Optimal Damper Placement Research Articles

Robust optimal damper placement based on robustness index simultaneously considering variation of elastoplastic design criteria and input level

Dampers should be installed at appropriate quantities and locations to control building vibrations against excitations such as earthquakes and wind loads. One of the objectives of the structural optimization problem for damper placement is to minimize the initial cost of damper installation to satisfy various structural constraints under a set of input levels and target performance values. However, it is arbitrary what input levels should be used in the design, and it is also necessary to account for various uncertainties in the inputs and structural properties. This study presents a new method for assessing the robustness of building structures with design variables while simultaneously considering various phases of structural performance criteria and input amplitudes. The proposed robustness index is a multidimensional function that can take into account the influence of different input levels on the structural performance. In this paper, the proposed new robustness index is applied to the robust optimal design of the damper placement, where the damping coefficient of the linear oil damper added to the building is uncertain. The worst resonant seismic motion for the building is investigated based on the critical double impulse method and its equivalent one-cycle sine wave, which is used as the input seismic motion. By applying the equivalent one-cycle sine wave to the structural response analysis with variations in the input velocity amplitude, the proposed robustness index is effective in comprehensively assessing the relationships between the input velocity amplitude of the seismic motion and the upper response limit of the structure under the variation of the damping coefficient of the oil damper. The comprehensive and efficient evaluation of these relationships enables a more detailed assessment of the influence of uncertainties in design variables on structural performance. In the numerical examples, the optimal damper placement for a 12-story building model is discussed based on the robustness and structural performance of both acceleration and story ductility distribution.

Performance enhancement of damaged RC structures with viscoelastic dampers: Damage assessment and optimal placement

Evaluating the performance degradation of the earthquake-damaged structure and optimizing the placement of dampers is important for retrofitting post-earthquake structures. In this study, a damage evolution model is developed to evaluate the degradation of strength, stiffness, and energy dissipation capacity for earthquake-damaged structures. The proposed damage model is validated using previous experimental results based on the nonlinear finite element analysis. Then, research on the optimal design of damper parameters and quantity is carried out. Considering the optimization range of earthquake-damaged structures, a genetic algorithm with multi-objective functions is developed to determine the optimal placement of viscoelastic dampers in damaged structures. The results demonstrate that the proposed damage model can effectively describe the performance degradation of damaged structures. The control effects of the acceleration response increase exhibited a maximum enhancement of 3.38 times after accounting for the optimization range of earthquake-damaged structures. The optimization results of the multi-objective function with the optimization range are better aligned with the objectives of designers.

Fragility-based framework for optimal damper placement in low-rise moment-frame buildings using machine learning and genetic algorithm

Commonly, seismic fragility is used as an assessment tool rather than a design constraint for existing building structures. In addition, the degree of seismic fragility safety margin after retrofitting existing structures is usually unknown during the early retrofit design stage. The current study proposes a framework that allows the designer to assign the preferred seismic fragility margin as a design variable before retrofit of a structure using soft computing techniques. In addition, it provides the design damping ratio to achieve the optimal damper capacity distribution required for retrofit. To this end, a machine learning model (MLM) is used to construct safety margin curve (SMC) graphs for the structural system considering different limit states to obtain the design damping ratio. This MLM is trained with a wide range of structural systems subjected to various levels of ground motion intensities for predicting seismic responses of the system. The main role of the MLM and SMC is to provide a reasonable approximate range for damper capacity in each story to reduce the computational time required for the optimization process. After that, a genetic algorithm (GA) optimization process is implemented to obtain the optimum capacities of the energy dissipation devices (EDDs) required for retrofitting the structure using the design damping ratio obtained from the SMC. Displacement-dependent EDDs are used in the current study because of their effectiveness in dissipating seismic energy. The EDDs are arranged such that the seismic demands are controlled to achieve the required basic seismic safety objective maintaining the optimal EDD capacity for each story. The reliability and robustness of the framework are investigated using various case-study examples and validated by comparing the results with those obtained from nonlinear time history (NLTH) and nonlinear static methods. The proposed framework is validated for low-rise moment-resisting frame buildings that can be represented using a single degree of freedom (SDOF) system. The framework is expected to enable researchers and engineers to effectively implement the required level of seismic safety in retrofitted structures with less computational cost and allows the designer to select the most suitable retrofit scheme considering multiple limit state criteria checks.

Inverse optimal damper placement via shear model for elastic–plastic moment-resisting frames under large-amplitude ground motions

A new method of optimal damper design is presented for elastic–plastic planar frame structures under large-amplitude earthquake ground motions. The transformation of a moment frame into the 1st-mode equivalent shear mass system leads to an efficient search of the optimal damper placement along the building height for the elastic–plastic moment frame. In the optimization procedure, a linear elastic bare frame is transformed into the 1st-mode equivalent shear mass system first. Then the optimization of the damper placement is conducted for the elastic shear mass system. After that, the damped shear mass system is inversely transformed into the elastic–plastic moment frame with the added dampers. This inversely transformed damper system in the moment frame is employed as an initial design and the local search-based optimization is conducted for the efficient distribution of dampers not only along the building height, but also among the different bay. The proposed method greatly reduces the computational task in the whole optimization procedure because only a limited number of time-history response analyses is required for elastic–plastic moment frames. It is demonstrated through numerical examples that the proposed method efficiently provides the damper designs with high accuracy. Finally, the importance of using the large-amplitude ground motions for damper optimization is demonstrated through the incremental dynamic analysis (IDA) for the optimally designed models.

Robust Optimal Damper Placement of Nonlinear Oil Dampers With Uncertainty Using Critical Double Impulse

A new robust method for optimal damper placement is presented for building structures under the critical double impulse. Oil dampers are treated here as representative supplemental dampers to control the seismic response of high-rise buildings. Such oil dampers usually obey a bi-linear force-velocity relation in controlling the maximum damping force through a relief mechanism to avoid the occurrence of excessive design forces in surrounding frames. The influence of uncertainty in characteristics of those bi-linear oil dampers on building structural safety is investigated. For the efficient evaluation of dynamic performance, the resonant critical double impulse is used as the base input instead of actual earthquake ground motions. Since the critical double impulse is determined to maximize the input energy to the objective building by changing the second impulse timing, uncertainties in input ground motions can be taken into account in a robust manner. To consider these various uncertainties, the robustness function based on the Info-Gap model is used in the robust optimization to assess structural performance variations caused by various uncertainties in the structural design phase. In this paper, a new innovative objective function in the robust optimal damper placement problem is proposed to enhance the robustness of structural performance under the variation of structural parameters by comparing the robustness function of the robust design with that of an ordinary optimal damper placement without considering uncertainties. Numerical examples of the robust optimal design of linear and bi-linear oil damper placements are shown for 10-story and 20-story planar building frame models. Structural performances of the robust optimal design to the conventional design earthquake ground motions are examined to investigate the validity of using the critical double impulse in the structural design under uncertainties.

Performance-based optimal distribution of viscous dampers in ‎structure using hysteretic energy compatible endurance time excitations

Performance-based optimization of energy dissipation devices in structures necessitates massive and repetitive dynamic analyses. In the endurance time method known as a rather fast dynamic analysis procedure, structures are subjected to intensifying dynamic excitations and their response at multiple intensity levels is estimated by a minimal number of analyses. So, this method significantly reduces computational endeavors. In this paper, the endurance time method is employed to determine the optimal placement of viscous dampers in a weak structure to achieve the desired performance at various hazard levels, simultaneously. The viscous damper is one of the energy dissipation systems which can dissipate a large amount of seismic input energy to the structure. To this end, hysteretic energy compatible endurance time excitation functions are used and the validity of the results is investigated by comparing them with the results obtained from a suite of ground motions. To optimize the placement of the dampers, the genetic algorithm is used. The damping coefficients of the dampers are considered as design variables in the optimization procedure and determined in such a way that the sum of them has a minimum value. The behavior of the weak structure before and after rehabilitation is also investigated using endurance time and nonlinear time history analysis procedures in different hazard levels.

Influence of soil-structure interaction (SSI) on optimal design of passive damping devices

Recently, the interest in research for optimization of viscous dampers in design of buildings has been increasing. In this study, the effect of soil-structure interaction has been taken into account for the purpose of optimal design of viscous dampers. A damper optimization method based on a target damping ratio and interstorey drift ratio found in literature has been adapted for a building structure model considering different types of sandy soils. While passive constraints have been taken as upper and lower limits of each damper, active constraints have been considered as a target damping ratio in terms of damping coefficients. The proposed algorithm includes time history analyses that test the designer’s optimal design. Interstorey drift ratios under design earthquakes have been checked at each design step. The first and second mode responses have been considered separately. According to the results obtained from this study, the negative impact of sandy soils on the dynamic behavior of superstructures can be overcome by optimal placement of dampers in buildings. The results of the analyses have shown that soil effects should be taken into account in solving damper optimization problems.

Comparative investigation on optimal viscous damper placement for elastic-plastic MDOF structures: Transfer function amplitude or double impulse

The effectiveness of the optimal viscous damper placement for elastic-plastic multi-degree-of-freedom (MDOF) structures under the critical double impulse is demonstrated through the comparison with the optimal damper placement for elastic MDOF structures designed with respect to transfer function amplitudes at natural frequencies. The method for optimal viscous damper placement was proposed for elastic-plastic MDOF structures subjected to the critical double impulse as a representative of near-fault ground motions in the previous paper [1]. The double impulse is composed of two impulses with opposite directions and the critical interval is determined by using the criterion on the maximum input energy. The critical timing of the second impulse was found to be the timing which requires the vanishing of the sum of the restoring force and the damping force in the first story. Three models with different story stiffness distributions of main structures are treated to demonstrate the effectiveness of the optimal viscous damper placement under the critical double impulse. The double impulse pushover (DIP) procedure proposed in the previous paper for determining the input velocity level of the critical double impulse is examined further in this paper. It is demonstrated that the optimal viscous damper placement for elastic-plastic MDOF structures under the critical double impulse is more effective for pulse-type recorded earthquake ground motions than the optimal damper placement designed with respect to transfer function amplitudes at natural frequencies because several higher modes arising in the elastic-plastic response under pulse-type recorded earthquake ground motions can be well controlled by the design for the double impulse.

The optimal damper placement configuration for three-dimensional RC building

During an earthquake, high-rise buildings attempt to dissipate energy by generating swaying motion, which causes inevitable building damage. The dampers or passive energy dissipation devices can significantly diminish the energy emitted by earthquakes and reduce building damage accordingly. Especially for high-rise building structures constructed in an earthquake-prone area, it is necessary to install a sufficient number of dampers to reduce the building response. The passive energy dissipation devices present such an optimal performance depends on their locations in the building structures. Therefore, the objective of this paper is to observe an optimal placement configuration of passive energy devices lest excessive installment of the devices. The proposed approach is performance-based optimizations, which seismic performance of buildings considered is story drift of the building. This study focuses on optimizing fluid viscous dampers (FVD) placement incorporated into three-dimensional (3D) regular RC building structure. The result shows that fluid viscous dampers (FVD) when incorporated into three-dimensional of regular RC building structures can modify the performance of the building to fulfill the code standard of allowable drift ratio. It will be then suggested to be prevention acts to improve the performance of high-rise buildings under earthquakes excitation. Hence, the protection of the occupants therein can be accomplished.

Optimum placement of supplementary viscous dampers for seismic rehabilitation of steel frames considering soil–structure interaction

SummaryIn this paper, the significance of soil–structure interaction (SSI) in optimal placement of viscous dampers in steel frames is studied. Optimal placement of dampers is determined with the purpose of achieving performance objectives at three hazard levels using genetic algorithm optimization. Endurance time method is used for seismic nonlinear response analysis of the fixed‐base and SSI included frames. The soil beneath the structures is considered as a homogeneous elastic half‐space, and the soil–structure systems are modeled by the substructure method. Results indicate that at low excitation intensities, consideration of SSI results in maximum drift ratio reduction at all stories of the frames. At higher intensity levels, more drift is observed in the upper stories of the soil–structure systems in comparison with the fixed‐base frames. Higher damping in the upper stories is required to optimally rehabilitate soil–structure systems as compared with the corresponding fixed‐base ones. In most of the frames, SSI leads to the reduction of total required damping. However, the optimal damper placement based on the analysis of fixed‐base frames can be unconservative due to changes in damping distribution patterns.

Simultaneous Approach to Critical Fault Rupture Slip Distribution and Optimal Damper Placement for Resilient Building Design

The uncertainties in ground motions may result from several factors, e.g. (i) the fault rupture process, (ii) the wave propagation, (iii) the site amplification from the earthquake bedrock to the ground surface. The uncertainty in the fault rupture slip is taken as a main factor of uncertainties in the present paper and the critical fault rupture slip distribution causing the maximum structural response is found by using the stochastic Green’s function method as a generator of ground motions. Then, a multi-degree-of-freedom (MDOF) building structure is introduced as a model structure and an optimal damper placement problem is discussed for the critical ground motion. The main topic in this paper is the simultaneous determination of the critical fault rupture slip distribution and the optimal damper placement. The sequential quadratic programming method is used in the problem of critical fault rupture slip distribution and a sensitivity-based method is introduced in the optimal damper placement problem. Furthermore, the robustness for the maximum interstory drift in MDOF building structures under the uncertainty in fault rupture slip distributions is presented for resilient building design by using the robustness function. Since the critical case leads to the most unfavorable structural response, the proposed method can provide structural designers with a promising tool for resilient building design.

Effect of Multiple Tuned Mass Dampers for Vibration Control in High-Rise Buildings

Tuned mass dampers (TMDs) are one of the strategies implemented in the field of structural vibration control. Most researchers have only focused on the control of one specific mode of vibration by idealizing the structure as a single-degree-of-freedom system. From a practical point of view, the use of a single large TMD within a structure would adversely affect the architectural appeal, usable space, and ease of installation. This study introduces a multiple tuned mass damper (MTMD) system, which is simple and more effective than a conventional single TMD system. The system consists of multiple smaller dampers distributed within the structure either uniformly, varying linearly, or based on the judgment of the designer. TMDs tuned to the first, second, and third natural frequencies are used to control vibrations, thus enabling a wider bandwidth of vibration control and attaining remarkable reductions in floor displacements, floor accelerations, and base shear. A MTMD system was investigated for different base excitations, namely harmonic and seismic. A three-degrees-of-freedom frame model and three mass dampers tuned to all three natural frequencies of the system were fabricated. This building model was studied experimentally and analyzed to investigate the effect of harmonic base excitation on structures. Compared with single TMD systems, the performance of the proposed MTMDs system was found to be excellent in controlling displacements. A five-degrees-of-freedom structure was analyzed for seismic excitation to study the effect of two mass dampers tuned to first two natural frequencies with a mass ratio of 5%. The proposed system significantly reduced the displacement, acceleration, and base shear response at the next-higher-order natural frequency beyond the fundamental. The responses of the structures were compared to assess the optimal placement of dampers to attain highest performance. Vibration control by multiple TMDs was found to be more efficient when dampers are strategically placed on the floors, with the maximum amplitude in the mode shapes corresponding to the respective tuning frequencies.

Optimal Design and Distribution of Viscous Dampers for Shear Building Structures Under Seismic Excitations

Viscous dampers (VDs) are effective and widely used passive devices for the protection of civil structures, provided that appropriate design is carried out. For this purpose, an optimal design and optimum distribution of VDs method is presented for a shear building under the critical excitation by using random vibration theory in frequency domain. In the optimization, by using Differential Evolution (DE) algorithm, the and top floor displacement are evaluated as objective functions taking into consideration upper and lower limits of VDs damping coefficients, so that optimal damper placement and properties of shear building can be determined. In this design, VDs-shear building system is tested under three different ground motions being compared to some methods in the literature and uniformly distributed VDs placed at each story. It is shown that, the results of study are both compatible and very successful in reducing the response of structure under the different ground motions.

Optimal Viscous Damper Placement for Elastic-Plastic MDOF Structures Under Critical Double Impulse

A new method for optimal viscous damper placement is proposed for elastic-plastic multi-degree-of-freedom (MDOF) structures subjected to the critical double impulse as a representative of near-fault ground motions. The double impulse consists of two impulses with different directions and the critical interval between those two impulses is characterized by the criterion on the maximum input energy that is expected to lead to the maximum deformation. The critical timing of the second impulse is the timing at which the sum of the restoring force and the damping force in the first story attains zero. The objective function and constraint in terms of the maximum interstory drift along the building height or the sum of the maximum interstory drifts in all stories are selected and the corresponding optimization algorithm based on time-history response analysis and sensitivity analysis is investigated. Since the objective function in terms of the sum of the maximum interstory drifts in all stories is superior to the objective function in terms of the maximum interstory drift along the building height, it is employed in this paper. A new concept of double impulse pushover (DIP) is proposed for determining the input velocity level of the critical double impulse. It is demonstrated that the combination of two algorithms, one for effective reduction of the overflowed maximum interstory drift via the concentrated allocation of dampers and the other for effective allocation of dampers via the use of stable objective function, is effective for finding a stable optimal damper placement.

Optimal Damper Placement Using Combined Fitness Function

Passive control of structures represents practical concept and qualitative change of the design and construction of new seismically resistant structures and strengthening of existing ones. The best distribution obtained by the minimization or maximization of the defined structural responses is achieved by optimal placement of the different types of control devices in structures. In this paper will be presented the procedure for optimal placement of viscous damping device (PDD – Prestressed Damping Device-PDD) space distributed in structure for controlling the structural response due to seismic excitation. For the purpose of determination of the optimal location of the PDDs, 3D five story steel frame structure has been designed according to the Eurocode 3 and Eurocode 8 requirements. Nine previously defined initial configurations have been used as a starting point in the process of optimization. The desired performance has been defined using the derivate fitness function combined from the inter-story drift and energy dissipated ratio by PDDs vs input energy in the structure in two directions x and y. The value of the fitness function has been used to rank and quantify the optimum of the particular solution among all other solutions in the optimization process. Numerous nonlinear analyses have been conducted and a lot of analytical results have been collected in order to confirm the validity and the application of the presented procedure including the fitness function in any steel structure.

Optimal placement of metallic dampers for seismic upgrading of multistory buildings based on a cost‐effectiveness criterion using genetic algorithm

SummaryIn this paper, an optimal placement methodology for metallic dampers is proposed to upgrade the seismic performance of multistory buildings. Most previous studies on optimal damper placement (ODP) problems have been focused on minimizing the seismic responses, whereas the present study aims to utilize the minimum total cost of dampers to achieve a prescribed level of seismic response. To this end, the optimization objective is constructed based on a cost‐effectiveness criterion, and the optimization constraint is defined based on a desired level of seismic response. An improved integer‐coded genetic algorithm is presented for solving the ODP problem. A 16‐story shear building is illustrated to verify the proposed optimal placement methodology. It is shown that the proposed methodology can be used to achieve the predetermined performance level while minimizing the retrofitting cost. Moreover, different algorithms, objective functions, and levels of accuracy on the optimization are also compared. Finally, a two‐step optimization approach is proposed for achieving better placement schemes with less computational efforts.

Optimal damper placement research

Nowadays increased noise and vibration pollution on technopark and research laboratories territories, which is negatively influencing on production of high-precision measuring instruments. The problem is actual for transport hubs, which experience influence of machines, vehicles, trains and planes. Energy efficiency is one of major functions in modern road transport development. The problem of environmental pollution, lack of energy resources and energy efficiency requires research, production and implementation of energy efficient materials that would be the foundation of environmentally sustainable transport infrastructure in road traffic. Improving the efficiency of energy use is a leading option to gain better energy security, improve industry profitability and competitiveness, and reduce the overall energy sector impacts on climate change. This paper has next indirect goals. Research impact of vibration on constructions, such as bus and train stations, terminals, which are mostly exposed to oscillation. Extend the buildings operation by decreasing the negative influence. Reduce expenses on maintenance and repair works. It is important not to forget about seismic protection, which is actual nowadays, when the safety stands first. Analysis of devastating earthquakes for last few years proves reasonableness of application such systems. The article is dedicated to learning dependence of damper location on natural frequency. As a model for analyze was simulated concrete construction with variable profile. We used program complex Patran for analyzing the model.

OPTIMAL PLACEMENT OF HYSTERETIC OR VISCOUS DAMPER BASED ON THE INCREMENTAL INVERSE PROBLEM

Abstract. Structural control system aims to improve the protection of buildings and civil structures, occupants and contents from the destructive forces of nature due to earthquakes, wind and waves. Control techniques can be classified according to how the system manipulates, absorbs and dissipates the imposed energy. Passive damping system absorbs or consumes a portion of the input energy, reducing energy dissipation on primary structural members and does not require an external power source. In this work the efficiency of four Matlab programmed routines in terms of time or computational cost and flexibility according to the type of damper will be assessed. Two techniques were evaluated: (a) An analytical procedure known as incremental inverse problem for redesign of structural system with a hysteretic damping system for target transfer functions and (b) to apply an efficient and systematic procedure for to find the optimal damper placement to minimize the sum of amplitudes of the transfer functions evaluated at the undamped fundamental natural frequency of a structural system subject to a constraint on the sum of the damping coefficients of added dampers. Keywords: Optimal placement of dampers, Hysteretic and viscous devices, Incremental inverse problem, Transfer function, Passive control

Optimal damper placement in hybrid control system of multiple isolation and building connection

An algorithm for optimal damper placement is proposed in a hybrid control system of multiple isolation and building connection. Such innovative hybrid control building system has been proposed recently. It is a great concern whether the seismic displacement response at the base-isolation layer of the existing base-isolated buildings may be amplified under long-period and long-duration ground motions. In order to enhance the robustness on the seismic performance of those base-isolated buildings, a novel hybrid system of multiple isolation and building-connection has been proposed and compared with other structural systems such as an independent multiple isolation system, a hybrid system of base-isolation and building-connection in the previous paper. It has been made clear that such hybrid control system possesses a remarkable performance for various types of earthquake ground motions. After the investigation of the effective location of the middle isolation story, a sensitivity-based optimisation algorithm is proposed for optimal connection damper placement in such hybrid control system.

Optimal damper placement in hybrid control system of multiple isolation and building connection

Optimal damper placement in hybrid control system of multiple isolation and building connection