Prediction Model for Development Length of Indented Prestressing Wires

摘要

A study was conducted to determine the effect of prestressing steel indentation types and concrete release strength on development length and flexural capacity of pretensioned members. Thirteen different indented 5.32 mm (0.209 in.) diameter prestressing wires were used to cast prisms with a square cross section (3.5 x 3.5 in. [88.9 x 88.9 mm]). Different concrete release strengths of 3500, 4500, and 6000 psi (24.13, 31.03, and 41.37 MPa) were obtained to test the effect of concrete release strengths on the development length. All prisms were tested in three-point bending at different spans to estimate development length. Lastly, a design equation was developed based on experimental data for prediction of development length for 5.32 mm (0.209 in.) diameter indented prestressing wires. Experimental results indicated that indentation type has a large impact on development length. Tests on specimens with different concrete release strengths indicated that the concrete compressive strength at detensioning had less effect on long-term moment capacity of sections using prestressing wires with deep indent patterns.