By these tests it is seen that, in a beam, bars without hooks were stronger in their hold on the concrete by an average of 13% than those with hooks.  Each test of the group of straight bars showed that they were stronger than either of those with hooked bars.  Bars anchored over the support in the manner recommended in the paper were nearly 40% stronger than hooked bars and 20% stronger than straight bars.  These percentages, furthermore, do not represent all the advantages of anchored bars.  The method of failure is of greatest significance.  A failure by tension in the steel is an ideal failure, because it is easiest to provide against.  Failures by slipping of bars, and by cracking and disintegrating of the concrete beam near the support, as exhibited by the other tests, indicate danger, and demand much larger factors of safety.

Professor Clifford, in criticizing the statement that a member which cannot act until failure has started is not a proper element of design, refers to another statement by the writer, namely, “The steel in the tension side of the beam should be considered as taking all the tension.”  He states that this cannot take place until the concrete has failed in tension at this point.  The tension side of a beam will stretch out a measurable amount under load.  The stretching out of the beam vertically, alongside of a stirrup, would be exceedingly minute, if no cracks occurred in the beam.

Mr. Mensch says that “the stresses involved are mostly secondary.”  He compares them to web stresses in a plate girder, which can scarcely be called secondary.  Furthermore, those stresses are carefully worked out and abundantly provided for in any good design.  To give an example of how a plate girder might be designed:  Many plate girders have rivets in the flanges, spaced 6 in. apart near the supports, that is, girders designed with no regard to good practice.  These girders, perhaps, need twice as many rivets near the ends, according to good and acceptable practice, which is also rational practice.  The girders stand up and perform their office.  It is doubtful whether they would fail in these rivet lines in a test to destruction; but a reasonable analysis shows that these rivets are needed, and no good engineer would ignore this rule of design or claim that it should be discarded because the girders do their work anyway.  There are many things about structures, as every engineer who has examined many of those erected without engineering supervision can testify, which are bad, but not quite bad enough to be cause for condemnation.  Not many years ago the writer ordered reinforcement in a structure designed by one of the best structural engineers in the United States, because the floor-beams had sharp bends in the flange angles.  This is not a secondary matter, and sharp bends in reinforcing rods are not a secondary matter.  No amount of analysis can show that these rods or flange angles will perform their full duty.  Something else must be overstressed, and herein is a violation of the principles of sound engineering.