­Even if vertical stirrups do not act until the concrete has cracked, they are still desirable, as insuring a gradual failure and, generally, greater ultimate carrying capacity.  It would seem that the point where their full strength should be developed is rather at the neutral axis than at the centroid of compression stresses.  As they are usually quite light, this generally enables them to secure the requisite anchorage in the compressed part of the concrete.  Applied to a riveted truss, the author’s reasoning would require that all the rivets by which web members are attached to the top chord should be above the center of gravity of the chord section.

Point 6.—­There are many engineers who, accepting the common theory of diagonal tension and compression in a solid beam, believe that, in a reinforced concrete beam with stirrups, the concrete can carry the diagonal compression, and the stirrups the tension.  If these web stresses are adequately cared for, shear can be neglected.

The writer cannot escape the conclusion that tests which have been made support the above belief.  He believes that stirrups should be inclined at an angle of 45 deg. or less, and that they should be fastened rigidly to the horizontal bars; but that is merely the most efficient way to use them—­not the only way to secure the desired action, at least, in some degree.

The author’s proposed method of bending up some of the main bars is good, but he should not overlook the fact that he is taking them away from the bottom of the beam just as surely as in the case of a sharp bend, and this is one of his objections to the ordinary method of bending them up.  Moreover, with long spans and varying distances of the load, the curve which he adopts for his bars cannot possibly be always the true equilibrium curve.  His concrete must then act as a stiffening truss, and will almost inevitably crack before his cable can come into action as such.