A hybrid seismic control system for buildings structures is considered, which combines a class of... more A hybrid seismic control system for buildings structures is considered, which combines a class of passive nonlinear base isolator with an active control system. The active control forces are applied to the structural base with the objective of reducing its displacements. An adaptive control law is formulated to compute the control forces in order to assure a form of stable behaviour of the system under seismic excitation and in the presence of uncertainties in the characteristics of the building of the hybrid control system. The global behavoiur of the structure-base isolator system is such that the absolute base displacement is significantly reduced, the price paid being a slight increase of the response of the structure. &nbsp
Base insolation systems partially uncoupled a structure from the seismic ground motion by means o... more Base insolation systems partially uncoupled a structure from the seismic ground motion by means of specially designed, replaceable, devices inserted between the structure and its foundation. These devices are capable of absorbing part of the energy induced by earthquake [1-4] and drastically reduce the seismic action transmitted to the structure. A numerical simulation of their effect on the seismic response of structures requires algorithms capable of analyzing structures with both elastomeric (hysteric) bearing and sliding (frictional) bearings [5,6]. Different numerical schemes for solving the equations of motion have been proposed. The most often used numerical procedures are monolithic step-by-step integration schemes, that is, schemes that lead to algebraic systems of equations involving both the degrees of freedom corresponding to the structure and the foundation. On the other hand, there is the possibility of coupling these two sets of unknowns interactively, rather than by solving the full algebraic system. These iterative methods, when combined with the proper linearization of the nonlinear terms, yield block iterative schemes as those considered in this paper. Their capability for solving other problems, such as the dam-fluid interaction or the motion of thermally driven flows, is described in reference [7]. In this paper, the application of schemes of this type in computing the seismic response of building structures with base isolation is considered, being this a problem of two systems coupled across their boundary conditions. The corresponding equations of motion are first written and details concerning the possibilities of numerical computation of the seismic response are given. Different manners of formulating block iterative schemes are described in a generic form and are then applied to the studied case. Their effectiveness in then explored on the basis of a complete numerical example
The objectives of the seismic design of buildings can be achieved by applying techniques of conve... more The objectives of the seismic design of buildings can be achieved by applying techniques of conventional design that consider the that the ground motion is transmitted to the structure through its fixed base. As an alternative to this traditional design, base isolation systems were developed consisting of mechanisms that partially uncouple the structure of the foundation ground to reduce, in this way, the damages of the structure and of its content. Decoupling is carried out by placing support devices between the base of the structure and its foundation that increase the flexibility of the overall structure-base system and that produce, at the same time, an appropriate damping. Despite the large number of studies on different base isolation systems, there are few comparative analyzes between these systems. In this monograph, structures isolated with different systems are compared with structures with conventional design. To this end, criteria for evaluating the behavior of the different systems have been defined. In the numerical studies, models with linear behavior for the structure and nonlinear behavior of the base isolation system have been considered. The type of nonlinearity of the isolation is formulated by means of differential equations, capable of describing both hysteretic and frictional systems
In this monograph, we study a type of hybrid system that combines a base isolation system with an... more In this monograph, we study a type of hybrid system that combines a base isolation system with an active control system that applies forces on the base. The control forces are calculated by means of a control law that guarantees an adequate behavior, both of the structure and of the base, considering a wide class of non-linearities of the base isolator and uncertainties in the dynamic model and in the excitation. In order to simulate properly the proposed hybrid system, algorithms are used able to analyze the effect of the base isolation with non-linear behavior. At the same time, it is necessary to have a control law that generates the active control force, whose objective is examined from the point of view of the behavior of the system composed by the structure and the base isolation in purely passive conditions. The control law is formulated for the two subsystems coupled through their boundary conditions. The active control forces are applied upon one of the subsystems in order to guarantee a form of practical stability. In this case, the subsystem over which the control acts is the base and the other subsystem is the structure. In the monograph the equations that describe the two systems of seismic base isolation considered in this monograph are developed (one hysteretic and the other frictional), the use of the hybrid system is justified, the different components are described and a critical analysis of the different existing hybrid systems is performed. The law of adaptive control is developed, the hypotheses are stated and the stability of said law is analyzed. The developed strategy is applied to different buildings with base isolation systems and numerical simulation results of their seismic response are shown
Se desarrolla, primeramente, la teoria lineal de los sistemas de aislamiento de base. A continuac... more Se desarrolla, primeramente, la teoria lineal de los sistemas de aislamiento de base. A continuacion se describen los sistemas de aislamiento que se consideran en la monografia y su comportamiento no lineal y se formulan sus ecuaciones del movimiento. Una vez presentados los procedimientos de calculo se incluyen resultados que comparan el comportamiento de estructuras de base fija con el de las mismas estructuras, pero con diferentes sistemas de aislamiento de base.
Se consideran edificios con sistema de aislamiento histeretico y friccional, se desarrollan sus e... more Se consideran edificios con sistema de aislamiento histeretico y friccional, se desarrollan sus ecuaciones del movimiento y se describen procedimientos de calculo numerico de la respuesta del sistema aislado. A continuacion se estudia la posibilidad de desarrollo de sistemas de aislamiento de base activos (sistemas hibridos). Despues de describir una nueva estrategia de control activo que se propone, se incluye un estudio numerico de simulacion de la respuesta sismica de edificios con sistemas de control hibrido.
A hybrid seismic control system for buildings structures is considered, which combines a class of... more A hybrid seismic control system for buildings structures is considered, which combines a class of passive nonlinear base isolator with an active control system. The active control forces are applied to the structural base with the objective of reducing its displacements. An adaptive control law is formulated to compute the control forces in order to assure a form of stable behaviour of the system under seismic excitation and in the presence of uncertainties in the characteristics of the building of the hybrid control system. The global behavoiur of the structure-base isolator system is such that the absolute base displacement is significantly reduced, the price paid being a slight increase of the response of the structure. &nbsp
Base insolation systems partially uncoupled a structure from the seismic ground motion by means o... more Base insolation systems partially uncoupled a structure from the seismic ground motion by means of specially designed, replaceable, devices inserted between the structure and its foundation. These devices are capable of absorbing part of the energy induced by earthquake [1-4] and drastically reduce the seismic action transmitted to the structure. A numerical simulation of their effect on the seismic response of structures requires algorithms capable of analyzing structures with both elastomeric (hysteric) bearing and sliding (frictional) bearings [5,6]. Different numerical schemes for solving the equations of motion have been proposed. The most often used numerical procedures are monolithic step-by-step integration schemes, that is, schemes that lead to algebraic systems of equations involving both the degrees of freedom corresponding to the structure and the foundation. On the other hand, there is the possibility of coupling these two sets of unknowns interactively, rather than by solving the full algebraic system. These iterative methods, when combined with the proper linearization of the nonlinear terms, yield block iterative schemes as those considered in this paper. Their capability for solving other problems, such as the dam-fluid interaction or the motion of thermally driven flows, is described in reference [7]. In this paper, the application of schemes of this type in computing the seismic response of building structures with base isolation is considered, being this a problem of two systems coupled across their boundary conditions. The corresponding equations of motion are first written and details concerning the possibilities of numerical computation of the seismic response are given. Different manners of formulating block iterative schemes are described in a generic form and are then applied to the studied case. Their effectiveness in then explored on the basis of a complete numerical example
The objectives of the seismic design of buildings can be achieved by applying techniques of conve... more The objectives of the seismic design of buildings can be achieved by applying techniques of conventional design that consider the that the ground motion is transmitted to the structure through its fixed base. As an alternative to this traditional design, base isolation systems were developed consisting of mechanisms that partially uncouple the structure of the foundation ground to reduce, in this way, the damages of the structure and of its content. Decoupling is carried out by placing support devices between the base of the structure and its foundation that increase the flexibility of the overall structure-base system and that produce, at the same time, an appropriate damping. Despite the large number of studies on different base isolation systems, there are few comparative analyzes between these systems. In this monograph, structures isolated with different systems are compared with structures with conventional design. To this end, criteria for evaluating the behavior of the different systems have been defined. In the numerical studies, models with linear behavior for the structure and nonlinear behavior of the base isolation system have been considered. The type of nonlinearity of the isolation is formulated by means of differential equations, capable of describing both hysteretic and frictional systems
In this monograph, we study a type of hybrid system that combines a base isolation system with an... more In this monograph, we study a type of hybrid system that combines a base isolation system with an active control system that applies forces on the base. The control forces are calculated by means of a control law that guarantees an adequate behavior, both of the structure and of the base, considering a wide class of non-linearities of the base isolator and uncertainties in the dynamic model and in the excitation. In order to simulate properly the proposed hybrid system, algorithms are used able to analyze the effect of the base isolation with non-linear behavior. At the same time, it is necessary to have a control law that generates the active control force, whose objective is examined from the point of view of the behavior of the system composed by the structure and the base isolation in purely passive conditions. The control law is formulated for the two subsystems coupled through their boundary conditions. The active control forces are applied upon one of the subsystems in order to guarantee a form of practical stability. In this case, the subsystem over which the control acts is the base and the other subsystem is the structure. In the monograph the equations that describe the two systems of seismic base isolation considered in this monograph are developed (one hysteretic and the other frictional), the use of the hybrid system is justified, the different components are described and a critical analysis of the different existing hybrid systems is performed. The law of adaptive control is developed, the hypotheses are stated and the stability of said law is analyzed. The developed strategy is applied to different buildings with base isolation systems and numerical simulation results of their seismic response are shown
Se desarrolla, primeramente, la teoria lineal de los sistemas de aislamiento de base. A continuac... more Se desarrolla, primeramente, la teoria lineal de los sistemas de aislamiento de base. A continuacion se describen los sistemas de aislamiento que se consideran en la monografia y su comportamiento no lineal y se formulan sus ecuaciones del movimiento. Una vez presentados los procedimientos de calculo se incluyen resultados que comparan el comportamiento de estructuras de base fija con el de las mismas estructuras, pero con diferentes sistemas de aislamiento de base.
Se consideran edificios con sistema de aislamiento histeretico y friccional, se desarrollan sus e... more Se consideran edificios con sistema de aislamiento histeretico y friccional, se desarrollan sus ecuaciones del movimiento y se describen procedimientos de calculo numerico de la respuesta del sistema aislado. A continuacion se estudia la posibilidad de desarrollo de sistemas de aislamiento de base activos (sistemas hibridos). Despues de describir una nueva estrategia de control activo que se propone, se incluye un estudio numerico de simulacion de la respuesta sismica de edificios con sistemas de control hibrido.
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