Damage Characterization Study Of Reinforced Concrete Frame Structures Based On Energy Dissipation And Damage

Reinforced concrete frame structures are widely used in China in recent years because of their flexible layout,low cost and durability.However,according to the investigation and analysis of earthquake damage,it is shown that even if the frame structure is designed strictly in accordance with the seismic code,after the structure enters the elastic-plastic state under strong earthquake,the frame structure may collapse to varying degrees only with a single deformation index for seismic design.In view of the above problems,This paper summarizes the current research progress of damage theory of reinforced concrete structures based on material level,component level and structure level,and points out that there are disjointed problems: the combination form from material damage to component damage;the combination of component damage to overall damage.Aiming at the failure evolution process of reinforced concrete frame structures under large earthquakes and the evaluation method of seismic damage,the degradation law of the overall performance of structures under strong earthquakes is analyzed,and the overall damage model reflecting both "displacement first overtaking damage" and "cumulative damage damage damage damage damage damage damage damage damage" is established.The quantitative description of the overall damage degree in the collapse process of RC frame structures is realized,and the RC frame structure is evaluated.Seismic reliability of structures.The results show that:1.In the initial stage of simulated loading,the damage of reinforced concrete frame structure is mainly caused by the elastic-plastic deformation caused by the "first overshoot of displacement",while the "cumulative damage of energy dissipation" has a relatively small impact on the structural damage.With the increase of the horizontal displacement of the vertex and the number of loading cycles,the proportion of damage caused by the "cumulative energy dissipation" increases and the cumulative energy dissipation pairs up.The contribution of structural damage increases gradually.2.The damage model based on the energy dissipation principle established in this paper can better reflect the actual damage evolution law of reinforced concrete frame.The damage index is 0 at the initial stage of structural damage,which overcomes the defect that some other damage indexes are not 0 at the linear elastic stage when the structure does not produce damage.Moreover,because the energy dissipation is irreversible,the index also conforms to the monotony of damage index.Moreover,the upper and lower bounds of the damage model converge,that is,when the whole structure collapses,the damage index D = 1,and the model is simple to calculate,versatile,less constrained by parameters,so it can be more convenient to assess structural damage.3.Under the action of frequent earthquakes or rare earthquakes,the overall damage of reinforced concrete frame structure is very small in the early stage of loading,and the structure is in the stage of "elastic work",and the performance of reinforced concrete frame basically does not deteriorate.In the middle stage of loading,the overall damage of structure is mainly caused by "displacement first-over-failure";when the structure enters the stage of "elastic-plastic work",the structure will be damaged.The overall damage of the structure is mainly caused by "cumulative damage of energy dissipation",and in the elastic-plastic stage,the overall damage of the structure tends to be stable gradually,so the seismic performance of the structure decreases slowly.