【正文】 　　　　　　　　　τ=計算纖維面積距剪應力τ正應力σ主應力正應力　　　第一階段凈面積Sn第二階段凈面積S39。o第三階段凈面積SoσtpσcpNpⅡ=epn=aaσcx=x0x0204657417主應力　　　bbσtp　　　　　　　　σcp　　　　　　　　截面面積矩計算第一階段凈截面對其重心軸（重心軸位置x=）第二階段凈截面對其重心軸（重心軸位置x=）第三階段凈截面對其重心軸（重心軸位置x=）　　　　　截面類型　　　　　計算點位置aax0x0aax0x0aax0x0　　　　　面積局符號SnaSnx0S39。oaS39。0x0S0aS0x0　　　　　面積距239266511264139987　　　　　　aax0x0　　　　　　　　　Vq=　　　　　　　　　　τ=　　　　　　　　　正應力　　　計算纖維面積距剪應力τ正應力σ主應力NpⅡ=　第一階段凈面積Sn第二階段凈面積S39。o第三階段凈面積Soσtpσcpepn=　σcx=　aa239266511主應力　　　x0x0264139987σtp　　　　　　　　　σcp　　　　　　　　　　　　　　　　　　　　　　由以上可知混凝土主壓應力最大值為*fck　　　　　由以上可知混凝土主拉應力最大值為　　　　　　　　　　　　　　　　The limit value of concrete principal pressive stress is , from the upper table, concrete principle pressive stress all lower the limit value, so its ok!check of principle stressWe know the maximum tension stress is 10. Check of crackingcracking check of normal section in short term Check midspan cross section:calculation of concrete prepressive cracking caused by prestressMidspan cross section: We have:calculation of concrete tensile stress caused by loadWe have concrete normal stress cracking For A type concrete structure, concrete tensile stress should satisfied with the following in short term: (C)The result satisfied with the request! Ok!!!in long term: ok!!!!racking check of inclined section in short term Take changing point section as an calculation section.principle stressTake aa as an exampleShear stress:剪力SnS39。0S0Ib第一項第二項第三項256100198372000205824900137432000+1120023700209028000217848900153368000+11200210600224376000230929600159696000+11200198372000205824900137432000+11200求和（剪應力）2. Normal stressNpIIynbapepnAnInI39。0I0ynay39。0ay0aMG1MG21MG22+MQl正應力3801716505792455+11+11+1127329725610983000001017000007740000003801716505792455+11+11+1127329725610983000001017000007740000003801716505792455+11+11+112732972561098300000101700000774000000Principal tensile stressPrinciple tensile stress calculation table in changing point section計算纖維SnS39。0S0剪應力正應力主拉應力主壓應力aa198372000209028000224376000x0x0205824900217848900230929600bb137432000153368000159696000(2)limit value of principle tensile stressThe concrete principle tensile stress limit value in short term:According to the upper table, we know its meet the requirements. 11. Deformation calculate1) check of main beam deflection in short termL= C50 concrete elastic modulus: Take L/4 section’s as the average value.Simply supported beam’s deflection check formula is: (1) deflection caused by variable actionDeflection coefficient of main beam midspan: , variable load value in short Term is: . So the deflection caused by variable action is:Deflection caused by variable action that considered the long term load:（2）deflection caused by the first and second stage dead load in long term2) arch value caused by prestressUse L/4 section’s torque as the average of the beam:So the arch value is:The upper arch value caused by prestress that considered long term loading is :3） layout of prearch valueThe total deflection of beam is: There is no need to layout the prearch value.12. Local pressive calculate in anchor zoneAccording to the analysis to three prestressed cables anchor point, N2 is the critical cable, the anchor and reinforcement layout in beam end of N2 are shown in the following.Some size are revised as following: d=80mm。 the squire side length is 200, and diameter of cable is 230.1)Size of local pressionLocal pression size meet the requirement of the concrete crack resistance:。2)Calculation of local pressure bearing capacityThe formula of local pressure bearing capacity is:concrete core area, 。indirect influence coefficient, k=indirect reinforcement volume ratio,So the local pression meet the requirement.