T-BEAM BRIDGES.-Details of a reinforced concrete T-beam bridge with a 30-ft. span, as designed by the Ohio State Highway Department are given in Fig. 4. Data are given for 16-ft. and 20-ft. roadways. Tar felt is used for expansion joints. Details of a reinforced concrete T-beam bridge, with 28-ft. span and 18-ft. roadway as designed by the Michigan State Highway Department are given in Fig. 5. This bridge is designed to carry an 18-ton road-roller. Data and quantities for reinforced concrete T-beam bridges designed by the Massachusetts Highway Commission are given in Table IV. The bridges were designed for a 20-ton motor truck with axles spaced 12 ft. and 6-ft. gage, with 14 tons on rear axle and 6 tons on front axle, and uniform load of 100 lb. per sq. ft. Bridges have a clear roadway of 23' 6" and a distance out to out of 27' 8", with allowable stresses as given in Report Joint Committee, Am. Soc. C. E., 1913. Stirrups in. sq. spaced 6 in. to 8 in. in end quarters, and 12 in. to 18 in. in middle half were used in beams 10-ft. to 28-ft. span; stirrups in. sq. spaced 8 in. to 10 in. in end quarters; and 16 in. to 24 in. in middle half in beams of 34-ft. to 40-ft. span. One-half of horizontal bars, or one-half of number of horizontal bars less one, are bent-up, not more than two bars being bent up at one place. Points of bending up are about one-eighth of span apart. Bent-up longitudinal bars are anchored at the ends of the beams by means of hooks bent through 180 degrees. Details of standard reinforced concrete T-beam bridges designed by U. S. Bureau of Public Roads are given in Fig. 6 and Fig. 7. The plans in Fig. 6 are for spans from 16 ft. to 26 ft., inclusive, and a 20-ft. roadway; while plans in Fig. 7 are for spans from 28 ft. to 40 ft., inclusive, and a 20-ft. roadway. Dimensions, data and quantities for the different spans are given in detail. These girder bridges are designed for a 15-ton truck, with axles spaced 10 ft. centers, and FIG. 4. 8-10" STEEL LIST 16 FT. ROADWAY Bar Size L'ath to. Wt. 219-033 533 17-8 33 496 33-819 306 7-522 78 7-239 134 35-6 3 362 35-6 3 362 36-3 2 247 K 36-3 2 247 20 FT. ROADWAY Bar Sizel 'gth No. Wt. A 2" 23-433 655 B221-8 33 608 C33-8 23 370 7-5 22 78 72 52 179 35-6 4 483 35-64 483 D E F1 H1 36-3 2 247 ESTIMATED QUANTITIES 16 ft. Roadway 20 Ft. Roadway Concrete 35.2 cu.yd. Rein. steel 5880 16. Cement 51 bbl. 41.9 cu. yd. 7185 16: 612 ból. Estimate does not include road metal Note:- Workmanship and mat's conform to "Genl. Spec. For Concrete and Reinf. Concrete Structures", State Highway, Dept. of Ohio. Concrete 1-2-4 mix. Reinf. bars to be sq. tw. or equiv. def. bars except stirrups may be plain sq. STANDARD CONCRETE BEAM BRIDGE OHIO STATE HIGHWAY DEPARTMENT REINFORCED CONCRETE T-BEAM BRIDGE. OHIO STATE HIGHWAY DEPARTMENT. wheels spaced 6 ft. centers. Two-thirds of the total load is carried on the rear axle. An impact allowance of 30 per cent is provided for. Concrete is 1:2:4 mixture with agregate 1 in. maximum. Allowable tension in steel reinforcement, 16,000 lb. per sq. in.; allowable compression in concrete, 650 lb. per sq. in.; allowable shear on concrete, 110 lb. per sq. in. TABLE IVA. QUANTITIES IN CONCRETE DECK GIRDER HIGHWAY BRIDGES. U. S. BUREAU OF PUBLIC Roads. DATA AND QUANTITIES, FOR REINFORCED CONCRETE T-BEAM BRIDGES. Roadway 23 ft. 6 in. Designed for 20-ton Motor Truck. The U. S. Bureau of Public Roads has also prepared standard plans for the same spans with 16-ft. roadway, 18-ft. roadway, and 24-ft. roadway. Quantities of concrete and reinforcing steel in concrete deck girders with 16-ft., 18-ft., 20-ft., and 24-ft. roadway are given in Table IVa. Deck concrete girders with 16-ft. roadway have 4 beams, with 18-ft. and 20-ft. roadway have 5 beams, with 24-ft. roadway have 6 beams. |