| The accumulation of coal gangue causes serious pollution and waste of land.Using coal gangue instead of concrete aggregate can not only solve the problems of environmental pollution and land waste,but also alleviate the shortage of sand aggregate in construction industry.However,coal gangue concrete has some shortcomings in mechanical properties such as low bearing capacity and poor ductility.Therefore,this paper proposes that GFRP material with strong corrosion resistance and good ductility is prepared into pipe and used as template to cast coal gangue concrete to form a new combined structure form of GFRP constrained coal gangue aggregate concrete.For a better understanding of the mechanical properties of the coal gangue concrete GFRP constraint,this paper studies on the mechanical properties of the structure of the new type composite short column axial compression tests have been carried out,the study of the influence factors of its mechanical performance analysis,and the known experts and scholars put forward the FRP material ultimate bearing capacity and ultimate strain of confined concrete,on the basis of theoretical model,The modified calculation formula considering coal gangue replacement rate and thickness of GFRP tube in core concrete is put forward,which provides theoretical reference for further research on GFRP constrained coal gangue concrete.Firstly,20 composite short columns were designed and prepared,and the axial compression tests were carried out on them.In this test,the influence of the above factors on the failure process and morphology,bearing capacity and ductility of composite columns under axial compression conditions were mainly considered,including the content of coal gangue in concrete coarse aggregate,thickness of GFRP tube and expansion agent.The structure shows that the failure of GFRP confined coal gangue concrete column is different from that of traditional steel tube confined concrete,and the collapse of GFRP tube fiber is the failure symbol.The restraint of GFRP pipe on coal gangue concrete can greatly improve the bearing capacity and ductility of coal gangue concrete.Among the influencing factors,the thickness of GFRP tube has the most obvious effect on the mechanical properties of the composite column,followed by the content of coal gangue and expansion agent.The composite column with the largest thickness of GFRP tube,0% coal gangue replacement rate in concrete and adding expansion agent has the best mechanical properties.After using all materials in this experiment the basic mechanics data,on the four classic model of ultimate bearing capacity and ultimate strain of confined concrete is calculated,and the calculated model predicted values and the experiment validated the data analysis,and choose a better prediction results respectively limit bearing capacity model and ultimate strain model,The regression analysis of the above two model formulae was carried out by using the experimental data,and the prediction results of the model formulae were modified by using the new parameters.The comparison between the modified prediction results and the experimental results shows that the predicted values obtained by the modified model formula are in good agreement with the experimental results.Finite element model was built with the finite element software ABAQUS,the combination of coal gangue replace rate of the specimens and the thickness of GFRP tube two parameters are analyzed,through the analysis found that for the composite specimen,tube thickness increase the positive impact on the bearing capacity of composite specimens,and the increase of coal gangue adverse influence on the mechanical properties of the composite specimens exists,This result is consistent with the experimental conclusion in this paper.A more accurate finite element model is obtained through adjustment,which provides a theoretical basis for the further study of GFRP constrained coal gangue concrete composite members.There are 37 figures,17 tables and 59 references in this paper. |
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