| With the development of China's construction industry,the performance requirements of concrete in terms of strength and durability gradually increase.In addition,the development and utilization of building energy to a large extent will lead to serious environmental pollution.Therefore,the use of new concrete and new materials has become an important way to improve the quality of building in the future.During the development of coal mines,gangue is a serious waste material generated in the process.According to the data,if we extract 1 hundred million tons of coal in a year,the amount of coal gangue will be 14 million tons.In the development of coal mines,the energy and natural environment are also damaged.In addition,with the rapid development of concrete preparation and construction technology,mineral admixtures have become an important part of cementitious materials.Among them,silica fume filled the gap between cement well,and the compressive and wear-resistant properties of concrete improved considerably.Adding fly ash into concrete can save a lot of cement,improve the workability of concrete,and improve the pump ability of concrete.Therefore,the amount of coal gangue is replaced by the natural stone in concrete,and the addition of fly ash and silica fume at the same time can effectively alleviate the environmental and ecological problems caused by the accumulation of mineral waste,but also reduce the demand for the natural raw materials in the construction industry,reduce the cost,and save the national energy.It is imminent to study the structure of coal gangue concrete.After consulting a lot of literatures,it is known that there is very little discussion on the bearing capacity of coal gangue self compacting concrete steel tube short columns under axial compression.Therefore,on the basis of the experiment,the discussion of coal gangue type self compacting concrete steel pipe short column is carried out.The main contents are as follows:the proportion of coal gangue to replace natural stone is 15%,35%,55%respectively.The proportion of fly ash equivalent to cement quantity is 10%,20%,30%respectively,and the proportion of silica fume to replace cement is 5%to carry out coagulation.The influence of different dosage on the working performance and mechanical properties of coal gangue self compacting concrete and coal gangue concrete,and the effect on the ultimate bearing capacity of short columns of gangue type self compacting concrete filled steel tube and coal gangue concrete steel tube short columns,and the amount of the same coal gangue,fly ash and silica fume are studied.The ultimate bearing capacity of gangue self compacting concrete filled steel tubular short columns and gangue concrete-filled steel tubular columns is compared.The ANSYS software is used to compare with the test value,and the accuracy of the ANSYS analysis of the bearing capacity of the bearing capacity of the coal gangue self compacting concrete filled steel tube short column is discussed.The main research results are as follows:(1)Performance:for the coal gangue self compacting concrete,unchanged fixed cementitious materials,coal gangue from 15%-55%in the process of change,the slump of concrete expansion becomes smaller,the Tsoo value gradually increased,L type flow meter test value is less than 1,and gradually become smaller;when to improve the content of coal gangue to 55%,individual test value is less than 0.80,while steel passing capacity is relatively low,can not meet the requirements of self compacting concrete.Fixed coal gangue,fly ash from the 10%-30%process,concrete slump and expansion degree increased as the amount of fly ash increased,Tsoo decreased.(2)Mechanical properties:for the coal gangue self compacting concrete,with the change of the amount of coal gangue from 15%-55%,the compressive strength of the cube,the axial compression strength and the modulus of elasticity gradually decrease with the increase of the amount of coal gangue,from 35%to 55%under the condition of constant cementitious material.The strength and modulus of strength and elastic modulus of the gangue concrete mixed with 15%are between 15%and 35%of the coal gangue type self compacting concrete.Under the condition of constant mixing of coal gangue,the cube compressive strength of coal gangue self compacting concrete and coal gangue concrete,axial compression strength and modulus of elasticity are under the condition of unconfined pressure,with the amount of fly ash content from 10%-30%,it increases first and then decreases,but the decrease is less than the increase.This paper combines the working performance and mechanical properties of third and fourth chapters of coal gangue self compacting concrete.The optimum mix ratio of coal gangue type self compacting concrete is considered as C-GSCC1 group.(3)Short column test:with the increase of the amount of coal gangue,the ultimate bearing capacity of steel pipe short column gradually decreases,and the axial displacement becomes larger,and the ultimate bearing capacity of the short column with the amount of coal gangue which is 55%than the coal gangue is 35%,and the displacement is greatly changed.For the analysis of the coal gangue self compacting concrete and the short column of the gangue concrete steel tube,it is found that with the increase of the amount of fly ash,the ultimate bearing capacity of the short column of the steel pipe first rises and then decreases,and the load displacement can be seen that the increase of the bearing capacity is greater than the reduction.With the increase of the amount of fly ash,the axial displacement becomes smaller and then becomes larger.Through data analysis,it is known that the displacement change of fly ash is 20%,which is larger than that of 30%.In addition,through the study of the calculation method of the bearing capacity of short columns of different countries,the bearing capacity of the shaft core of the coal gangue self compacting concrete short column is obtained,and compared with the test value,the design and construction regulations of the steel tube concrete structure(CECS28-2012),the design and construction regulations of the steel pipe concrete structure(JCJO1-89)the calculation result of the bearing capacity of Cai Shaohuai is partial to safety and is in agreement with the test results.On this basis,a modified formula for the ultimate bearing capacity of the coal gangue type self compacting concrete steel pipe short column is obtained.Combining with the self compacting concrete construction technology,the construction technology of coal gangue self compacting concrete is discussed,and the key control points of construction and the measures of strengthening the technical quality are put forward.(4)The average value of the ratio of ANSYS to Nu is 1.024,the coefficient of variation of the ratio is 0.019,the deviation between NA and Nu is about 2.40%,and the result of the test is in good agreement with the simulation result of the finite element.It shows that ANSYS finite element simulation analysis of the feasibility of axial compression bearing capacity of coal gangue self compacting concrete steel tube stub columns. |
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