Study On Impact Resistant Behavior Of Recycled Aggregate Concrete-Filled Steel Tubular Members

Recycled aggregate concrete-filled steel tube (RACFST) consists of steel tube and core recycled aggregate concrete (RAC). RACFST not only takes advantage of steel tube and RAC but also makes up for their respective shortcomings. Filling RAC into steel tube can promote the reuse of waste concretes and further protect the natural aggregate resources, thus can also resolve the environmental and related social issues in waste concrete processing. RACFST members will be used more and more popularly as bridge piers and building columns due to their excellent structural and constructional performance, however, bridge piers and building columns may be inevitably subjected to the impact of moving objects (e.g. car and boat) or explosion during their whole life, which will affect the safety of structure and even lead to the collapse of an entire structure. It is very important to study the impact resistant performance of RACFST members for their rational application in practical engineering.To investigate the performance of RACFST members under lateral impact loads, the following experimental and theoretical studies were carried out:(1) The research works, including the dynamic mechanical properties of concrete and steel, the behavior of RACFST members and the impact resistant performance of normal concrete-filled steel tubular members, were reviewed.(2) A series of tests on16RACFST members and6concrete-filled steel tube members subjected to lateral impacts were carried out to investigate the effect of recycled coarse aggregate replacement ratio, drop height and axial compressive force on the impact resistant performance of the tested specimens.(3) Based on the analysis of the test results, a finite element analysis (FEA) model was developed, in which the effect of recycled coarse aggregate replacement ratio and strain rate on the constitutive relationship of core RAC was considered.(4) The impact resistant capacity of the tested specimens was predicted by the bearing capacity calculating method of normal concrete-filled steel tubular beam-columns in design codes. It is shown that, compared with the experimental results, all the predicted impact resistant capacities tend to be safe.