| CFST column structure has excellent mechanical properties and is widely used in construction.In actual engineering,during the service life of the building,the CFST is often in an eccentric stress state,and the long-term load will aggravate the deformation of the component.Therefore,it is of engineering significance to study the effect of the long-term load on the eccentric mechanical properties of the CFST member;at the same time,with environmental problems.The aggravation of the aggravation,many provinces and cities in my country have become acid rain-prone areas,and acid rain has a corrosive effect on the outer steel of CFST,weakening the physical properties of the steel pipe,reducing the bearing capacity of the components,and the impact on the components cannot be ignored.In this paper,the eccentric mechanical properties of CFST columns are studied for long-term load and acid rain corrosion.In this paper,the effects of creep and corrosion on the mechanical properties of CFST members are studied and discussed by combining experiments and numerical simulations.The test includes the eccentric pressure creep experiment of concrete filled steel tube,the electrical corrosion experiment of concrete filled steel tube,and the eccentric pressure failure experiment of concrete filled steel tube.After sorting out the experimental results,combined with numerical simulation,the specific research and analysis process is as follows:(1).The effect of long-term eccentric load on the deformation of CFST was studied.The experiment applied long-term eccentric load to 12 concrete-filled steel tubes,and 1 member was subjected to long-term axial load as a comparative specimen.The experimental results showed that the deflection and strain of the member increased with the load holding time.and increase,and the deformation of the component is faster in the early stage of loading,and gradually becomes stable in the later stage.(2).The influence of acid rain solution on the corrosion of steel is studied,and energized corrosion of components is divided into three methods: partial corrosion,total corrosion,and no corrosion.Combined with the difference of corrosion time,Faraday’s law of electrolysis is verified by measuring the corrosion depth.Experimental results: The measured corrosion thickness of steel tubes is in good agreement with the calculated results of the electrolysis law,and it has certain accuracy to predict the corrosion rate of concrete-filled steel tubes.(3).The eccentric pressure failure of the CFST members after creep and corrosion is carried out,combined with the load-displacement curve load,the load-strain curve,the deflection,and the damage,the effects of long-term load and corrosion on the mechanical properties of the CFST are analyzed.It is found by comparison that long-term load and corrosion will reduce the initial stiffness of the component and increase the deflection and strain when the component reaches the ultimate bearing capacity;further comparison shows that compared with the long-term load and local corrosion,total corrosion has a greater impact on the component.(4).The long-term load will increase the initial deflection of the CFST long column,and the corrosion effect will reduce the restraint of the steel tube on the core concrete,both of which will reduce the eccentric bearing capacity of the components.Calculate the bearing capacity of each batch of CFST creep and corrosion.The reduction factor is found to be correlated with the long-term load holding time and the corrosion rate.(5).The finite element calculation model of ABAQUS was established,and compared with the experimental results,it was verified that the model has certain accuracy.Further parameter analysis was carried out,and the simplified calculation formula of the eccentric bearing capacity of concrete filled steel tubes was fitted,and compared with the ultimate bearing capacity of the most total eccentric failure,it was found that the calculation results were consistent with the experimental results. |
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