Investigation Of Analysis And Control Of Residual Displacement In Reinforced Concrete Frame Structure

As illustrated by previous earthquake damage,although the structures with ductility design were allowed to dissipate energy through ductile defor mation,these damaged structures have to be strengthened or demolished due to the excessive residual displacement.The residual displacement of the structure has a direct relationship with the cost of strengthening after the earthquake.Therefore,the residual displacement has gradually aroused the attention of the researchers and become an important index for the performance-based seismic design and evaluation.It is of great theoretical significance and application value to carry out the research on the residual displacement.Currently,the research on residual displacement of structures under strong earthquakes was quite limited,especially in the overall structural level.In this dissertation,the residual displacement of single degree of freedom(SDOF)was analyzed systematically,and a damage evaluation method was proposed.Besides,the influence and the distribution of the multiple degree of freedom(MDOF)was further investigated.Finally,the methods of controlling the residual displacement were proposed.The main contents and results of this dissertation are as follows :(1)120 ground motions from four kinds of sites were selected for the SDOF system.Through the elastic-plastic dynamic time history analysis,the parameters such as site condition,post-yield stiffness ratio,strength reduction coefficient and period were analyzed to find out their effects on the residual displacement.The results showed that site condition,post-yield stiffness ratio and period were the main factors affecting the residual displacement,while the strength reduction coefficient had little effect on the residual displacement.In addition,the influences of stiffness,strength reduction factor,concrete cracking and bar-slip on the residual displacement were studied by the Klough model and Pinching model.(2)As shown by the correlation analysis,there was a good linear relationship among the residual displacement,the maximum displacement and the hysteretic energy.On the basis of Park-Ang damage model,a damage evaluation method based on the residual displacement was proposed for the SDOF system.In addition,a formula for calculating the residual displacement of the SDOF was proposed based on the influence factors.(3)Based on the analysis of 2,5 and 9 floor reinforced concerted(RC)frames,the distribution of the residual displacement along the height of the frames and the relationship between the residual displacement and maximum displacement were obtained.Based on the linear relationship among the residual displacement,the maximum displacement and the hysteretic energy,the damage evaluation formula for the RC frames was proposed by introducing the importance ratio of each layer.In addition,the limit of the residual displacement was proposed.(4)Due to the causes and influencing factors of the residual displacement,the variations of the residual displacement were studied by adding the buckling restrained brace(BRB),shape memory alloy(SMA)and viscous damper in the frame structures.It was found that the residual displacement was reduced to a certain extent by these three methods,and the effect of the viscous dampers was more obvious than the other two methods.