| Hollow reinforced concrete column with inner steel tube(ISTHRC column)is a new type of column in which the steel tube is added to the inner wall of the hollow reinforced concrete column.In contrast,the ISTHRC column prevents damage that begins with the concrete lining and simplifies construction by using steel tubes as internal formwork.In this paper,three kinds of ISTHRC specimens are studied,namely,IOSTHRC specimens lined with octagon steel tube,IRSTHRC specimens lined with square steel tube and ICSTHRC specimens lined with circular steel tube.IOSTHRC is the experimental specimens in this paper,which is also the main object of this article.In this paper,the following contents are mainly studied by experiments and ABAQUS simulation:(1)Drop hammer impact test was carried out on IOSTHRC specimen.The experimental variables include impact height,bearing condition and axial pressure ratio.Based on the test results,the data of failure form,impact time history curve and displacement time history curve are analyzed and discussed in this paper,and the influence law of various variables on these results is preliminarily studied.A hollow reinforced concrete specimen in the same batch of experiments is compared with this kind of specimen in the same working condition.The comparison results show that replacing the built-in steel cage with the inner steel tube can greatly reduce the residual deflection of the column and significantly improve the impact resistance.(2)Considering the strain rate effect of material,The finite element model of IOSTHRC specimen was established by ABAQUS finite element analysis.The model is introduced in detail from the aspects of material constitutive,component parameters,constraint contact,load application and element type.The rationality of the model is verified by comparing the failure modes,impact force and deflection of the simulation and experiment.Through comparison and verification,the established model is in good agreement with the experiment on the whole,and the optimal condition of agreement is found as the basic condition for further parameter analysis.For some differences between the model and the experiment,the possible reasons are summarized.(3)On the basis of the established finite element model,the fixed support impacting 5m and simply supported impacting 5m was used as the basic working conditions.I studied the influence of some factors on the dynamic response of the specimens under impact load.IRSTHRC and ICSTHRC specimens were introduced to ensure the equivalence of the amount of various materials.The dynamic response characteristics of the three ISTHRC specimens were compared by comparing their deflection time history curves.The IRSTHRC specimen has the best crash-resistance in the study area of this article if the deflection of the specimen is used as the crash-resistance index. |
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