Experimental Study On SHPB Impact Behaviors Of Plain Concrete At Elevated Temperatures

In recent years, fire frequently happened in buildings which always leads to collapse and gas explosion causing high temperature and dynamic impact loading on structure at the same time. Besides, terrorist attacks, such as car bombers or explosions of chemical factories may cause the same influence on structure, leading to local failure, even overall collapse. Concrete impact experiments under high temperature have been done using a special high-temperature test equipment and split Hopkinson pressure bar(SHPB) equipment in this thesis. The main works come as follows:(1) The high temperature SHPB impact test method was investigated. Combined with experimental tests and numerical simulation, the heating system was determined.(2) Static mechanical properties of concrete at elevated temperature were tested. Stress-strain curves of concrete were abtained, the influence of temperature, water-cement ratio and aggregate on compressive strength and elastic modulus of oncrete were investigated.(3) Microstructure of concrete at elevated temperature was obtained by high resolution scanning electron microscopy. The influence of temperature, water-cement ratio and aggregate on microstructure of concrete were investigated. Combined with the results of previous studies, the microscopic mechanism of temperature effect on mechanical properties of concrete was probed.(4) The dynamic mechanical properties of concrete under impact loading were tested at elevated temperature.Stress-time curves,strain-time curves and stress-strain curves were obtained. The influence of temperature, water-cement ratio and aggregate on ultimate dynamic strength and deformation of oncrete were investigated. The function of dynamic increase factor(DIF) of concrete due to temperature and strain rate was proposed.