Analysis Of The Basic Mechanical Properties Of Recycled Concrete Filled In Steel Tube After High Temperature

Every year our country bring about lots of waste concrete, the concrete bringnegative effect to the ecological environment. So how to make the concrete usingcircularly has urgent and practical significance for ecological, environmentalprotection and sustainable development of the society. Recycled concrete is the re-useof the waste concrete, after crushing, cleaning, classifing the waste concrete, it is usedas aggregate to make concrete again. Compared with common concrete, the strengthand the elastic modulus of the recycled concrete are lower than the same mixproportion common concrete, which makes its mechanical properties, durability,deformation ability lower than ordinary concrete, this became the biggest obstacle toapply and popularize recycled concrete in structural engineering. In practicalengineering the recycled concrete application level is relatively low currently, it ismainly used for non-stress or smaller stress structures, such as roadbed backfill and soon. However, the recycled concrete has better property of temperature lag andresisting high temperature compared with ordinary concrete, these features make itsmechanical properties loss little after high temperature; and the steel has regular andclose metallurgical structure, which make its mechanical property can restorebasically after high temperature. So some scholars consider to combine the recycledconcrete and the steel tube to form recycled concrete filled in steel tube member, thiscan effectively improve the mechanical property after high temperature, and the steeltube’s "hoop" effect to the core concrete can remedy the defects of the recycledconcrete’s poor mechanical property. At present the recycled concrete filled in steel tube study is mainly about the mechanical property at normal temperature here andabroad, the study on the mechanical property and member’s working mechanism afterhigh temperature is just started and the reference documentation is few. Therefore,this paper adopt test and finite element model to explore the mechanical property andworking mechanism of the recycled concrete filled in steel tube after high temperature,the specific contents are as follows:1. Details the characteristics, development and research status at home and abroad ofthe related topics including concrete filled in steel tube, the recycled concrete,recycled concrete filled in steel tube, illustrates the research method, content, purposeand significance of this article;2. Do axial compression test about17recycled concrete filled in square steel tubeand6recycled concrete filled in circular steel tube short columns after constant hightemperature, to inspect the different temperatures, different coarse aggregatereplacement ratios, different cross section forms’ influence to the bearing capacity;3. On the basis of determining the constitutive relation of the steel and recycledconcrete after high temperature, establish the finite element model the same with thetest by ABAQUS, compare the ABAQUS results with the experimental results,verified the correctness of the axial compression model built in this paper, tounderstand the mechanics property of the recycled concrete filled in steel tube afterhigh temperature comprehensively, establish the different size axial compressionmodel, analyse the influence of temperature and substitution rate, and the mechanicalproperties and working mechanism of the recycled concrete filled in steel tube afterhigh temperature, finally by regression analysis of a large amount of data, deduces theultimate bearing capacity’s simplified calculation formula of the recycled concretefilled in steel tube short columns which in axial compression after constant hightemperature, and verify it;4. Establish the eccentric compression model of recycled concrete filled in steel tubeafter high temperature using finite element simulation software ABAQUS. First, setup the same eccentric compression model with the test in document n, compare thecalculated results with the test’s results, and verify the eccentric compression finite element model of this paper. Then, establish the eccentric compression model whichthe size same with chapter3, compare and analyze the influence of the differenteccentricity ratio, temperature, replacement ratio, slenderness ratio of the recycledconcrete filled in steel tube after high temperature, and analyze the stress performance.Finally, derived the bearing capacity’s simplified calculation formula of the recycledconcrete filled in steel tube short columns after constant high temperature through theregression analysis of a large amount of data, and verify it;...