Damper distribution

For further understanding the performance of the SCISR by comparison, the preparation experiments are also carried out simultaneously in a stirred tank reactor (STR) with an effective volume of 0.6x10 m3, the structure of which is indicated in Fig. 13.1. In order to mimic industrial conditions, the STR is equipped with three dampers distributed uniformly along the circle the stirrer is a flat paddle. 

For both indices instead different damper distributions can be obtained using different earthquake records that can be caused by the different frequency content of each earthquake (Figure 4). Hence it has been found that the optimal distributions obtained with J3 and J4 as objective functions strongly depend on the nature of the earthquake record at the site. Hence, the optimal damper distribution for seismic excited buildings can be obtained by minimizing J4 using the design earthquake of the particular site. 

Figure 9. Damper distributions using the maximum interstory drift (J4)...

Figure 10. Damper distribution using the maximum absolute acceleration (J3) for different search algorithms...

The base shear coefficient normalized with respect to the total weight ofthe building is shown in Figure 13, comparing the uncontrolled structure with the uniformly distributed dampers and the two optimal distributions obtained using the maximum interstory drift (J4) and the maximum absolute acceleration (J3) performance indices. A reduction of the base shear is observed for all the earthquake records that is slightly improved when also the optimal damper distributions are considered. 

It has been observedthat when the DOFs ofthe building are reduced such as in the 6 story building, then SS, WOBI and ESPS search methods bring to the same damper distribution for various objective functions considered. However when the complexity of the building increases such as in the 30 story building, then the applications... 

Aydin, E., Boduroglu, M. H., Guney, D. (2006). Optimal damper distribution for seismic rehabilitation of planar building stmctures. Engineering Structures, 29(2). 

Of all the advanced placement techniques tested here, the Lavan method achieves the best performance with the least complexity and time expended to achieve the damper distribution scheme. However, the differences between the advanced techniques should not be exaggerated, as all three produced similar placement schemes and extremely similar drift and acceleration results. 

It can be concluded that the results obtained by both methods yield similar dampers distributions within the frame. Differences between the optimal values of damping coefficients, obtained as the result of optimization procedures, are partially affected by an incremental way of distribution of the damping coefficients in the sequential optimization method. Moreover, in the PSO method the values ofthe damping. parameters must be positive for every damper. Dining the iteration process, negative or zero values of parameters c. were substituted by c. andnormal-... 

The optimal damper distributions in buildings are found for various objective functions. The weighted sum of amplitudes of the transfer functions of interstorey drifts and the weighted sum of amplitudes of the transfer functions of displacements evaluated at the fundamental natural frequency of the frame with the dampers are most frequently used as the objective function. The optimization problem is solved using the sequential optimization method and the particle swarm optimization method. Several numerical solutions to the considered optimization problem are presented and discussed in detail. 

The interaction between the structure and dampers distributed throughout the structure. 

Wongprasert, N., Symans, M. D. (2004). Application of a genetic algorithm for optimal damper distribution within the nonlinear seismic benchmark building. Journal of Engineering Mechanics, 130(A), 401-406. doi 10.1061/ (ASCE)0733-9399(2004)130 4(401)... 

Although spatially unequal damper distribution on the two towers can lead to the... 

The algorithm includes a set of successive improving steps (Agranovich, 2010). At each of these steps a new floor becomes active according to the above described assumption, and the dampers distribution at the active floors is updated. After updating the number of active floors structural response to the artificial ground motion is simulated. Then, based on the peak control forces at every story, the number of dampers per each of the active floors is obtained. 

Here an efficient evaluation method using the robustness function with respect to the constraint on seismic performance is presented and explained by taking advantage of the sophisticated uncertainty analysis method called the URP method. A planar shear building model with passive viscous dampers is used for the robustness analysis (see Fig. 1). By comparing the robustness functions for various damper distributions, a preferable damper distribution is investigated to enhance the robustness of the building model under various uncertainties of structural parameters. 

In this section, the robustness functions defined by Eq. 3 for various damper distributions are evaluated by the URP method. Figure 11 shows the comparison of maximum interstory drifts of the building structure without dampers for three recorded ground motions. It may be observed from Fig. 11 that the interstory drift is maximized at upper stories above the 15th floor. For enhancing the seismic performance of the building structure, let us consider three different... 

The optimum damper distribution has been derived by the optimization algorithm developed in the reference (Fujita et al. 2010b) to minimize the maximum amplitude of interstory-drift transfer function. 

Taft EW (1952). Since the optimal damper distribution is aimed at suppressing the maximum amplitude of interstory-drift transfer functitm at the fundamental natural circular frequency, the drastic response reduction can be achieved for the excitation, such as Taft EW (1952), whose predominant frequency is resonant to the fundamental natural circular frequency of the objective building structure. It can be observed from Fig. 14b that if the performance criterion with respect to the maximum interstory drift is given by 0.03 [m], the robustness function a is nearly... 

Robust Control of Building Structures Under Uncertain Conditions, Fig. 13 Various damper distributions (a) uniform, (b) llth-20th story, (c) optimum... 

Figure 16 shows the degree of robustness of building structures with different damper distributions in terms of different robustness functions. If the maximum interstory drift is specified as 0.03 [m], the building structure with the optimum... 

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