Wind Loads on Structures, and Energy Dissipation Systems Optimization

2019 ◽  
pp. 128-149
Author(s):  
Aboubaker Gherbi ◽  
Mourad Belgasmia
Keyword(s):  
Energy Dissipation ◽  
Optimal Design ◽  
Structural Damage ◽  
Optimization Methods ◽  
Wind Effect ◽  
Civil Structures ◽  
Fluid Viscous Dampers ◽  
Tall Structures ◽  
External Loads ◽  
Efficiency And Reliability

Wind has a great impact on civil structures. It is considered a dynamic and random phenomena and it plays an important role in the design of tall structures. Existing buildings with certain height must resist wind effect. Many researchers have developed theories and schemes that consider more thoroughly wind components and the influence of its turbulence on buildings. It is known that any structure inherently dissipates and absorbs energy due to external loads thanks to its inherent damping. In order to improve this capacity and limit structural damage, fluid viscous dampers are commonly used for structural protection; they have confirmed their efficiency and reliability. Many researchers have investigated their effect by inserting them in the structure; some of the optimization methods for the design of these dampers previously used will be discussed. Finally, an effective method for optimal design of additional dampers will be illustrated by an example and discussion.

Passive Dampers

2021 ◽  
pp. 158-169
Keyword(s):  
Energy Dissipation ◽  
Dynamic Behavior ◽  
Optimal Choice ◽  
Damping Coefficient ◽  
Severe Damage ◽  
Civil Structures ◽  
Fluid Viscous Dampers ◽  
Story Drift ◽  
Rc Building ◽  
Passive Dampers

Civil structures are subjected to various types of loading, which induce severe damage to the structures. Many techniques have been developed for structural rehabilitation; one of the emerging technologies is the use of energy dissipation systems such as fluid viscous dampers (referred to hereafter by FVD). In this chapter, the effect of these devices on the dynamic behavior of an RC building is investigated, with an optimal choice of the linear FVD parameter (i.e., damping coefficient), using a simplified and effective approach. It was found that the maximum inter-story drift of the analyzed retrofitted structures can be significantly reduced compared to the original ones.

scholarly journals A Comprehensive Study on the Optimal Design of Magnetorheological Dampers for Improved Damping Capacity and Dynamical Adjustability

Actuators ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 64
Author(s):  
Liankang Wei ◽  
Hongzhan Lv ◽  
Kehang Yang ◽  
Weiguang Ma ◽  
Junzheng Wang ◽  
...  
Keyword(s):  
Optimal Design ◽  
Optimization Methods ◽  
Design Stage ◽  
Damping Capacity ◽  
Damping Force ◽  
Simulation And Optimization ◽  
Damping Characteristics ◽  
Hysteretic Characteristics ◽  
Gap Width ◽  
Comprehensive Study

Purpose: We aim to provide a systematic methodology for the optimal design of MRD for improved damping capacity and dynamical adjustability in performing its damping function. Methods: A modified Bingham model is employed to model and simulate the MRD considering the MR fluid’s compressibility. The parameters that describe the structure of MRD and the property of the fluid are systematically examined for their contributions to the damping capacity and dynamically adjustability. A response surface method is employed to optimize the damping force and dynamically adjustable coefficient for a more practical setting related to the parameters. Results: The simulation system effectively shows the hysteretic characteristics of MRDs and shows our common sense understanding that the damping gap width and yoke diameter have significant effects on the damping characteristics of MRD. By taking a typical MRD device setup, optimal design shows an increase of the damping force by 33% and an increase of the dynamically adjustable coefficient by 17%. It is also shown that the methodology is applicable to other types of MDR devices. Conclusion: The compressibility of MR fluid is one of the main reasons for the hysteretic characteristics of MRD. The proposed simulation and optimization methods can effectively improve the MRD’s damping performance in the design stage.

scholarly journals Seismic Damage Model of Bridge Piers Subjected to Biaxial Loading Considering the Impact of Energy Dissipation

2019 ◽  
Vol 9 (7) ◽  
pp. 1481 ◽  
Author(s):  
Shangshun Lin ◽  
Zhanghua Xia ◽  
Jian Xia
Keyword(s):  
Energy Dissipation ◽  
Structural Damage ◽  
Biaxial Loading ◽  
Mechanical Performance ◽  
Damage Model ◽  
Damage Index ◽  
Seismic Damage ◽  
Bridge Piers ◽  
Dissipated Energy ◽  
The Impact

The large degradation of the mechanical performance of hollow reinforced concrete (RC) bridge piers subjected to multi-dimensional earthquakes has not been thoroughly assessed. This paper aims to improve the existing seismic damage model to assess the seismic properties of tall, hollow RC piers subjected to pseudo-static, biaxial loading. Cyclic bilateral loading tests on fourteen 1/14-scale pier specimens with different slenderness ratios, axial load ratios, and transverse reinforcement ratios were carried out to investigate the damage propagation and the cumulative dissipated energy with displacement loads. By considering the influence of energy dissipation on structural damage, a new damage model (M-Usami model) was developed to assess the damage characteristics of hollow RC piers. The results present four consecutive damage stages during the loading process: (a) cracking on concrete surface, (b) yielding of longitudinal reinforcements; (c) spalling of concrete, and (d) collapsing of pier after the concrete crushed and the longitudinal bars ruptured due to the flexural failure. The damage level caused by the seismic waves can be reduced by designing specimens with a good seismic energy dissipation capacity. The theoretical damage index values calculated by the M-Usami model agreed well with the experimental observations. The developed M-Usami model can provide insights into the approaches to assessing the seismic damage of hollow RC piers subjected to bilateral seismic excitations.

scholarly journals Structural damage identification based on gray cloud rule generator algorithm

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401881990 ◽  
Author(s):  
Hui-Yong Guo ◽  
He-Fa Yuan ◽  
Qi Huang
Keyword(s):  
Energy Dissipation ◽  
Structural Damage ◽  
Strain Energy ◽  
Damage Identification ◽  
Cloud Model ◽  
Structure Model ◽  
Cloud Droplets ◽  
Modal Strain Energy ◽  
Energy Dissipation Ratio ◽  
Better Than

It is difficult for the traditional methods to identify uncertain damage problems caused by noise. Therefore, a gray cloud rule generator algorithm based on cloud model and modal strain energy is presented to solve the problems. Cloud model can simulate both randomness and fuzziness with fixed parameters. Therefore, it is applicable for the uncertain damage problems. First, modal strain energy and modal strain energy dissipation ratio index are introduced. Then, numerical characteristics of a cloud model are described and some cloud generators are analyzed. Finally, a gray cloud rule is proposed and the gray cloud rule generator algorithm based on the gray cloud rule generator and modal strain energy is developed. The interference of uncertain noise is reduced through a large number of cloud droplets. A two-dimensional truss structure model has been used to verify the effectiveness of the algorithm. The results indicate that the proposed gray cloud rule generator algorithm is applicable to identify the uncertain damage caused by noise, and the identification results of the proposed method are relatively better than those of modal strain energy dissipation ratio index.

Structural Multi-Damage Identification Based on Modal Strain Energy Equivalence Index Method

2014 ◽  
Vol 14 (07) ◽  
pp. 1450028 ◽  
Author(s):  
Hui Yong Guo ◽  
Zheng Liang Li
Keyword(s):  
Energy Dissipation ◽  
Structural Damage ◽  
Strain Energy ◽  
Damage Identification ◽  
Index Method ◽  
Modal Strain Energy ◽  
Energy Equivalence ◽  
Before And After ◽  
Accurate Expression ◽  
Equivalence Theory

In order to solve structural multi-damage identification problems, a damage detection method based on modal strain energy equivalence index (MSEEI) is presented. First, an accurate expression of modal strain energy (MSE) before and after damage occurs is given. Then, according to the energy equivalence theory that the change in MSE caused by the damage should be equivalent to the energy dissipation caused by the same damage, an energy equivalence equation is deduced. Finally, four roots of the energy equivalence equation are found and a MSEEI is obtained from the four roots. Simulation results demonstrate that the proposed MSEEI method can identify structural damage locations and extent with good accuracy. Identification precision of the proposed method is clearly better than that of the modal strain energy dissipation ratio index (MSEDRI) method.

Seismic Analysis and Design of RC Frame With New Metallic Dampers

2006 ◽  
Author(s):  
Hong-Nan Li ◽  
Gang Li
Keyword(s):  
Energy Dissipation ◽  
Structural Damage ◽  
Seismic Analysis ◽  
Traditional Approach ◽  
Seismic Energy ◽  
Analysis And Design ◽  
Good Ability ◽  
Metallic Dampers ◽  
Energy Dissipated ◽  
Metallic Damper

Earthquake can make structures damaged and crumble. The traditional approach to seismic design has been based upon providing a combination of strength and ductility to resist the imposed loads. Thus, the level of the structure security cannot be achieved, because the disadvantage of the designing method is lack of adjusting capability subjected to an uncertain earthquake. The presence of some damping (energy dissipation) in buildings has been recognized and studied by professional researchers. Passive energy-dissipated system, as a category of vibration control methods, lead the inputting energy from earthquake to special element, thereby reducing energy-dissipating demand on primary structural members and minimizing possible structural damage. In this paper, a new idea of designing metallic damper is presented and realized through the improved dampers that are of a certain bearing forces in plane of plate and suitable energy-dissipating capability by making metallic dampers in different shapes. New types of metallic dampers are called as “dual functions” metallic damper (DFMD), because it not only provides certain stiffness in normal use for a building, but also are of good ability of the seismic energy-dissipation. The structural configuration and mechanical characteristics of the models and prototypes of the DFMDs are analyzed and experimented so as to verify the seismic performance of the dampers. Finally, the DFMDs applied to a new building in China are introduced and numerical results demonstrate the effectiveness of the DFMD.

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