铁路桥的简支梁在自重和运营荷载作用下,一般是下缘受拉、上缘受压.为了抵消荷载产生的拉应力,在受拉区事先施加压力,造成预压应力。这种预压应力叫做“预应力”。施加了预压应力的钢筋混凝土梁简称为预应力混凝土梁。与普通钢筋混凝土梁比较,预应力钢筋混凝土梁具有许多优点,是当前的发展方 Under the action of self-weight and operating load, simply supported beams of railway bridges are generally tensioned at the lower edge and pressed at the upper edge. In order to counteract the tensile stress generated by the load, prestressing stress is exerted in the tensioned zone in advance. This pre-stress is called “pre-stress.” The prestressed concrete beams are referred to as prestressed concrete beams. Compared with ordinary reinforced concrete beams, prestressed reinforced concrete beams have many advantages, is the current development side