N3 9746.02 2086.55 为负值未0.00 弯起 0.00 100.00 支点截面N1 N2 N3 -408.84 6259.64 13738.8 5794.04 4173.09 7535.96 9746.02 2086.55 3583.98 8.00 8.00 8.00 1488.09 764.04 356.17 1588.09 864.04 456.17 xi=13330 (4)The position and angle in flat bend zone
N1, N2, N3 are in the same plane at the middle span, but at anchor terminal they are all in the middle
lane, to get this result, N2、N3 must be bend from both sides to the middle line in the main beam lab. N2、N3 are take the same to bend up, and the position in flat bend as Fig. Shows. There are two curve arc, each angle is
638180??4.569?. 8000???15
16
3)Requirement for non-prestressed reinforcement
To be satisfied with the ultimate limit state, the number of non-prestressed reinforcement are:
After deciding the reinforcement number, non- prestressed reinforcement is decided according to the normal cross-section’s ultimate limit state.
Assume the distance from prestressed and non-prestressed reinforcement’s resultant force point to the cross-section bottom is a=80mm,so h0?h?a?1800?80?1720mm
Assume first kind of T shape beam, according to ?0Md?fcdbf'x(h0?x/2), we can get the depth of compressive zone x 1.0×5934.5×106=22.4×2200x(1720-x/2)
x= 71.5mm Select 5Φ18mm HRB400 As=1272.5mm2 ,lay out one line,space is 75mm. as = 45mm,shown following Figure. 17 6. Calculation of geometric features of main beam cross-section . 分块面积A 跨中截面 ai至梁顶的距离yi 对梁顶端自身惯性矩 的面积距 469700000 0 -19617150 450082850 469700000 0 19929913.04 0 489629913 476180000 0 293551888315.92 0 0 293551888315.92 302841784485.01 0.00 0 0 302841784485.01 310015240144.94 0 yu-yi -16.25 -1232.04 -1132.04 16.04 -1199.76 -1099.76 0.00 14.86 -1241.14 ix=ai*(yu-yi)2 212248387.4 0 截面惯性矩 577.0181039 804000 584.2039801 0 -11539.5 792460.5 1800 1700 567.96 -14788136703 -14575888316 278976000000.00 150231.5567 2590963026 2056102257 0 4647215515 193343252.8 0 307489000000.00 804000 584.20 0 11723.48 0 815723.5 1800 1700 0 600.24 876000 544 0 1800 18 11723.48 0 887723.5 分块面积A 1700 0.00 558.86 L/4截面 ai至梁顶的距离yi 19929913.04 0 496109913 0 0 310015240144.94 -1141.14 0.00 15266416602 0 15459759855 ix=ai*(yu-yi)2 146696923.3 0 325475000000.00 截面惯性矩 对梁顶端自身惯性矩 的面积距 469700000 0 -17445766.94 452254233.1 469700000 0 17723910.87 0 487423910.9 476544000 0 292921224809.63 0 0 292921224809.63 293726037745.95 0 293726037745.95 310663690406.96 yu-yi -13.50773333 -1229.303753 -941.1341567 13.33173373 -1202.464286 -914.2946896 0 12.78138854 -1243.218611 804000 584.2039801 0 -11539.5 792460.5 1800 1511.830403 570.6962468 -10220921733 -10074224810 282847000000.00 142899039.9 0 9800063214 0 9942962254 143106770.4 0 303669000000.00 804000 584.2039801 0 11723.48 0 815723.5 1800 1511.830403 0 597.5357138 876000 544 0 1800 19