D_iem Model For Damage Assessment Of RC Frame Structures Under 3D Ground Motion

A scientific quantitative assessment of the damage of a building structure is one of the most important technical aspects of structural collapse resistance research and structural resilience analysis.However,there are limitations in the existing damage models and modal indicators for the quantitative assessment of damage to reinforced concrete frame structures under three-dimensional ground shaking.model and integral floor damage model are given on this basis,and thus a systematic D_iem（Damage Indies of Integration of Element Materials）damage assessment model for RC frame structures from material-section-component-floor is established,with the following work:（1）Taking an RC frame structure that was severely damaged in the Ludian earthquake as the Benchmark model,the seismic damage of the main components and the overall structure was systematically evaluated based on the seismic damage phenomenon,and the finite element model was established and verified by using Open Sees.The reliability provides a reasonable research object for the follow-up calculation and analysis of D_iem damage model.（2）Four weighted combination methods suitable for the D_iem model are proposed to calculate the damage index of a single frame column based on the plastic hinge section damage at both ends of the column.Taking the typical frame column of the Benchmark model as the research object,comparing the results of frame column damage calculations based on four weighting methods obtained from multiple three-dimensional ground motion records.the damage weighting method is optimized,and the damage index of the second-order effect of gravity is considered reasonably,and the D_iem damage model of a single RC frame column is established.（3）Propose four weighted calculation methods of damage index from frame column to whole floor that are suitable for D_iem model.Taking the bottom layer of Benchmark model as the research object,conduct IDA analysis on multiple three-dimensional seismic motion records of the structure,and compare the four Based on the calculation results of the floor damage index.Then the method of joint weighting of damage and gravity load is selected,and the D_iem damage model of the floor of the RC frame structure is established based on the damage index of the frame column.（4）Seismic damage classification standards based on damage phenomena respectively give suggestions for the division intervals of seismic damage of RC frame columns and RC structure floors based on D_iem damage index.Using the direction characteristics of the D_iemmodel,draw a quantitative analysis of frame columns or overall floors The"damage ring"with the difference in damage degree in different directions is convenient for judging the collapse tendency of the frame column and the overall structure.Using the D_iem model to quantitatively measure the characteristics of the influence of axial force fluctuations on the structure and component damage,a comparative analysis of the effects of vertical seismic action on damage to structural floors.The results show that the vertical earthquake action may have a significant impact on the damage degree of the structural floor.According to the different earthquake actions,the damage of the structural floor may be reduced or aggravated.The D_iem damage model of the RC frame structure floor proposed in this paper can not only quantitatively evaluate the damage of the structural floor and components in any direction at a certain time under any three-dimensional loading history（including horizontal two-way earthquake action and vertical earthquake action）,but also quantitatively analyze its The damage situation at any time in a certain direction is applicable to the damage assessment of RC frame structures under actual three-dimensional earthquake motion,and can provide high-precision evaluation indicators for the collapse resistance analysis and seismic toughness analysis of structures.