The Research On Damping And Damage Criteria Of RC Bending Element

Damping is one of the basic dynamic properties of structure in vibration ,it has considerable effects on structural dynamic response. Damping physical mechanisms is complex, therefore damping is unlike mass and others that are measured directly. In vibration, all response of buildings are the function of damping, so damping value affects on the reliability of the dynamic analysis results. With the application of seismic isolation and seismic decrease technology, the value of structural inherent damping has a impact on application effect of seismic isolation and seismic decrease technology. Consequently research of damping physical mechanisms and reasonable value become the exigent and intractable subject. Due to complexity of damping physical mechanisms, understandings of damping can but rest on facies of damping phenomenon. So the author think it is necessary that material and member damping is studied. damping energy dissipation relate to damage of structure and members, but existing damage criteria neglect to this. This main research contents of the thesis include: 1. The history and actuality of damping research is reviewed, damping energy dissipation is defined, and the sources and classification of structural damping energy dissipation is analysed. 2. By analysis of relative testing results ,the formula of periods and buildings height, story number are presented ,and compared with formula of Refs.26. The influences of foundation classifications, vibration forms, periods, buildings height ,story number and vibration modal on structural damping ratio are discussed, the relationship of damping and buildings height and story number have uncertainty, the formula of basic modal damping and others modal damping is presented. Revised Rayleigh damping modal is presented by comparing the advantage and disadvantage of current main damping modal, and the method of damping ratio in complex damping structure is discussed. 3. RC bending elements are researched where damping is regarded as spatial distributing energy dissipation. By research of relationships between damping dissipation and spatial distributing stress amplitude in vibration, the formula for damping energy dissipation and spatial distributing stress amplitude is presented, including concrete strength, ratio of stirrup strength and maximum shearing stress. Index of three section shape and longitudinal stress distribution of rectangular bending beam under three loads are presented and discussed. Finally, stress amplitude coefficient n and damping dissipation index J are obtained based on relative test results. 4. Based on relationship of damping dissipation energy and damage , the damage criteria including damping dissipation energy and ductile index is presented, and it is validated according as relative testing results. Finally according to this paper production, author bring forward several research fields that need more study.