Effect ofprestressingindex
Fig. 11 shows theload-deflectionofbeamsB1,B2andB3with
prestressing indicesof0,70and100,respectivelyandaverage
concrete compressivestrengthequalto72MPa.Thecracking
loads ofthespecimensB1andB2werelowerthanB3by
53% and9%,respectively.Thisisduetotheprestressingforce
effect, whichconcludesthatthecrackingloadsincreaseby
increasing theprestressinglevel.Themaximumloadsofspec-
imens B1andB2werehigherthanB3by13%and10%,
respectively. Theslightdifferenceinthefailureloadisattrib-
uted tothelittlevariationinthedesignedcrosssectionofpar-
tially, fullyandnon-prestressedconcretebeamsbasedonthe
commercially availableprestressedandnon-prestressedrein-
forcement inEgypt.Themaximumdeflectionatthefailure
load ofspecimensB1andB2werehigherthanB3by223%
and 239%,respectively.Thisisduetothepresenceofnon-pre-
stressed steel,whichismoreductilethantheprestressing
reinforcement.