ELMPLEB OF MASONRY OR PLAIN-CONOZETZ Pizza.
Fig. 141 shows the form for a plain concrete or masonry pier for highway and electric railway bridges, and Table 82 gives the dimensions for various spans.* New York Central Pier. Fig. 142 shows the standard pier employed by the New York Central and Hudson River Rail road for piers 40 ft. high or less.t The up-stream end is the same as the down-stream, except where the stark-water is necessary. The coping and the stark-water cap are made of 1 : 1 : 2 portland cement concrete, and the remainder of the pier of 1 : 3 : 6. Items 5, 6, 8, and 9 of the specifications for standard abutments (see the second paragraph of § 1076) apply also to the piers. For square crossings and spans of 40 ft. or less, the width on top, A, is 4 ft., and it increases 6 inches for each 20-ft. increase in the length of the span up to 100 ft., and then the same amount for each 25-ft. increase up to 250 ft. If the pier is more than 30 ft. high, it has a corbel course under the coping; or, in effect, the pier has one coping as shown, and upon that another coping which projects 4 inches.
Fig. 143 shows the dimensions of a stone-block masonry pier of the Illinois Central Railway's single track bridge over the Ohio River at Cairo, Ill. This pier stands between two 523-foot spans, and stands upon a bed of sand of in definite depth. This is the pier that was used in the computations referred to in § 1097.
Fig. 144 shows a plain concrete bridge pier built on the Atchison, Topeka, and Santa Fe Railway System in an uninhabited mountain region of New Mexico.* The pier stands between two 100-foot plate girders. The stream is ordinarily dry, but is subject occasionally to severe floods.
City, Mexico and Orient Railroad. Fig. 145 shows the outlines of one of several concrete piers for a railroad plate girder bridge on the Kansas City, Mexico and Orient Railroad; and Fig. 146 and 147 show, the method of constructing the forms for the shaft of the pier.* For the cost of these piers, see $ 1110.
The curved ends of these piers were made by smooth wood forms; but often the form is made polygonal, and a sheet of ,thin steel is nailed on the inside of the wood form to give a uniform curvature and a smooth surface.
Cost of
Piers. Below is the cost of the piers shown in Fig. 145-47. The piers were sunk in coffer-dams made of wood sheet piles through 12 to 18 feet of sand to bed rock. The concrete was mixed on shore by machinery, and placed in dump boxes on push cars which ran by gravity to the pier. The concrete for the base of the pier was deposited in the coffer-dam.
The cost per cubic yard of concrete was as follows: •