The Cracking Control Concept And New Designing Method Of Reinforced Concrete Structure

Lots of engineering practices and laboratory experiments indicate that normal reinforced concrete (R.C.) structure doesn't have good mechanical performance and large using range, which is caused by cracks develop unlimitedly. If we want to improve mechanical performance of normal R.C. structure (NS for short), we must search efficient cracking control method. Based on concept of"resistance", the traditional prestressed structure make concrete get prestressing force, has solved the problems of NS successfully. At present, all of R.C. structures with long span choose pestressed form.The item which is named"study on designing theory of composite R.C. structure based on fracture mechanics"and supported by national nature and science funds has putted forward two new cracking control concepts,"prevention"and"release", and also putted forward two new structures, composite R.C. structure strengthaned with GFRP (CS for short) and composite R.C. structure based on concepts of"prevention"and"release"(PRS for short).The item has carried out study on mechanical performance of CS and PRS with simple reinforcement steel, which indicates that CS and PRS has better anti-crack capability, rigidity, bearing capacity and shearing performance than NS.This thesis carried out study on mechanical performance of CS and PRS with high tensile reinforcement steel, experimental results also made sure CS and PRS had better mechanical performance than NS. At the same time, the thesis did nonlinear FEA for the whole loading process of CS.In addition, combining traditional cracking control method, the thesis putted forward another two new structures, R.C. structure based on concepts of"release"and"resistance"(RRS for short), composite R.C. structure based on concepts of"prevention","release"and"resistance"(PRRS for short); then did theoretical analysis and experimental study on RRS and PRRS. Results indicate the two new structures have successfully solved the weak anti-crack capability of NS, they can be designed for full prestressed form;and enhance structural rigidity and durability. Comparing with prestressed structure; the construction procedure and counting process is simper; the loss of prestress is litter. Besides those advantages, the two new structures have more cracks that develop slowly after cracking, get over many defects of traditional prestressed structure, such as, after cracking its performance reduces rapidly, cracks develops swiftly, and has nothing signs when it is destroyed.The three cracking control concepts and four new structures in this thesis provide new ways for designing R.C. structure, which have important theoretical value and practical significance.