1、从张拉端至计算截面的曲线孔道部分切线的夹角之和(rad);k孔道每米局部偏差对摩擦的影响系数,取k=0.0015;预应力筋与孔道壁的摩擦系数,取=0.25。当预应力筋为直线时Pp=P2)、P=conAn(锚下端部张拉力P=Pq)con预应力筋张拉端的控制应力con=0.70fpk(Nmm2);A每束预应力筋的截面面积(139mm2);n同时张拉预应力筋束数;Pq预应力筋张拉端的张拉力。3)、Pz=Pqe-(kx+)Pz经过长度X后预应力筋的终点处张拉力(N);4)、L=(PpX)/(ApEp)L理论伸长值(m);X预应力筋相应的长度(m);Ap钢绞线的截面积(139mm2);Ep预应力筋的弹性
2、模量(1.95105Mpa)。3、张拉伸长量控制及读数计算方法:实际伸长量要扣除拉力(10%)后的理论计算值4、30m箱梁各钢束理论伸长量计算如下:钢束布置断面图如图所示,从上至下依次为N2、N5、N1、N3、N4。钢束根数布置:根据图纸设计布置。40米T梁钢束引伸长量:如伸长量计算表如下图所示,管道分段示意图:浈江大桥预制T梁预应力伸长量计算表(1)、该计算表适用于第一联第14孔、第5孔右幅6及7号梁,第二联第68孔、第9孔右幅7号梁econ(Mpa)Ai(mm2)kEg(Mpa)锚具变形、钢筋回缩取6mm(一端)。预应力张拉时还要考虑钢束与锚圈口之间的摩擦损失,锚口摩阻损失暂按3%考虑,即
3、钢束锚外控制应力为1437Mp,锚口摩阻损失的具体数据应由试验确定,或者采用厂家及施工单位常年积累的数据,任何时候,锚外张拉控制应力不得超过0.8fpk(该内容为图纸要求)2.718313021390.250.0015195000N1分段n束数Ay(mm2)L或x(m)曲线段孔道切线夹角(rad)kx+e-(kx+)起点力Pq(kN)终点力Pz(kN)精确计算方法全梁理论伸长量(mm)设计理论伸长量(mm)平均张拉力Pp(kN)各段理论伸长量AB811125.70000.0000.0090.9911447.8241435.4981441.6520.038230.861230.800BC12.2
4、17070.1220.0490.9521367.0331400.9870.079CD1.81500.0030.9971363.3171365.1740.011合计:0.128N1(10%初应力)144.782143.550144.1650.00425.651136.703140.0990.008136.332136.5170.0010.013N2中梁4.30500.0060.9941438.5051443.1590.029230.241230.2001369.8971403.9213.19900.0050.9951363.3391366.6150.020N2中梁(10%初应力)143.8501
5、44.31625.582136.990140.392136.334136.6620.002N2边梁912511628.8021618.3181623.5541541.1341579.4121533.7571537.442N2边梁(10%初应力)162.880161.832162.355154.113157.941153.376153.744N3中梁2.91000.9961441.5181444.6690.019229.630229.6001372.7661406.8624.58400.0070.9931363.3601368.058N3中梁(10%初应力)144.152144.46725.51
6、4137.277140.686136.336136.806N3边梁1621.7081625.2521544.3621582.7201533.7801539.065N3边梁(10%初应力)162.171162.525154.436158.272153.378153.906N41.47400.9981625.2051627.0030.010228.993229.0001547.6921586.1336.00901533.8051540.7380.127N4(10%初应力)162.520162.70025.444154.769158.613153.380154.074N5(左右)9732.24001
7、266.8461262.5971264.7200.015228.300228.4005.67206.50.1130.0370.9641216.8931239.60411.77300.0180.9821195.5921206.2110.075N5(左右)(10%初应力)126.685126.260126.47225.367121.689123.960119.559120.6211:设计图纸要求:混凝土强度及弹性模量达到设计值的85%,且龄期不少于7d后,方可张拉预应力钢束。两端对称、均匀张拉,采用张拉力和引申量双控,钢束张拉顺序为N2N5N1N3N4,钢束伸长量为扣除初应力(10%)后的理论计算
8、值。2:该计算表适用于第一联第14孔、第5孔右幅6及7号梁,第二联第68孔、第9孔右幅7号梁,(2)、该计算表适用于第一联第5孔左幅7及6号梁,第二联第9孔左幅7号梁68349.37000.0140.9861085.8681070.7131078.2730.062174.177170.0004.88700.9631030.9191050.6900.0320.48400.9991030.1711030.5450.097108.587107.071107.82719.353103.092105.069103.017103.055N27.36300.9891073.9411079.894173.5546.10900.0400.9611032.1341052.8991.25801030.1881031.1610.096N2(10%初应力)107.394107.98919.284103.213105.290103.019103.116N35.96801076.1911081.022172.932168.0001034.2961055.105
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