Part 12 (1/2)

Mr Russell states that the writer scarcely touched on top reinforceitudinal rods in columns, unless the reinforcement were stiff members Mr Russell's remarks, to the effect that coluned as framed structures, point to the conclusion that structural beams and columns, protected with concrete, should be used in such cases If the ruling ners were uniformly to use what is most appropriate in each particular location and not to carry out some system, this is just ould be done in many cases; but some minds are so constructed that they take pleasure in such boasts as this: ”There is not a pound of structural steel in that building” A broad-ineer will use reinforced concrete where it is most appropriate, and structural steel or cast iron where these arehis clients' funds to carry out soht appreciates the writer's idea, for the paper was not intended to criticize soh” or which ”answers the purpose,” but to systematize or standardize reinforced concrete and put it on a basis of rational analysis and co has been or is being placed on, by a careful weeding out of all that is irrational, senseless, and weak

Mr Chapineer has never used such methods of construction as those which the writer condeh; whether or not those who use theineers is beside the question

As to the ability of the end connection of a stringer carrying flange stress or bendingconsiderable overhanging loads with no better connection Even wide sidewalks of bridges sometimes have tension connections on rivet heads

While this is not to be co which n were on as loose a basis as reinforced concrete

Mr Chapman assu 3 shows a se He does not sho vertical stirrups can relieve a beam of the shear between two of these stirrups

The criticiss 5 and 6, is that there is not enough concrete in the sterip the aripped in that stem, because it does not run to the support or beyond it for anchorage Steel ned in violation of many of the require of rivets, size of lattice bars, etc; the bridge will not necessarily fail or shoeakness as soon as it is put into service, but it is faulty and weak just the saineer does not findthat the negative moment is double the positive moment, because he considers the live load either on one span only, or on alternate spans” It is just in such ineer” is inconsistent If he is going to consider the beams as continuous, he should find the full continuous beam moment and provide for it It is just this disposition to take an advantage wherever one can be taken, without giving proper consideration to the disadvantage entailed, which is condeineer” will reduce his bending e fraction, because of continuity, but he will not reinforce over the supports for full continuity Reinforcement for full continuity was not recommended, but it was intie is taken of continuity in reducing the principal bending moment

Mr Chapman says that an arch should not be used where the abutments are unstable Unstable is a relative and indefinite word If hebut rock, even such a foundation is only quite stable when the abutment has a vertical rock face to take horizontal thrusts If arches could be built only under such conditions, few of them would be built Some settlement is to be expected in almost any soil, and because of horizontal thrusts there is also a tendency for arch abutments to rotate It is this tendency which opens up cracks in spandrels of arches, andline, commonly made by the elastic theorist, absolute foolishness

Mr Beyer has developed a novel explanation of the way stirrups act, but it is one which is scarcely likely to irder to which he refers, which has neither web plate nor diagonals, but only verticals connecting the top and bottoirder has been considered by Aineers rather as a curiosity, if not a monstrosity If vertical stirrups acted to reinforce little vertical cantilevers, there would have to be a large nument of the beam would be insured reinforcement

The writer is utterly at a loss to knohat Professor Ostrup raphs He says that in the first point two designs are n, whatever it is, he lays at the writer's door in these words: ”The author's second design is an invention of his ohich the Profession at large is invited to adopt” In the first point sharp bends in reinforcing rods are conde is said of ”a reinforced concrete beaed in the shape of a rod, with separate concrete blocks placed on top of it without being connected”

In reply to Professor Ostrup, it should be stated that the purpose of the paper is not to belittle the irip of concrete on steel, but to point out that the wonderful things this grip is supposed to do, as exhibited by current design, will not stand the test of analysis

Professor Ostrup has shown a new phase of the stress in shear rods He says they are in bending between the centers of compressive resultants

We have been told in books and reports that these rods are in stress of some kind, which is iven of designing stirrups for bending If these rods are not in shear, as stated by Professor Ostrup, how can they be in bending in any such fashi+on as that indicated in Fig 12?

Professor Ostrup's analysis, by which he attempts to justify stirrups and to show that vertical stirrups are preferable, merely treats of local distribution of stress from short rods into concrete Apparently, it would work the same if the stirrups nores the vital question of what possible aid the stirrup can be in relieving the concrete between stirrups of the shear of the beais a concrete example Soirders at the coluh they were separated at their ends by about 1-1/2 or 2 ft, the space between the girders The beams had 1-1/8-in tension rods in the bottom At the supports a short 1/4-in rod was used near the top of the beam for continuity Does this need any comment? It was not the work of a novice or of an inexperienced builder

Professor Ostrup's re of the neutral axis of a beam and of the pressure line of an arch are based on theory which is grounded in impossible assumptions The materials dealt with do not justify these assu theory based thereon

His platitudes about the danger ofreinforcement in an arch are hardly warranted If the depth and reinforcee-end theory would dictate, as against the elastic theory, it will strengthen the arch just as surely as it would strengthen a plate girder to thicken the web and flange angles

The writer's complaint is not that the theories of reinforced concrete are not fully developed They are developed too highly, developed out of all comparison with the materials dealt with It is just because reinforced concrete structures are being built in increasing nuineers to inject sons, and drop the idea that ”whatever is is right”

Mr Porter has much to say about U-bars He states that they are useful in holding the tension bars in place and in tying the slab to the steitimate functions for little loose rods; but why call them shear rods and make believe that they take the shear of a bea as dowel pins, the writer has already referred to this subject Answering a query by Mr Porter, it may be stated that ould counteract the horizontal cleaving force in a beam is one or more rods curved up to the upper part of the beam and anchored at the support or run into the next span Strangely enough, Mr

Porter co, as advocated in the paper The excellent results shown by the test referred to by him can well be contrasted with soned for 250 lb per sq ft When that load was placed on it, the deflection was more than 1 in in a span of 20 ft No rods were curved up and run over the supports It was a stirrup job

Mr Porter intimates that the correct reinforced concrete column may be on lines of concrete mixed with nails or wires There is no doubt but that such concrete would be strong in co in tension, but a colu eleitudinal rods, but their office is to take tension; they should not be considered as taking co remark: ”It is a well-known fact that the bottom chords in queen-post trusses are useless, as far as resistance to tension is concerned” The writer cannot think that he means by this that, for exa-rod would be just as good with the rod omitted If queen-post trusses are useless, soht cars could be dispensed with

Mr Goodrich misunderstands the reference to the ”only rational and only efficient design possible” The staten which would be adopted, if slabs were suspended on rods, is the only rational and the only efficient design possible If the counterfort of a retaining ere a bracket on the upper side of a horizontal slab projecting out froround, the horizontal slab being heavily loaded, it is doubtful whether any engineer would think of using any other sche from slab to wall and anchored into each This is exactly the condition in this shape of retaining wall, except that it is underground

Mr Goodrich says that the writer's reasoning as to the sixth point is al in pure shear

The joke, however, is on the experi in shear They have failed to point out that, in every case where great strength in shear is manifested, the concrete is confined laterally or under heavy compression normal to the sheared plane

Stirrups do not confine concrete in a direction normal to the sheared plane, and they do not increase the co-bone fashi+on would confine the concrete across diagonal planes, but such a design would be wasteful, and the coest their office in this capacity