| Nowadays,with the rapid development of the construction industry,the demand for concrete is large,and a lot of natural resources are needed,which will destroy the surface vegetation and cause environmental problems.The recycling of waste concrete fits the requirements of sustainable development in China.At the same time,with the occurrence of accidents such as’ ship collision bridge ’,’ explosion shock ’ and ’ terrorist attack ’,the probability of impact and explosion load on engineering structures is increasing.Therefore,it is essential to study the recycled concrete specimens dynamic response under the impact load.In this paper,a large-scale split Hopkinson bar(SHPB)is used.Through the research method of experiment and numerical simulation,dynamic impact compression tests under different impact pressures were carried out on recycled concrete with different replacement rates,and we used finite element analysis software to simulate and analyze the experimental procedure.The results obtained in this paper provide a theoretical basis and experimental basis for the application of recycled concrete as an impact-resistant structure in engineering,and have certain guiding significance for the application and promotion of recycled concrete.The following are the primary research topics and conclusions covered in this essay:(1)The recycled concrete under five different replacement rates of 0 %,25 %,50 %,75 % and100 %,standard cube compression tests were performed.However,the static pressure strength measured by recycled concrete RAC is lower than that of regular concrete NC0,and the replacement rate has an inverse relationship with the static pressure strength of recycled concrete.(2)Under three distinct impact pressures of 0.20 MPa,0.22 MPa,and 0.24 MPa,large-scale dynamic impact experiments were conducted on regular concrete and recycled concrete.According to the experimental findings,these two types of concrete’s final failure mechanisms can be classified into three categories: "slight cracking" "cracking" and "crushing",and the peak stress and peak strain of the two kinds of concrete are proportional to the impact pressure and inversely proportional to the replacement rate.Comparing the strain rate sensitivity of the two kinds of concrete,it is found that ordinary concrete has higher strain rate sensitivity.(3)ANSYS / LS-DYNA numerical simulation software was used to simulate the dynamic impact process of recycled concrete.The numerical simulation findings’ pulse waveform curves were contrasted with the outcomes of the experiments.The pulse waveform’s general tendency was consistent,and there was little difference between the transmitted and reflected waves’ peaks.Similar to the experimental results,the reliability of the model was verified.(4)The fracture morphology of concrete and the maximum principal strain cloud obtained in the numerical simulation were analyzed.The results showed that with the increase of impact pressure,the fracture state of the specimen is aggravated,and the crack and fracture of the specimen are generated.At the same time,the waveform curve and stress-strain curve of recycled concrete at higher strain rate were predicted. |
