Two precast girders with welded splices were tested as simply supported beams to determine the resistance of the splices to shear. The girders consisted of thin web channels assembled by welding to produce members of a hollow section. The addition of six Inclined bars on each side of the welded splices in Tee-Head No. 3 resulted in a marked increase in the shear resistance of the specimen as compared with Tee-Head No. 2 which contained no inclined stirrups.
Four box girders with lap welded splices were tested to determine the effect of rotation of eccentrically loaded lap welded reinforcing bars on the lateral rigidity of the splice and precast thin-shelled concrete framing members. Each specimen was made of six precast thinshelled elements that were welded and spliced together to form a hollow box girder 1-by 2-ft in cross section and 8 ft 10 in. long. These girders were used to compare the relative rigidities of lap welded splices with and without transverse reinforcement.The comparative results of flexural tests of these girders indicate that there was little difference in the observed lateral displacements up to stresses in splices of about 35,000 psi.However, at higher stresses, the lateral movement of the end portion of the girders and the concrete surrounding the splices was significantly greater in the girders which contained no transverse reinforcement .
Five specimens representing grout pocket assemblies used to protect welded joints in precast concrete panels were subjected to 250 cycles of freezing and thawing in order to determine the effectiveness of epoxy/Thiokol adhesives when applied to the surfaces of grout pockets prior to grouting. The specimens of plain concrete were cast in two halves and were 14-by 14-by 2 5/8 in. in size when placed together. The resulting grout pocket was 8 1/4 in. square at the top surface and 1 5/8 in. deep. The sides of the pockets were cast at an angle of 45°w ith the horizontal so that the bottom of the pocket was a 5 in. square. The sides and bottom of four of the specimens were coated with various epoxy/ Thiokol adhesive compounds just prior to grouting.The fifth specimen was used as a control specimen and was not coated. The specimens were frozen in air at a temperature of 2 ± 1°F, and were thawed in a water bath at a temperature of 77 ± 1°F. The control specimen failed after 96 cycles of freezing and thawing while no visible damage was apparent in the coated specimens after 250 cycles. These results clearly indicate that the use of epoxy/Thiokol adhesive mixtures significantly increases the durability of grout pocket assemblies by improving the bond between the grout and the hardened concrete.
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