Patro and Sinha 2008
In this paper the optimal seismic performance of friction devices, in order to reduce the response behavior of frame buildings, were numerically investigated. The design of the friction based passive energy dissipation devices was based on numerical simulation with constant coefficient of friction. Due to the non-linear relationship between dry friction and sliding velocity the writers investigated the energy dissipation devices with stiction and Stribeck effects the in friction model. Moreover, the response of 4-story example frame building with friction devices were investigated and discussed in terms of various dimensionless performance and optimal seismic performance of friction devices.
System Concept
The structure for the mathematical formulation was considered as a two dimensional shear building. Two degrees of freedom were used for each floor, corresponding to the horizontal displacement for the story and the brace. Simple friction energy dissipation devices were connected to the centerline of the beam soffit. Beam weight and loading does not have any effect on the sliding surface. The sliding plate has slotted holes and is sandwiched between two clamping plates with pre-stressed connection bolts. The slotted holes facilitate the movement of the sliding plate over the frictional interface at a constant controllable pre-stress force. The placement of sliders in the vertical plane of the beam guarantees that only the pre-stress force controls the normal load on the sliding surface. The presence of two friction interfaces for each bolt doubles the friction resistance.
Numerical Study
In order to idealize the dynamic behavior of the structure, two lumped mass models were used; on for the free frame structure and another for the brace with device. From entire solution process, the equations of motion were split into two subsets; non-sliding phase and sliding phase.
In order to characterize the seismic efficiency of friction devices, six dimensionless performance indices have been considered; displacements, acceleration, base shear, strain energy, input energy, and dissipated energy. The various performance indices were evaluated for realistic friction model. Values close to zero indicate excellent performance of the friction devices in reducing the response while values close to 1 or higher indicate ineffectiveness of the friction devices. According the results, pre-stress force is the most important parameter for the design of the friction devices.
Reference
Patro, S. and Sinha, R. (2008). “Optimal Seismic Performance of Friction Energy-dissipating Devices,” Proceedings of the 14th World Conference on Earthquake Engineering 2008, Beijing, China, October 12-17.