Researchers Investigate Experimental Behavior of the Seismic FAMD

Sunday, November 26, 2017 - 16:46

Researchers of International Institute of Earthquake Engineering and Seismology have reached to the formulation to strengthen structures against earthquakes through studying dampers extensively.

According to an ISCA report, In recent years, in conjunction with developments of supplemental passive energy absorption devices , the idea of buckling of thin-walled tube and the use of this property as an accordion metallic damper (AMD) as a valid seismic energy absorption damper was entertained throughout the scientific world.

Extremely good behavior for seismic damping has been resulted and shown for the AMD's. For the purpose of improvements on AMD's, filled accordion metallic dampers (FAMD) are introduced and analytically and experimentally investigated.

First analytical studies have lunched on FAMD's for identification of their behavior under axial cyclic loads. After specifying the preliminary material properties, a series of AMD's and FAMD's filled by polymeric foam were subjected to dynamic tension and compression.

Based on the results obtained, using the appropriate filling inside the AMD's is a suitable technique for the purpose of improvement some of important specification such as the number of cycle before failure, amount of dissipated energy, plastic tension and pressure capacity and the effect of interaction between foam and accordion thin walled tubes plays a major role for this purpose specially in low capacity AMD's.

Results show that Based on experimental results, using polyurethane foam as filler inside Accordion Metallic Dampers help to control buckling mode of dampers under axial cyclic loading and prevent contact of corrugates (concentration of deformation between corrugates), consequently will increase number of cycle before failure of damper. This effect is more significant for high capacity dampers (wall thickness=2 mm)

Interaction effects between foam and thin-walled accordion tubes play a major rule for improvement some of damper characteristics such as amount of dissipated energy, compression and tension capacity. This effect is more significant for low capacity dampers (wall thickness=0.6 mm)

Effects of foam filling of damper, although increase amount of dissipated energy but because of sharp increasing of compression and tension capacity, hysteretic equivalent damping decrease in low capacity specimen.

Amount of dissipated energy, compression and tension capacity of filled damper by polyurethane foam are more than algebraic sum amount of dissipated energy, compression and tension capacity of foam and AMD separately.

The research has been carried out by Fariborz Nateghi-E, faculty member of International Institute of Earthquake Engineering and Seismology, Mehrtash Motamedi, Editor-in-Chief in University of British Columbia, Canada and E Izadi-Z, professor of Najafabad IAU.

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