上海交通大学：《钢筋混凝土基本原理》课程教学资源（PPT课件）Chapter 10 Prestressed Concrete Structure

State of zero stress AP An △PAC State after pre-stressing Ap OPI L Es OPCI

△P △C State after pre-stressing  PⅠ  ES  PCⅠ  L P n P P A A  Ⅰ

L State after pre-stressing △L Consider the loss of prestress caused by concrete shrinkage and creep naA如2-￥，0-为 Ap Grcu=Geu A

State after pre-stressing △L  PⅡ ( ) (1 ) P L E L P L E P L S S         n P PC P A A  Ⅱ   Ⅱ

如果混凝土未开 裂，则由N引起的 应力可以和预应 △L 力叠加，形成最终 的应力状态 Applied by force N △ (钢筋和混凝土共同变形) Es Ec N=OpAp +ocA =oc(An+nAp=Oc Ao Tension stress caused by N force N: 0c= Ao

△ △L   N  P AP  C An  C (_______)  C __ Tension stress caused by force N: A0 N  C   P  n C （钢筋和混凝土共同变形） C C S P E E    An  nAP A0 如果混凝土未开 裂,则由N引起的 应力可以和预应 力叠加,形成最终 的应力状态.  C  P

Zero concrete stress state 注意：受力前后阶段的应力可以叠加 Oc -=0 Outer force: NPo =Open(4o) Steel stress: OPO =OPI+(nOPCI N 外力全部由钢筋承担

 Ⅱ  0  C  PC Outer force: (__) NP0  PCⅡ Steel stress: (_____)  P0  PⅡ  注意：受力前后阶段的应力可以叠加 A0 AP n PCⅡ (__) NP0  外力全部由钢筋承担

Cracking state oc-opcn =f Op=(noc)=om+(nf)-OpI N。=(opcm+(f)》A=Np+(A)

Cracking state C PC t   Ⅱ  f ( (___)) (____) Ncr   PCⅡ  A0  NP0  (____) (___)  P    P0  t nf C n t f A0 f t  PⅡ