Novel Devices For Seismic Resistance And Resilience Of Structures

The current design uses the response modification factor to consider the ductility and energy dissipation to improve seismic resistance capability of structures.However,this method normally causes plastic damage in structural components,which leads to dismantlement of structures after the earthquake.A classical case is Northridge Earthquake,which happened in 1994 in America with a 6.6 Richter scale.Although the casualties were 57,the economic loss were approximately 50 billion dollars.After that,the resilience of building structures became a heated issue among designers and researchers.To improve resilience,achieving damage control and self-centering feature are crucial.In this dissertation,a new damper,which could achieve damage control by limiting damages in replaceable energy absorbing steel plates(EASP)clusters,and a new self-centering damper are developed.The dissertation also compares the seismic responses of a concentrically braced frames equipped with buckling restrained braces(BRBF)with a one equipped with self-centering braces(SFBF).The novel damper developed in this dissertation dissipates earthquake energy by plastic bends of rectangular steel plates which are assembled in some replaceable clusters.The dissertation firstly gives formulas of mechanical properties based on elastic theory.Then,three full-scaled specimens were designed and tested complying with cyclic protocol.The dissertation also analyzes the results obtained from the test like hysteretic curves,backbone curves and strain time history curves to reveal capability of the damper and the influence of thick of the plates on the damper.Besides,a backbone prediction model is developed in Matlab.The accuracy of the model is verified by comparison with the results of the test.The model is also used to evaluate the influence of material constitutive.Finally,a design procedure is given to provide guidance for designers.The self-centering damper developed in the dissertation achieves self-centering feature by introducing pre-stressed system.By assembling energy dissipation elements and self-centering elements in parallel,the damper could achieve both energy dissipation and self-centering feature.The author gives the formulas of mechanical properties of the damper.Then,four full-scaled self-centering specimens and one specimen without self-centering feature were designed and tested confirming to cyclic protocol.The self-centering feature and energy dissipation capability of the damper are analyzed in the dissertation.Finally,the author builds two models for a concentrically braced frames equipped with buckling restrained braces(BRBs)and one equipped with self-centering braces(SCBs)in Opensees.The seismic responses(the maximum transient inter-story drift ratio,the distribution of inter-story drift,the maximum residual inter-story drift ratio,and peak floor acceleration)of these two models under 60 earthquake records with three intensities(FOE,DBE and MCE)are compared.The results obtained from the nonlinear responses history analysis are generalized by probability analysis.The results reflect the contribution of BRBs and SCBs on the seismic resistance capability of structures.