In a leaflet issued by the Association of American Portland Cement Manufacturers, H. L. Weber, chief engineer of the Ft. Wayne & Wabash Valley Traction Company, says: "With electric railroads, the question of poles is becoming quite as serious as the tie question; but I believe it will be solved along the line of reinforced con crete a great deal easier than the tie question will be solved along this line. We expect to make renewals with the reinforced concrete pole, and, with this object in view, have made some experiments. Wallace Mar shall, a LaFayette engineer, has also given the matter a great deal of thought. I have the pleasure of giving you the result of his experiments. Mr. Marshall says : " 'In November, 1905, I made a box form of three sides, leaving the top open, for a test pole. It was 35 feet long. The lower five feet was ten inches square ; commencing at that point, it tapered on all sides to five inches at the top. From the five-foot point, I put a tri angular piece in each corner of the form about inches wide at the bottom and 1 inch at the top, to chamfer the corners of the pole. At proper places of a standard line pole for line bracket, cross-arms, and telephone box, I bored holes through the forms, put machine bolts through, and let them extend about two inches in the forms, screwing the nuts the full length of thread. In the top of the form, which was brought to a round point, I placed a pin in the center to leave a hole for an insulator pin. I then filled the form with concrete mixed by hand, consisting of one part cement to six parts ordinary gravel, except a facing of about inch of cement and sand 1 to 3. After covering the bottom of the form about inches, I laid in the large end two 3/4-inch concrete bars 25 feet long, and in the top part two bars lapping them about 4 feet. I left them in the form six days. At the expiration of 30 clays, we tested it as follows: We planted it firmly in the ground five feet deep. At 25 feet distant, we planted a large cedar telephone pole. At the level of 21 feet from the ground, we fastened a wire cable from one pole to the other, which is about the height of a trolley wire. In the center of this cable we suspended a barrel. Into this barrel we loaded steel rivets gradu ally, and watched results. The two poles began to bend as the load was applied. When the two were deflected about 21 inches each toward the other, I observed a small check come in the concrete pole about ten feet from the ground, and simultaneously they appeared from the cable to the ground. We immediately stopped load ing, took off the ballast, weighed it, and calculated the horizontal strain, and found it to be 975 pounds. The maximum moment would be at the ground; but the guess at size we made was about right, since the concrete cracked from ground to cable at almost the same time. When the load was removed, the pole resumed its plumb position, and remains so to-day, although being used for heavy guy wires. The bolts were unscrewed before moving them, leaving the nuts imbedded in the pole. After concrete set, we screwed the bolts into the nuts, and could not loosen them with an ordinary wrench. It took several heavy blows with a sledge hammer. My 'conclusions were, however. that a wire ring or two of reinforcement should be placed about the pin for safety.
" 'Careful estimates were made as to cost of such a pole 35 feet long if made in quantities in proper forms with material at the then market price, and gravel in pit—at $7 actual cost. Comparing that cost with pres ent price of pine poles, and add to the latter the cost of trimming, chamfering, framing, and painting, the con crete pole can be made for less money than the wood, provided no profit is paid a contractor. Figuring the
moments on the pole tested, I found the concrete failed at just about the time the limit of elasticity of the steel was reached, proving that it would be of no value with out the steel. I believe that the concrete pole is practi cable, and the only reason I have not put them to a practical use has been the lack of time to do so,' " Concrete Docks and Piers. Concrete is com ing into more favor year by year for the con struction of docks and piers. With their cost but little more than that of timber, and their length of service beyond estimate, it is no wonder that keen business men realize their value.
A unique concrete dock has recently been fin ished at Cleveland, a city which makes extensive use of the material in many forms (Plate 31). Heavy coal and ore freighters, the largest on the Great Lakes, daily tie up at the clock to unload their cargoes. Provision has been made to take care of the great strains.
The dock is constructed in two sections, north and south, one being 308 feet long and the other 511 feet long. The concrete mass rests on a foundation consist ing of four rows of oak piles. Those in the outer row are 35 feet long, and those on the inner row are 30 feet. The first row is backed by a nine-inch wall of sheet pil ing made of three-inch plank interlocked. The space behind is filled with sand, and faced on top with a three foot layer of stone and crushed slag, upon which the concrete rests. The heads of the piles are embedded in the concrete.
Two oak wales spaced five feet apart are on the face of the dock, forming a buffer for incoming vessels. The upper wale timbers are a foot square, the lower ones being 12 by 14 inches. The dock is provided with cast iron mooring posts set forty feet apart. These are fastened into the concrete by two-inch bolts fitted at the lower ends with washers and square heads. Three rein forcing rods are placed diagonally in the pier under each mooring post. The toe of the pier is also reinforced with bent rods.
A great deal of care has been bestowed on the prob lem of stiffening and anchoring the dock. One and three-eighth-inch rods spaced seven feet apart and eased in piping, tie the lower front and rear wales together. The upper front wale is held in place by one-and-a-quar ter-inch rods spaced five feet centers and cased in pipe. The rear row of piles under the dock carries along its upper end two sixty-pound steel rails bedded in the con crete and running the full length of the pier. These rails serve to stiffen the dock, and also to tie the rear row of piles together.
Resting on these rails every seven feet, is a special casting or saddle to which the anchor rods are fastened. Each anchor rod is connected to the dock by two one and-three-eighths-inch rods, which extend fey twelve feet into the concrete mass, terminating in a washer and nut embedded near the face of the pier.
The dock is anchored by two rows of oak piles located 47 and 77 feet inland. These piles are driven in groups of two, the groups being spaced 7 and 14 feet apart, .center to center, in the outer and inner rows respec tively. They are tied together with steel rails in the same manner as the rear row of piles under the dock. Two rails are used on the inner row, and four on the outer row, of anchor piles. The inner and outer rows are tied to each other by one-and-three-fourth-inch round rods spaced fourteen feet apart, while the outer row is in its turn tied to the dock by one-and-three-fourth-inch and two-inch rods spaced seven feet apart. The ends of the tie-rods are provided with nuts and washers which bear on cast-iron saddles fitting over the steel rails.