Test study on size effect of short-term stiffness at using stage of flexural members

Many researches on size effect of quasi-brittle materials have been carried out. But experiment combining with RC structures is not sufficient. At present, design values in rules and regulations are mainly based on experimental results of small size test samples, which exist different from practical engineering structures. Meeting structural normal using function is a basic principle of structural design. In the process of designing and checking to deformation, calculating short-term stiffness at using stage is the most important. This paper based on observing experimental phenomenon and analyzing test data, evaluating size effect on short-term rigidity at using stage of RC flexural members. Obtaining size modify relation to correlation calculation formula. This research provided reference for practical engineering design.