Simulation research on story damping ratio modification based on a multistory frame structure
Determining an additional effective damping ratio is key to designing energy dissipation structures.To explore the influence of the number of floors with dampers on the safety of struc-ture design,this study used a multistory reinforced concrete frame structure in Xinjiang as the research object.Nonlinear time-history analysis and mode decomposition response spectrum anal-ysis of the equivalent structure model were performed.Based on shear force calculation results for each floor,the story damping ratio modification factor was introduced to promote iterative cor-rection of additional effective damping ratio of equivalent structure model.The results show that the story damping ratio modification factor of the equivalent structure model first increases and then decreases with an increasing number of floors with dampers when using the time-history analysis under small earthquakes.Moreover,the reduction rate is the lowest when the number of floors with dampers is three-fifths of the total number of floors.However,an equivalent struc-ture model where no less than two-fifths of the floors have dampers can meet fortification require-ments when using the time-history analysis under intermediate earthquakes.Considering the com-prehensive cost,the viscous dampers do not need to cover all floors.