Adaptable dual control systems. a comparative parametric analysis

Phocas, Marios C.; Sophocleous, T. L.

doi:10.2495/safe-v2-n3-280-296

Cited by 3 publications

(6 citation statements)

References 15 publications

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“…They determined the optimal policy N such that the long-run expected profit per unit time is maximized and showed that the model for the multistate system forms a general monotone process model which includes the geometric process model as a special case. Lam [22] reported a maintenance model for two-unit redundant system with one repairman. Under this model, he studied two kinds of replacement policy, respectively based on the number of failure and the work age for two units.…”

Section: Introductionmentioning

confidence: 99%

Reliability Model for Warm Standby System under Consideration of Replace Time

Yang¹

2016

IJHIT

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There are two effective ways to maintain the system to perform a high or required level of reliability and availability: one is spare units for key units; the other is several maintainers for the system. To solve reliability indexes of complex mechanical system under these assumptions, a system model was established, which consists of two dissimilar subsystems in series and each subsystem is warm standby system, which consists two same units. We divided maintain time into replace time and repair time. In this paper, we arrange two maintainers for the system, and take 'the system in normal states' as maintenance strategy. Taking high efficiency of cooperative maintainers into account, the formula of system availability, system reliability, rate of occurrence of failure (ROCOF) and mean time to first failure (MTTFF) can be derived by operating the state transition probability matrix. This research provides evidence for further studies of complex mechanical system reliability.

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Section: Introductionmentioning

confidence: 99%

Reliability Model for Warm Standby System under Consideration of Replace Time

Yang¹

2016

IJHIT

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“…The design of the bracing-damper mechanism is based on the selection of the dampers stiffness, k d and yield force, P y , so that maximum hysteresis is achieved [14]. In addition the maximum base shear and the relative displacements of the controlled system hold in bounds with the respective responses of the primary system.…”

Section: Model For Dynamic Analysismentioning

confidence: 99%

“…Based on three representative international strong earthquake motions of differing frequency contents presented in In the numerical analyses the cables were modelled as frame objects with zero compression limit and no prestress. The hysteretic damper that exhibits a nonlinear behaviour was modelled with a link element, assigned to follow the uniaxial plasticity Wen model of hysteresis for the degree of freedom that corresponds to shear deformation [14]. In the current study the bracing was modeled with cable elements.…”

Section: Model For Dynamic Analysismentioning

confidence: 99%

“…ADCS is only responsible for the earthquake forces and enables in all cases the elastic response of the primary system. Based on three international strong ground motions with different frequency contents, ADCS effective response behaviour with regard to energy dissipation maximization, without increase of the system's maximum base shear and relative displacements have been verified in [14]. In the studies conducted the cables had a constant diameter and were modelled as frame objects with zero compression limit.…”

Section: Introductionmentioning

confidence: 99%

“…In the present study an ADCS-configuration of a portal-and a chevron bracing, ADCS2, assigned with the selected mechanical characteristics of the hysteretic damper, i.e. elastic stiffness and yield force, in [14] is further investigated in its earthquake responses with different cable stiffness values and a constant pretension stress. Respective numerical nonlinear analyses conducted exemplify the earthquake performance of the bracing-damper mechanism, while ensuring a linear elastic resistance of the tension-only members.…”

Section: Introductionmentioning

confidence: 99%

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Cable bracing design in adaptable dual control systems

Phocas

Sophocleous

2013

WIT Transactions on the Built Environment

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Structural control through energy dissipation systems has been increasingly implemented internationally in the last years and has proven to be a most promising strategy for earthquake safety of structures. The present paper examines an alternative control system development for achieving dynamic structural adaptability. The prototype control system consists of a hysteretic energy dissipation device of triangular steel plates and a tension-only bracing with closed circuit realized through implementation of rotating discs at the braces connections. A typical configuration design of the kinetic mechanism consists of a portal-and a chevron cable bracing. Based on three representative international strong earthquake motions of differing frequency contents, parametric dynamic analyses of the SDOF system responses mainly characterized by high energy dissipation have been performed by the authors in previous studies with regard to the mechanical characteristics of the hysteretic damper, i.e. elastic stiffness and yield force, whereas the cables were modelled as frame objects with zero compression limit. In the present study the optimum controlled system is further investigated in its earthquake responses with different cable stiffness values and a pretension stress. The respective numerical nonlinear analyses conducted exemplify the earthquake performance of the bracing-damper mechanism, while a linear elastic resistance of the tension-only members is verified.

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Dual control connections in frames for earthquake resistance

Phocas¹,

Sophocleous²

2015

WIT Transactions on the Built Environment

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The behaviour optimization of structures under severe dynamic actions, such as earthquakes, is being increasingly aimed at the control of the stiffness and damping properties of structures. The present paper examines an alternative control mechanism for achieving dynamic structural adaptability. To achieve a larger degree of freedom in the members' control design, a novel dual connection of the primary members of the frame is proposed, which can initially "filtrate" the moment transmission at the joints. The connection consists of elastomeric material fixed at the primary joint areas and the lower column areas of three frames. The elastomeric shear connections are activated from the beginning of the horizontal excitations of the frame. Consequently, the stiffness of the primary system is no longer restricted to the geometric relations of the connected members. The elastic connection enables, primarily, a displacement increase of the structures and a slight increase of their energy dissipation performance. Based on three representative international strong earthquake motions of differing frequency contents, respective numerical nonlinear analyses of a SDOF system exemplify the earthquake performance of the controlled frames with elastic connections. In perspective, the stiffness control concept may enable further objectives in the design to be achieved for a stepwise adaptation by the primary system to the external acting forces through an increase of its damping properties.

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Adaptable dual control systems. a comparative parametric analysis

Cited by 3 publications

References 15 publications

Reliability Model for Warm Standby System under Consideration of Replace Time

Reliability Model for Warm Standby System under Consideration of Replace Time

Cable bracing design in adaptable dual control systems

Dual control connections in frames for earthquake resistance

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