The Research On Damping And Seismic Damage Model Of RC Element

Damping is one of the basic dynamic properties of structure in vibration, which has considerable effects on structural dynamic response. The physical mechanism of damping is complex, so damping can not be measured directly like mass and stiffness. The estimate of damping has always been a problem needs to be solved in earthquake resistant design. In vibration, all responses of buildings are the functions of damping, so the estimate of damping value affects on the reliability of the dynamic analysis results. A small change in damping may cause a large change of the structural response and even more. With the improvement of the requirement on the disaster resistant capacity of building and the application of some kinds of technologies, such as disaster mitigation, earthquake isolation and earthquake mitigation, it will affect the application effect of those technology, whether the value of inherent damping of the structure is reasonable or not. Consequently the research on the physical mechanism and reasonable value of damping become the exigent and intractable subject today. Due to complexity of damping physical mechanisms, understandings on damping phenomenon are limited. So it is necessary to study the damping of material and member. The ability of damping energy dissipation is related to the damage degree of structure and members, but existing damage criteria does not consider that.The main research contents of this paper include:1. The concept and significance of research on damping is presented. There are the reviews of the history and actuality of damping research. The mechanism and classification of damping energy dissipation are analyzed in this paper. And some familiar damping models and the according evaluation methods of these damping models are also presented in this paper.2. A damping dissipation coefficient of material J is defined. Choose a flexural beam as study object and make an analysis of damping dissipation of bending beam. Damping energy dissipation is considered as three-dimensional energy dissipation. The damping ratio of the beam is related to the damping property of the material, the section of the beam and the type of load. Cross-section factors of the there familiar section shapes and longitudinal stress distribution factors of rectangular bending beams under three kinds of loads are presented and discussed. At last, the damping dissipation coefficient J for reinforced concrete materials with different concrete strength, different elastic modulus and different reinforced ratios based on test data in existence. The relationships between J and the three variables are analyzed in this paper.3. The damage problems in damage based structure FEM modeling are studies in this paper. Damping damage is proposed to formulize the damping variation when damage occurs. The accompanying damping damage and the original damping damage are defined. A damping damage modeling method considering accompanying damping damage and material damping damage simultaneously is proposed. Several damage modeling methods are investigated to evaluate its performance in damping damage modeling. Comparison of these methods is given by numerical studies. Moreover, the effect of local stiffness damages upon the local damping properties, vibration energy distribution, and the behaviors of damp dissipation of structures are investigated separately. It is suggested that the stiffness damage and damping damage should be considered simultaneously in structural damage modeling, and the suitable damage modeling methods should be chosen.4. The distribution and characteristic of the damping in reinforced concrete structures are studied in this paper. Some current seismic damage models are then presented .Based on the analysis of these models, a new modified seismic damage model for reinforced concrete beam column considering the influence of damping energy-dissipation is presented.