On the use of fixed point theory to design coupled core walls
The use of Fixed Point Theory (FPT) to optimize the design of coupling beams in coupled core wall (CCW) systems is demonstrated. The basis for optimization is minimizing the transmissibility of horizontal ground motion by appropriately linking two coupled wall piers having different dynamic properties with beams having appropriate stiffness and damping characteristics. Using 21 example CCW structures illustrating a range of pier properties, it was shown that the resulting optimization of coupling stiffness is quite small and other design considerations will require stiffer, non-optimal coupling beams. Nonetheless, the potential to leverage the small amount of coupling available in a ‘slab-coupled’ series of wall piers in order to reduce transmissibility is suggested by the findings of this study.
Parametric Study of Coupled Wall Behavior—Implications for the Design of Coupling Beams
Coupled walls are known to be efficient lateral load resisting systems; however, the relationship between their global and local behavior is not well understood and has been shown to result in structural systems having excessive internal deformation or strength demands on their component substructures. In order to investigate appropriate parameters for identifying efficient coupled wall geometries, an initial parametric study of over 2000 coupled wall geometries is reported. These analyses permitted the evaluation of the sensitivity of the structural response to various geometric parameters. The objective of this study is to investigate the elastic response parameters of coupled wall structures and to identify parameters that will permit an accurate initial estimate of the global behavior of a coupled system, the local behavior of the coupling beams and the interaction between the global and local behaviors. Using elastic analysis and gross section properties, the role of representative geometric parameters in the response of coupled structures is illustrated. The effect of using various code-prescribed reduced section properties is also discussed. The critical role of the coupling beam design is also illustrated.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.