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11 (24.5 ft) 7.5 m Selected portion for testing 18.3 m (60 ft) Figure 3. Modeled portion of the prototype bridge. bridge. The specimens were constructed and tested in an ically, the overall seismic performance of the structure and the inverted position, and the girder ends were simply supported. performance of the connection details of the pier cap-to-col- The column in each specimen was first subjected to low- umn connection and the pier cap-to-girder connection regions. level loads to simulate service loads. Then, the column was subjected to cyclic loading to simulate the effects of earth- 2.4.2 Design Details quake loads on the corresponding prototype structure, specif- For the specimen column diameter of 2 ft., the required reinforcement ratio of 2 percent resulted in longitudinal steel Vertical load of 20 reinforcing bars, 19 mm (3/4 in.) in diameter. The result- Lateral load ing design for the plastic hinge region, to provide the required volumetric ratio, was a #10 (#3) spiral with a pitch of 63 mm 610 mm (24 in.) diameter (2.5 in.). The clear concrete cover provided outside the lon- reinforced concrete (RC) column gitudinal reinforcement was 1 in., as shown in Figure 5a for (8'-2 5/8") 2505 mm Steel wide-flange SPC1. The connection region in SPC2 differed slightly, as girder shown in Figure 5b, because of the use of mechanical anchor- Horizontal reaction beam age for the column longitudinal bars. A moment-curvature Steel box beam analysis was performed to predict the behavior of the plastic hinge region of the column. The same column design was used for both SPC1 and SPC2. (a) Elevation In specimen SPC1, 610 101 (W24 68) rolled shapes were used for the four girders. The girders were decreased to Roller supports 460 60 (W18 40) rolled shapes in SPC2. Horizontal reaction beam Steel box beam The 610 mm (24 in.) depth of SPC1 girders corresponds to Roller supports RC slab a depth of 1,830 mm (72 in.) for the prototype bridge. This is larger than the typical girder depth for bridges with spans 1016 mm comparable to the prototype bridge. This depth was selected (3'-4") Steel diaphragm to provide adequate development length for the column lon- gitudinal bars inside the connection region of the test speci- 3760 mm 1016 mm (12'-4") 610 mm (24 in.) dia. (3'-4") RC column men. For SPC2, the 457 mm (18 in.) girder depth corresponds to 1,370 mm (54 in.) in the prototype bridge. This depth is 1016 mm representative of actual bridges of span comparable to that of (3'-4") Steel girder the prototype bridge. The depth of the connection region in SPC2 was not sufficient to fully develop the column longi- 5800 mm tudinal bars inside the connection region. The ends of the col- (19'-0") 6100 mm umn bars were threaded and mechanical anchorage, in the (20'-0") N form of nuts threaded at the column bar ends, was added to provide full anchorage for these bars. (b) Plan view Grillage model analyses were performed to predict the Figure 4. General configuration of the test specimen. force-displacement responses of SPC1 and SPC2. A nonlinear