The Dynamic Mechanical Behaviors Of Desert And Concrete After Elevated Temperature And Constitutive Model

At present,the concrete construction is a wide use of construction form all over the world.Since the concrete building is usually subjected to impact loading during normal usage,the construction generates damage and severe failure.Therefore,it’s vital to study the property feature of concrete subjected to impact loading.Meanwhile,in the recent years,the requirement of construction sand gradually increases with the increase of building quantity and there is a serious shortage for sand resource.There is an abundant desert sand resource in western China.If the desert sand can be used to replace building sand and desert sand concrete can greatly apply to the requirements of engineering,the environment can be effectively protect and the building cost will decrease.Besides,the building accident on fire gradually increases in recent years and it usually threatens the safety of life and property In this study,the relation between strain rate,temperature,desert sand replacement ratio and the mechanical propertied of desert sand concrete after high temperature is analyzed by the combination of experimental research and theoretical analysis.The main research content is shown as follows:1)The dynamic compressive strength of desert sand concrete after high temperature is studied.The effect of strain rate,temperature and desert sand replacement ratio on the dynamic compressive strength of desert sand concrete after high temperature is analysed.The experimental result is indicated as follows:The dynamic compressive strength of desert sand concrete after high temperature gradually decreases with increasing temperature.With increasing desert sand replacement ratio,the dynamic compressive strength of desert sand concrete after high temperature increases firstly and then decreases.The dynamic compressive strength reachs optimal value when the desert sand replacement ratio is 40%.Moreover,with increasing strain rate,the dynamic compressive strength of desert sand concrete after high temperature and DIF increases,which shows the rate effect of desert sand concrete after high temperature.2)According to the dynamic flexural strength of desert sand concrete after high temperature,the influence of strain rate,temperature and desert sand replacement ratio on the dynamic flexural strength and deflection is studied under the different fly ash content(10%and 20%).Meanwhile,the damage model of dynamic flexural strength of desert sand concrete after high temperature is established.The experimental result is indicated as follows:Under the different fly ash content,the appearance feature of desert sand concrete after high temperature is similar.With increasing temperature,the flexural strength of desert sand concrete after high temperature gradually decreases.The flexural strength and deflection of desert sand concrete after high temperature increase with increasing strain rate.With increasing desert sand replacement ratio,the flexural strength of desert sand concrete after high temperature increases firstly and then decreases.The flexural strength arrives the maximum value when desert sand replacement ratio reachs 40%.3)In order to exactly calculate the dynamic constitutive relationship of desert sand concrete after high temperature,based on the nonlinear viscoelastic constitutive model(ZWT model),stress-atrain curves of desert sand concrete after high temperature subjected to dynamic loading are fitted and the dynamic constitutive relation of desert sand concrete after high temperature is established.There are a great similarity between results of compressive experiment and predicted model,so the constitutive model established can greatly predict the dynamic constitutive behavior of desert sand concrete after high temperature.