Prevention of Vertical End Cracks on Prestressed Beams During Fabrication

Download or read book Prevention of Vertical End Cracks on Prestressed Beams During Fabrication written by Michael Reponen and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The analytical model determined that the variables that have the greatest effect on vertical cracking are atmospheric temperature change between the time of beam casting and the time of strand detensioning, friction coefficient between the casting bed and the bottom of the beams, concrete release strength, beam length, and number of prestressing strands. Beam spacing, and the number of beams on the casting bed have the next greatest effect. Beam spacing becomes more important as the number of beams on the casting bed increases. The number of debonded strands and the lengths of the debonded strands have a small effect on vertical cracking. The conclusion that can be drawn from this research study is that the three most important things to do in order to reduce the occurrence of vertical cracks are to detension the prestressing strands when the atmospheric temperature is similar or warmer than the atmospheric temperature when the beams were cast, to lower the coefficient of friction between the casting bed and the bottom of the beams, and to add additional space between the beams.