Research On The Friction Pendulum Bearing With Invariable Friction Coefficient Based On The Theory Of Solid Lubrication

Traditional structures usually sustained significant damage in earthquake.To meet the requirement of earthquake resilient structure,isolation system was widely used.Friction pendulum isolation system has been widely concerned for its simple mechanical behavior and great self-centering performance.This paper proposed a kind of friction pendulum bearing(FPB)with pressureindependent friction coefficient.Physical tests were carried out to investigate the lubrication effect of variable solid lubricant material and lubrication form.The failure modes of FPB were also summarized based on the tests.In this paper,a user-defined element to simulation behavior of FPB was developed in ABAQUS and was verified to be correct.Based on the research of components,a reinforced concrete frame equipped with FPB was designed.Time history analysis were conducted to investigate its performance.Some major work are stated as follow:1.Based on the theory of solid lubrication membrane,separated inlay lubrication form aimed at pressure-independent friction coefficient is proposed in this dissertation,whose performance was similar to that of metal composite membrane.The behavior of FPB with arbitrary sliding surface shape was determined theoretically.It showed that the shape of the curve of elastic resilience was the same as derivative of the shape of sliding surface.The shape of sliding surface could be designed on purpose to meet different requirement.2.Physical tests on 9 specimens were carried out to investigate the lubrication effect of variable solid lubricant material and lubrication form.The friction coefficient of specimen used separated PTFE bar inlay lubrication form stabilized at 4% in wide pressure range.That of the specimen used other lubrication form or lubrication material varied obviously with the change of pressure.It decreased 30% from low pressure to high pressure.Two failure models of FPB were observed in the test.One is the wear and tear of solid lubrication membrane.The other is the loss of stability in vertical deformation.3.A user-defined element to simulate the behavior of FPB was developed in finite element analysis software ABAQUS.Two kinds of FPB elements,with pressure-independent friction coefficient and pressure-dependent friction coefficient respectively,were developed.The correctness of the user-defined element was verifiey based on a simple model.A reinforced concrete frame equipped with FPB was designed.Time history analysis was conducted to investigate its seismic performance.The CFPB had significant effect in decreasing structure acceleration.The acceleration decreased 25% with the help of CFPB.Thus,if the assumption that the friction coefficient is constant is introduced in dynamic analysis,the actual friction behavior of FPB should conform to the assumption.