Experimental Study Of Seismic Performance Of Recycled Concrete-filled Steel Tube Under Quasi Static Loading

With the development of construction industry,new Bridges,underground structure,port engineering,high-rise,big space,big span structure become important elements in modern infrastructure and buildings,and lots of composite structure has been applied in civil engineering.With the advantages in good mechanical property,anti-seismic performance as well as construction convenience,concrete-filled steel tube structure become more and more popular among civil engineers and the study and application of which are increasingly mature.Growing problems like fast-consumption of building materials as well as the increasing impact of construction waste on the environment etc.make recycled concrete attract more and more eyeballs,for its substitution for normal concrete.In order to reverse the current situation of low application of recycled concrete and seeking the effective way to recycle waste concrete,recycled aggregate concrete-filled steel tube structure becomes another focus for researchers.In recent years,domestic and foreign researchers have done a lot of study on static performance of recycled aggregate concrete-filled steel tube structure,gaining great achievement shown in research findings but still slow in the process of studying dynamic performance,thus comprehensive exploratory research is still underway.This thesis presents below working results based on the study of dynamic performance of recycled aggregate concrete-filled steel tube columns which using 100%recycled coarse aggregate replacement.Nine test specimens were designed according to basic parameters of recycled concrete strength and slenderness ratio,recycled concrete using 100%recycled coarse aggregate replacement were constrained by Q345 high strength seamless round steel tube with 203mm outer diameter and 6mm wall thickness.studying data including damage form,hysteresis characteristics,deformation ability,bearing capacity,stiffness,stiffness degradation,ductility and energy dissipation and analyzing its seismic performance through quasi static test.P-? hysteresis curve appears plump and there is no obvious knead shrinkage phenomenon.The bearing capacity as well as stiffness of test specimens improve as the strength of concrete increases and decline as the slenderness ratio scales up.The experimental results indicates that recycled aggregate concrete-filled steel tube columns possesses good anti-seismic hysteretic performance and energy dissipation.Effective restraining force is formed by high strength steel tube on recycled concrete,refining on weakness of brittle and ductility and increasing its strength.Even if steel tubes has serious buckling or the core of recycled concrete is destroyed,severe strength degradation will not happen.Displacement ductility coefficient of test specimens is between 5.01 to 7.97,and the equivalent viscous damping coefficient is between 0.338 to 0.470.