In redundancy structure , the structure ' s distortion and strain will change along with time because of creep . according to the characteristic of concrete ' s creep , the creep grows quickly in the concrete " earlier age . for the long of bridge ' s construction period , the concrete ' s age of different part are discrepantly 在超静定结构中，结构的变形和内力都会因徐变而随时间不断变化，对于实际的工程结构，结构的整体总是分阶段建造起来的，某些荷载(如自重)也是在结构建造过程中分阶段作用在不断生长的结构上的。
