| The strength of concrete under dynamic load is improved to a certain extent compared with the strength under static load.According to the existing experimental data at home and abroad,China's latest "Code for Seismic Design of Hydraulic Structures(GB51247-2018)" stipulates: "Concrete dynamics The standard value of strength can be increased by 20% compared to its static standard value".Tests show that viscosity is an important factor affecting the mechanical properties of dynamic load concrete,but the mechanism of viscosity is not clear at present.At the same time,in concrete material test and structural dynamic design,inertia and damping will have an impact on the results,so directly It is not reasonable to use the material strength test results in the dynamic test as the structural power design parameters.In this paper,considering the inertia of concrete,the influence of viscosity on the dynamic strength of concrete is analyzed.The mechanism of concrete strength enhancement under dynamic load is discussed.Study the effect of damping on the dynamic strength of concrete and the effect between viscosity and damping.The value of dynamic parameters in concrete structure design is discussed.The specific results are as follows:(1)The paper carried out dynamic compression test and tensile test of concrete after immersion in liquids with different viscosities at different loading rates.The relationship between strength,deformation characteristics,immersion liquid viscosity and loading rate of concrete under compression and tension is analyzed.And the multi-regression method was used to analyze the mechanism of viscosity affecting concrete strength under dynamic load.(2)The paper uses different pad and free suspension method to measure the vibration attenuation of concrete after immersion in liquids with different viscosities.Draw the damping envelope of different viscous concrete.Calculated the damping value of concrete under different test methods.The relationship between liquid viscosity and structural damping in concrete was studied.(3)The dynamic compression test of concrete was simulated by numerical simulation method.The dynamic failure law of concrete structure considering the influence of inertia and viscosity was studied.The influence of inertia and damping on the concrete strength under dynamic load was analyzed.(4)By analyzing the relationship between inertia,viscosity and damping under concrete dynamic load,the influences of different factors in structural dynamic analysis and material dynamic test are studied,and the values of parameters in concrete structure dynamic design are discussed. |
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