CYLINDER PIERS

All quantities for One Pair of Tubes Piles

Diam Weight per Vert- Ft. of 2 Tubes Cu-Yd No-For

of 3" Tube 16

16

7"

8 16

One

Per Z VertFt Tube 15" 75 97 119 142 164 187 0-0911 18 88 114 140 167 194 220 0-1311 21 102 131 162 194 223 253 0-178 1 24 117 150 185 221 255 290 0-2321 27 130 167 206 247 284 324 0-296 1 30 143 185 227 271 315 357 0-3641 33 157 203 250 300 347 393 0-4401 36 172 222 273 326 377 429 0-524 2 39 185 240 293 352 408 463 0-614 2 42 200 257 316 378 437 497 0-712 3 45 213 275 339 405 469 532 0-820 3 48 227 293 362 412 500 568 0.930

54

60

66

72

78

84

329 405 485 563 636 1-178 5 365 449 539 621 705 1-454 6

495 593 684 780 1-758 7

538 643 743 845 2-094 8

698 805 917 2-458 10 749 866 984 2-850 13

MINIMUM DIAMETER OF

17-0

STEEL TUBULAR PIERS

18-0

FOR A HEIGHT OF 15 FEET

19-0

TO CARRY A SINGLE SPAN

20-0

9-311-312-614-615-317-9

PIER BRACING

FIG. 18. STEEL TUBULAR PIERS FOR HIGHWAY BRIDGES. AMERICAN BRIDGE COMPANY.

Where piers are founded on rock, the tubes are to be anchored to the rock and then filled with concrete. Or cribs may be sunk on the rock and the tube set in a pocket in the crib and resting on the rock. The space outside the tube is then filled with concrete and the tube is filled with concrete in the usual manner.

Cylinder Piers for Highway Bridge, Trail B. C.*-Steel cylinder piers, Fig. 19, were used for a steel highway bridge designed by Waddell and Harrington, consulting engineers, and built across the Columbia River at Trail, B. C. The main spans are 172 ft. 8 in. long and are carried on piers made of two steel cylinders filled with concrete. The steel cylinders are 9 ft. in diameter

* Engineering News, Dec. 5, 1912.

17-6"

1

at the bottom and 6 ft. in diameter at the top, and are 86 ft. long. The cylinders are made of plates in. thick and are connected by a double plate web diaphragm, each diaphragm made of-in. plates spaced 24 in. apart and 25 ft. high, and reaching from below low water to above high water. The diaphragms were covered and filled with concrete. The cylinders are spaced The piers were sunk by the pneumatic process.

21 ft. centers.

WOOD PILE ABUTMENTS

SHORT TRUSS SPANS 16-0"ROADWAY
lowa Highway Commission

This abutment to be used only for spans 35' to 65' inclusive.
Superstructure to be steel low truss with joists and wood floor to be used as shown.
Joists are to be punched for spiking pieces. Under ordinary conditions distance from
grade to natural ground line at abutment shall not exceed 7-0". Double thickness
of floor plank is recommended for heavy traffic. Use cast iron ogee or malleable
washers under heads and nuts of all wood bolts.

FIG. 20.

TIMBER PILE ABUTMENT FOR STEEL HIGHWAY BRIDGES. IOWA HIGHWAY
COMMISSION.

Timber Abutment.—The details of a timber abutment for steel low truss highway bridges, as designed by the Iowa Highway Commission are shown in Fig. 20. This abutment is to be used for steel low truss bridges with timber floor with spans of 35 ft. to 65 ft. This abutment is especially suited to crossings of drainage ditches where it is difficult to get satisfactory foundations for masonry abutments.

Specifications for abutments and piers are given in Appendix II.

Reference. For details of abutments and piers for railway bridges, see the author's "Structural Engineers' Handbook."

CHAPTER XXI.

DESIGN OF REINFORCED CONCRETE BRIDGES.

Introduction.-The design of slab and girder bridges will be discussed in this chapter. The design of culverts will be considered in Chapter XXII, and the design of arches in Chapter XXIII.

SLAB BRIDGES.-The distribution of concentrated loads on reinforced concrete slabs has been considered in Chapter IX. The floor of a slab bridge is designed as any simply supported slab for a span length equal to the span length of the bridge. Shear in the slab should be investigated and stirrups and bent-up bars should be provided where necessary. Both the straight longitudinal and bent-up bars should be hooked at the ends. The slab bridge has the advantage that it is simple in design, and requires less material and labor in building the forms and less labor

in placing the reinforcement than any other type of concrete bridge. It also admits of widening the roadway without impairing the strength of the existing structure. It has the disadvantage that it is not economical of materials for spans of more than about 20 ft. Details of a reinforced concrete slab bridge having a 16-ft. span and a 20-ft. roadway are shown in Fig. 1. This bridge was designed to carry a 15-ton road roller. This bridge is designed to be carried on independent abutments. Quantities of concrete and steel in standard slab bridges designed by the Wisconsin Highway Commission are given in Table I.

TABLE I.

QUANTITIES OF CONCRETE AND STEEL IN REINFORCED SLAB BRIDGES.
WISCONSIN HIGHWAY COMMISSION.

Details of a reinforced concrete slab bridge resting on reinforced concrete abutments are shown in Fig. 2. The slab is designed to support the tops of the abutments and to take the thrust of the filling. As the bridge is designed it will act as a simple span resting on the tops of the abutments. The Wisconsin Highway Commission has prepared standard plans for this type of bridge for spans of 8 ft. to 24 ft., and for roadways of 16 ft., 18 ft., 20 ft., and 24 ft. Data on spans with 20-ft. and 24-ft. roadways are given in Table II.

TABLE II.

DATA ON CONCRETE SLAB BRIDGES ON REINFORCED CONCRETE ABUTMENTS.
WISCONSIN HIGHWAY COMMISSION.

Abutment slab 5 ft. above footing in 6-ft. span, 6 ft. above footing in 8-ft. span and 7 ft. above footing in other spans. For details of a bridge with 16-ft. span and 20-ft. roadway, see Fig. 2.

Details of a standard concrete slab bridge designed by the Iowa Highway Commission are given in Fig. 3. These bridges are designed with an 18-ft. roadway, and with spans of 14 ft. to 24 ft. Data for the design and quantities of concrete and steel are given in Fig. 3. Three layers of tar paper are put between the slab and the abutment to make an expansion joint.

Standard reinforced concrete bridges of the Iowa Highway Commission are designed for a 15-ton traction engine with two-thirds of total load on rear axle, or 100 lb. per sq. ft. of roadway and sidewalks. Each rear wheel is assumed as distributed 6 ft. transversely and 5 ft. longitudinally. For thin slabs on girders the same wheel load is assumed as distributed 4 ft. transversely and 4 ft. longitudinally. Allowable stresses in lb. per sq. in. are: compression in concrete, 600; shear in concrete, 100 (as a measure of diagonal tension); tension in steel 16,000.

For design of a slab bridge see Fig. 19.

Data for floor slabs designed by the Ohio State Highway Department are given in Table III.