The Effect Of Dynamic Behaviour Of Concrete By Loading History

Large-scale concrete structures inevitably are affected by dynamic loads during thecourse of using it, such as dams are affected by seismic load, offshore production platformis affected by wave load, high-rise buildings are affected by seismic and wind load and soon. Although structures will not be affected by these loads all the time, these loadings areimportant control factors on controlling structure design because they are unpredictableand short-term significant destructive to structures.The dynamic performance of concrete have been more deeply understood in previousstudies, but most of studies were in the initial static load conditions, actually concretestructures are firstly endured a certain static load and then endured some dynamic loads. Atthe some time, China is a country of more than one earthquake, and west of China is themajor earthquake area which has very high seismic intensity and frequency. Earthquakeaffair is the controlling condition in design and also is key technical problems forestablishing the engineering projects in high ach dams of western China. Accurate analysisof_concrete structure under complex stress path, comprehensive consideration the dynamicand static loads, then comprehensive understanding dynamic performance of_concrete is animportant task. This paper specific reasearches are as follows:（1） To study the dynamic uniaxial compression test of concrete under monotonicloading history of0,0.4f_c,0.6f_c,0.75f_c,0.85f_c（f_c is the highest uniaxial compressivestrength） and strain rate of10^-5,10^-4,10^-3/s, comparatively analysis the mechanicalproperties such as （peak stress, peak strain, elastic modulus） of concrete under differentmonotonic loadings history and strain rate.（2） To study the dynamic uniaxial compression test of concrete under two cyclicamplitudes （0.1f_c,0.2f_c）, two cyclic frequencies （0.5Hz,2.0Hz） and strain rate of10^-5,10^-4,10^-3/s, comparatively analysis the mechanical properties such as （peak stress, peakstrain, elastic modulus） of concrete under different cyclic amplitude, cyclic frequency andstrain rate.（3） Selecting appropriate damage constitutive model of uniaxial compression ofconcrete, fitting the stress-strain under different strain rate of_concretes which experiencingmonotonic loading history and cyclic loading history. Calculating and comparing thedamage variable value of concrete which experiencing monotonic loading history andcyclic loading history.（4） Analysis the curve of characteristic points between damage variable and strain, defining the sill value of damage strain after concrete experienced loading history, at thesame time comparatively analyze the sill value of damage strain under different loadinghistory and strain rate.