CONCEPTS OF DAMPERS FOR EARTHQUAKE PROTECTION OF EXISTING BUILDINGS AND FOR DISPLACEMENTS RESTRAINTS IN SEISMICALLY ISOLATED BUILDINGS

Tuned Mass Damper (TMD) is one of the methods, known as a passive vibroprotecting device. The attempt to find the optimal parameters of TMD in the form of an additional flexible upper tenth floor (AFUF) in a 9-story frame building is presented. The efficiency of a single mass damper tuned to the first mode of building vibration is not very high. Therefore, three dampers tuned to the first three vibrations modes of the building are considered much more effective. However, solution of TMD in the form of AFUF contains some deficiencies, which are described in the paper. Therefore, the author has suggested providing flexibility to the damper using laminated rubber-steel bearings. In such case the AFUF will turn into an additional isolated upper floor (AIUF). Results of the earthquake response analyses and of dynamic testing of the existing 9-story apartment frame building before and after erection of AIUF are given. Paper also presents a new concept of dynamic damper (DD) to restrict the displacements of seismically isolated buildings. Since the maximum displacement occurs at the level of isolators the proposed damper as a mass-spring subsystem attached either above or below the isolation interface. It is suggested to use the pavement around the building to create the damper in low-story structures. Other variant of damper is suggested for the large multistory buildings. In both cases the spring of the damper is represented by laminated rubber bearings, which work in one case under the tension and in another under the compression forces. First real application of DD in construction of,a seismically isolated residential house is described in the paper.