Fig1. End of pre-stressed beam Fig.2 anchor position in the end Fig.3 cable position in mid-span
In order to be convenient for construction,three steel cables anchor end of beam,which fits principle of homogeneous disperse and requirement of tension.It will offer much pre-shear force by bending more depth of N1 and N2 in end of beam. The all shown Fig1 and Fig2.
(3):Location and angle of steel cable from other sections. ①Bending shape、angleθ and radius of bending.
Obtain interpolate curve between straight lines.In order to make pre-applied force be perpendicular to
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anchor bearing plate,bending angle of N1, N2, N3 are Radius of each steel cable is:
. ?0?8。
mm RN1?30000mm; RN2?30000RN3?15000mm.
②calculating location of steel stable control points.
Fig.4
Calculation step can be shown example of N3,arrangement figure of bending shown Fig.4
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Calculating horizontal distance between lead point and anchoring point, According to the formula Ld=c·cotθ0,we can have Ld=400×cot8°=2846mm Calculating horizontal distance between lead point and bending point,
According to the formula Lb2=R·tan(θ0/2),we can have Lb2=15000×tan40=1049mm The horizontal distance between bending point and anchoring point is Lw=Ld+Lb2=2846+1049=3895mm
The horizontal distance between bending point and mid-span section is Xk=26660/2+256-Lw=5796mm
The horizontal distance between bending end point lead point is Lb1=Lb2·cosθ0=2098cos8°=2078mm
The horizontal distance between bending end point and mid-span section. =Xk+Lb1+Lb2=5796+2078+2078=9972mm X
According to the same theory,we can get location of control point from N1 and N2,shown following table
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钢束号 升高值c 弯起角 弯起半径支点至锚固弯起点至弯止点至R 点的水平距中截面距跨中截面离 离 -408.84 5794.04 9746.02 水平距离 5850.8 9967.13 11832.6 N1 N2 N3
1610.00 900.00 500.00 8.00 8.00 8.00 45000 30000 15000 156.00 256.00 312.00 ③Calculating location and angle of steel cable from all kinds of sections.
According to the Figure4,the distance point i to bottom of beam ai=a+ci, angle θi. c=100mm.
when(xi?xk)≤0，ci＝0，
ai?a＝100mm；?i＝0
ci?R?R2?(xi?xk)2when0<(xi?xk)≤(Lb1?Lb2)，
?i?sin?1(xi?xk) Rwhen(xi?xk)>(Lb1?Lb2)， ?i＝?0＝8°，
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ci?(xi?xk?Lb2)tan?0
Position and angle of steel table from all cross section
计算截面 钢束xk 编号 La+Lb xi-xk θ c ai=a+c 跨中截面xi=0 N1 N2 N3 未0.00 -408.84 6259.64 为负值，5794.04 4173.09 弯起 9746.02 2086.55 -408.84 6259.64 7073.84 5794.04 4173.09 870.958 9746.02 2086.55 为负值 -408.84 6259.64 10038.8 5794.04 4173.09 3835.96 8.00 1.66 0.00 8.00 7.35 0.00 100.00 L/4截面xi=6665 N1 N2 N3 变化点截面N1 xi=9630 N2 551.86 12.65 0.00 968.35 246.25 651.86 112.65 100.00 1068.35 346.25 14