| Title |
An Experimental Study on Lap Splice Performance and Development Length of Untensioned Prestressing Strand |
| Authors |
Ha Sang-Su ; Choi Jun-Young ; Lee Moon-Sung |
| Keywords |
Bond Stress ; Untensioned Prestressing Strand ; Embedment Length ; 9.3mm Strand ; 12.7mm Strand |
| Abstract |
In this study, to replace 7-wire strand for reinforcement steel, it was attempted to devise connection detail which made workability improvement and confirmed effective stress transfer in the region of the precast concrete connection. However, the bond characteristics of the untensioned strand in concrete differed from those of the reinforcement steel and prestressing strand. An investigation was conducted to determine the effect of the development length and lap splice performance. The pullout test variables included diameter of strands (9.3mm, 12.7mm), embedment lengths, and embedded shapes (straight, 90°hook). Based on the pullout test results, The maximum bond stress at the 9.3mm and 12.7mm strands decreased with the increase of the rate of bond length. The untensioned strand displayed bond performance when secure embedment length was more than 70% of the development length of the modified deformed bars equation (ACI 318 Building code, 2005). The development length of standard hook for untensioned prestressing strands can be determined in accomplice with the provisions suggested for conventional deformed bars. Moreover, to verify the lap splice performance of the untensioned strand, the beam was made of U-shaped 7-wire strands which were embedded in the bottom of the half PC beam. The lap splice performance test variable included embedded length. On the basis of the test result, To promise the sufficient lap splice performance, the appropriate lap splice length was proposed. |