| With the economic structure of our country from extensive to intensive,the recycling of resources and energy saving and environmental protection has been widely concerned in recent years.Our country is in a period of rapid development,the development of infrastructure and other structures built not only consumes a large amount of sand and other natural resources,the old building after the demolition of abandoned construction waste also caused a bad influence on the environment.Recycled concrete recycled aggregate and the waste concrete is formed by crushing,processing and other processes or substitute natural aggregate can realize recovery of waste concrete utilization,solve all kinds of problems brought by the construction waste from the source,not only save the natural aggregate,corrosion solution of aggregate supply and demand contradiction,but also reduces the environmental pollution of the city.Has significant environmental benefits,economic benefits and social benefits.However,due to the difference between the performance and ordinary concrete,especially the seismic ductility is relatively low,so the application of recycled concrete in engineering structure is still low,the application scope is also very limited.The current research work to improve the work ability of recycled concrete is mainly divided into two aspects,one is the main method for materials,carbonization and soak of nanoparticles and other measures to improve the material properties of recycled aggregate;two is the structure,work performance by the steel three surface to improve the confining pressure of recycled concrete.But in the horizontal cyclic loading condition,the periphery of the steel pipe constraint is easy damage,thereby reducing the constraint effect,is not conducive to the protection of the core role of recycled concrete.This paper from the structure,to strengthen the recycled concrete working environment,improve the seismic performance of steel pipe on seismic behavior of the recycled concrete frame concrete core tube structure is studied,the main research contents and achievements areas follows:Firstly,the combination of domestic and foreign research on properties of recycled concrete and recycled aggregate concrete filled steel tube,separately from the components and joints and structure,research status of concrete steel tube were summarized,put forward to provide the performance of recycled aggregate concrete filled steel tube components and joints,process and method of detailed finite element modeling,nonlinear finite element model,and using the existing experimental study to verify the effectiveness of the finite element calculation model of this paper.Secondly,In the aspect of component level,on the basis of the regeneration of concrete through the core of the steel tube,the steel skeleton is added in the core recycled concrete,so as to improve the strength and ductility of the recycled concrete.The plastic damage constitutive geometric nonlinear and recycled concrete is taken into account,with the same steel ratio under different support forms for skeleton parameters,established the I-shaped steel,inner circular steel tube steel pipe,steel reinforcement cage,cross type constraint of four different forms of support beam about recycled concrete column finite element model and through the cyclic loading of the model,and the steel tube concrete and steel ratio under the same increase of recycled aggregate concrete filled steel tube wall thickness of steel pipe are compared,the analysis model of specimen seismic performance.The results show that under the same steel ratio,compared with inner circular steel tube,steel and other cross section structure,steel tube concrete adding I-section steel,bearing greater initial stiffness,ultimate level,seismic performance significantly,and only increase the thickness of steel tube is conducive to the improvement of steel recycled concrete the horizontal bearing capacity,but the ductility has little effect etc..On the basis of this,the P-(35)curves of steel tube steel recycled concrete and steel tube recycled concrete specimens are analyzed,such as axial compression ratio and steel yield strength.Thirdly,at the node form,improve the integrity of the core of recycled concrete based on reducing the node domain through column components,built with stiffening ring welded rigid connections,the new outer tube type single bolt end plate semi-rigid connection,top and bottom square steel tube confined steel three kinds of angle full bolt semi-rigid connection of recycled concrete column and steel beam joint finite element model,the seismic performance analysis model.The results showed that: in the column containing steel support frame,concrete core node domain components through disturbance,the concrete stress strain smaller regeneration core,is conducive to improve the durability of recycled concrete.Compression ratio,stiffness ratio of beam to column under the same axis,with stiffening ring welded rigid joints bearing capacity and hysteretic energy dissipation capacity is higher,but the ductility is relatively poor;the bolt connection of top and seat angle semi-rigid bearing capacity,hysteretic energy is relatively low,good ductility;ultimate bearing capacity,a new coat tube end plate semi-rigid joint hysteretic energy dissipation capacity and ductility performance are good,which is suitable for the engineering application of node.In addition,the influence of P-(35)parameters on the new type of semi rigid joints is analyzed.Fourthly,in the aspect of structural form,the frame core tube is a commonly used high-rise building system in China.The surrounding frame mainly takes the vertical load of the structure,and the core tube improves the flexural capacity of the structure.But the performance of recycled steel concrete under axial compression and eccentric compression is not the same as that of ordinary concrete filled steel tube.There is sufficient experimental basis for taking the vertical load as a peripheral frame system.In this paper,quasi static numerical simulation of horizontal low cyclic loading is carried out with a plane frame and a frame core tube shear wall with 100% recycled concrete replacement rate.The results show that the hysteretic curves of recycled steel concrete column,steel beam frame and frame shear wall specimen are full and spindle shape in the case of outer steel tube confinement and internal steel support.The displacement ductility coefficient of frame is greater than 6,the frame shear wall displacement ductility coefficient is greater than 5,what be good ductility;stiffness and strength degradation is slow;the equivalent viscous damping coefficient of stress frame test piece 0.365,frame shear wall specimens was 0.420;with two specimens of the strength analysis,stiffness degradation law show that the seismic performance of steel reinforced recycled steel reinforced concrete column steel beam frame and frame shear wall structure shows good performance. |
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