Numerical Analysis On The Seismic Resistance Of Steel Tube Columns Filled With Recycled Aggregate Concrete

With the rapid economic development, the modernization and urbanization level of China have improved continuously, civil engineering construction developed advance rapidly as well, at the same time, civil engineering construction in China has produced a lot of construction waste and caused serious environmental pollution. How to process the growing community of construction rubbish efficiently has drawn extensive attention. The study found that both at home and abroad, it has an effective way to handle demolished concrete, which is demolished concrete is broken into recycled aggregate and then recycled aggregate can be used to replace natural aggregate partly or wholly for preparing recycled concrete.Regarded as a combinatorial materials, recycled aggregate concrete filled steel tube with properties of two components such as high strength, lightweight, convenient construction, good ductility performance and so on show a greatly application prospect. Two difficult problems have been solved at the same time by recycled aggregate replaced natural aggregate, one is the exhaustion of natural aggregate resources, and the other one is plenty of unwieldy waste concrete. So the way of waste concrete disposal has captured public attention. Up till the present moment, the study on recycled concrete filled steel tube structure mainly concentrated on axially compressive capacity of short columns, fire resistant performance and eccentric compressive performance. But the research is not perfect on the ductility performance, energy dissipation and horizontal bearing capacity of recycled concrete filled steel tube structure. Hence, based on the obtained experimental data, the author has established a reasonable finite element model for recycled aggregate concrete filled steel tube columns by nonlinear finite element software ABAQUS6.11. The following conclusions are obtained by numerical simulation in this paper.(1) Recycled aggregate concrete filled steel tube Column has good ductility performance under quasi-static cyclic loads. The displacement ductility of recycled aggregate concrete filled steel tube Columns increased in different degrees with the recycled aggregate replacement rate increasing. According to the experimental data and a large number of numerical calculations, a simplified formula on displacement ductility of recycled aggregate concrete filled steel tube Columns has been proposed.(2) Effects of different parameters on the horizontal bearing capacity of recycled concrete filled steel tube columns are investigated. The axial load ratio and steel ratio are the most critical factors which affect the horizontal bearing capacity of the recycled concrete filled steel tube columns. The larger the axial load ratio, the lower the horizontal bearing capacity and seismic resistance of the recycled concrete filled steel tube columns; but this pattern is reversed when the steel ratio increases. In addition, the steel ratio is also an important factor which influences the initial flexural stiffness of the recycled concrete filled steel tube columns.(3) For the same concrete strength, the horizontal bearing capacity of the recycled concrete filled steel tube columns decreases with the increase of recycled aggregate replacement percentage, but the displacement ductility of the recycled concrete filled steel tube columns is opposite.(4) The initial stiffness of recycled aggregate concrete filled steel tube Columns decreases distinctly with recycled aggregate replacement percentage increasing. The numerical analysis indicates that initial stiffness of component with r=100%(the r indicates recycled aggregate replacement percentage) is down17.1percent compared with that of r=0%. But the effect of recycled aggregate replacement percentage on stiffness of component decreases with the increase of cyclic number.(5) The mechanical properties of recycled aggregate, such as strength, hardness and so on are not better than that of nature aggregate, so the energy dissipation capacity of the recycled concrete filled steel tube columns linearly decreases with the increasing of recycled aggregate replacement percentage, the numerical analysis indicates that the total energy dissipation capacity of component with r=100%is down11.3percent compared with that of r=0%.