下弯

• The tendons in the top and the base plate have an effect , namely “ opposite tension ” , on the web . moreover , it is found that the web prestressed reinforcement is necessary since it is capable of lowering the principal tensile stress . the reinforcement arrangement without the web prestressed reinforcement is not mature in theory since its disadvantages are not solved in practice
  底板索和顶板索对腹板存在着明显的“对拉”作用,同时,下弯索有效的克服了腹板的主拉应力,设计中是不可少的,不设置下弯索的布索方案在理论上还不够成熟,实践证明该布索方案也存在着许多的弊端。