Seismic Analysis And Design Of Buildings Using Viscous Dampers

Owing to the clear principles, flexible installation, good effect, fluid viscous dampers (FVDs) as passive energy dissipation devices for seismic protection have been applied in many large projects, and some successful verification during the real earthquakes have been reported as well. However, most projects with FVDs have been desiged by repeated time-history analysis until the objective is achieved, which is time-consuming and affect the application of FVDs. Thus, it is valuable to study an appropriate design method.In this thesis, the nonlinear dynamic properties of FVDs and the related SDOF structure were first discussed. FVDs on system response can be investigated in terms of two independent, dimensionless parameters. A nonlinear dynamic program was developed for the response analysis of the sytem with FVD.Next, the response spectrum method of SDOF system with nonlinear VFD was introduced. The principals of the SDOF system with FVD is discussed, and the relationship of the parameters of passive energy system (i.e., damping coefficient, damping exponent, brace stiffness) with structure vibration response (i.e., displacement, shear force) was established, then the performance curve of SDOF system with nonlinear FVDs was developed by using interpolation. It is convenient for SDOF structural design with FVDs by using the performance curve. Then, time-history method was used to verify the accuracy of the proposed response spectrum method.The above method was extended to MDOF system. The design step for multi-stories buildings was proposed. Based on target displacement was proposed. An example calculation process and time-history validation was given. The response spectrum method of multi-degree-of-freedom systems avoid repeated time-history calculated and can offer different design schemes for designers to choose, so it has high application value.Based on the response spectrum method, energy dissipation systems with magnifying mechanisms were studied. This system amplified the axial displacement of FVDs with magnifying configuration, so the energy efficiency of dampers can be improved especially for the condition of small displacement levels. The toggle-brace-system and scissior-jack system were mainly discussesd, and they were compared with chevron brace configuration through dynamic time-history analysis by SAP2000. Finally, the advantages and disadvantages were given to the designers for reference.