Numerical Research On Mechanical Property Of Concrete Under Static-dynamic Loading

Bridges, buildings and other concrete material engineering structures usually areeffected by dynamic load during their services，dynamic loadings such as vehicle load,wind effect and earthquake are also the key load effects to be considered in their design. Itis important to note that these engineering structures usually are under certain amount ofstatic or quasi static stress (such as dead weight etc.) before they are loaded by relevantdynamic load. Apparently, to study on the deformation and failure characteristics ofconcrete under the coupling loading of initial static load and cyclic dynamic load is ofgreat significance for the safety and the design theory improvement of engineeringstructures.In order to study the failure characteristics and the evolutionary process ofdeformation and stress under the combination of load, the writer simulated destructionprocess of concrete-like model under initially static and later the cyclic dynamic load. Thispaper analyzed the influence of initial static load level, frequency of cyclic loading and theamplitude of cyclic loading respectively on the failure and mechanical characteristics.The result shows that irreversible deformation increases with the increase of cyclingtimes and with the initial static load during the cyclic loading, that is the cracks inside thesample are firstly densified and then extended, which lead to depredate sharply, untildestruction. It is a process of damage accumulation in the course of loading, the damageincreases with the increase of cycle times, and the damage caused by a circulation isseverer than the its previous one at the same strain point. Before the failure of the concretesample, the sine wave (strain curve) rises as the cycling times of loading increases, and itscrest points and trough points show an approximate linear increase, and thus a failure mode"X" type failure is obtained.