EQUIVALENT SHEAR SPRING MODELING METHOD OF SUPER TALL STEEL STRUCTURE BUILDING WITH CONTINUOUS ARRANGEMENT OF VISCOUS DAMPERS AND HYSTERETIC DAMPERS

Abstract

 Seismic control has become generally used in super tall steel structure buildings. A combination of viscous dampers and hysteretic dampers is increasingly used nowadays to ensure high earthquake resistance of high-rise buildings – as such, this is called a “combination-system”. In design of buildings, simple model such as equivalent shear spring model is frequently used. However, there is no current research on simple model of “combination-system”, thus, this paper proposes a method to create an equivalent shear-spring model of “combination-system” consisting of its characteristic values, dampers and their support members, and frames.

 In creating the shear spring model, the parameters are calculated by conducting static analysis of the building frame in four states – (i) state N for frame only state, (ii) state R in which an elastic spring with extremely high rigidity is placed in the damper’s installation position, (iii) state pN in which elastic springs are only placed in the hysteretic dampers’ installation stories, and (iv) state pR in which an elastic spring with extremely high rigidity is only placed in the hysteretic damper’s installation position.

 The parameters obtained from states pN and pR are important in evaluating seismic control effect of “combination-system”. The obtained characteristic values from state pN show that the upper limit of the effective deformation ratio in the viscous damper’s installation floor decreases. The obtained characteristic values from state pR show phase difference between the hysteretic damper load and viscous damper load.

 A 30-storey high-rise building with brace-type continuous arrangement of viscous dampers and hysteretic dampers is used to verify the proposed model. A total of 13 damper placement combinations are used in this study. This paper shows that the proposed model reproduces the results of time-history analysis of member models. With respect to energy absorption of damper, the proposed model is more accurate than the previous models because the former evaluates various characteristic values and can reproduce the damper load at each step of the time-history analysis.