Showing papers on "Damper published in 2022"

An experimental and numerical study of brace-type long double C-section steel slit dampers

Abstract: Abstract In this research study, a novel double C-section steel slit damper (DCSSD) was proposed. Six cyclic loading tests of DCSSD specimens were carried out to study the effects of strip aspect ratio, thickness of flange, damper length and steel grades on the hysteretic behaviour and resistance of the DCSSD. Test results showed that the proposed DCSSD exhibited good structural performance in terms of initial stiffness, resistance, ductility and energy dissipation capability. The equivalent damping ratio of all DCSSD specimens exceeded 0.45 while that of the DCSSD using Q160 was over 0.50. Moreover, the cumulative displacement of the DCSSD using Q160 could approach 1500 mm. Subsequently, numerical models of test specimens were built to further investigate load transfer mechanism of the DCSSD. Good agreement was observed between the numerical simulations and the test results. The distribution of the moment and shear over the strips were extracted from the FE database, and the effectiveness of the long DCSSD was confirmed by the even moment and shear distribution profile. Finally, the accuracy of the available design equations of slit steel damper (SSD) documented in the literatures for predicting the initial stiffness and resistance of DCSSD was evaluated. In general, the design models produced inconsistent predictions of the initial stiffness of the test specimens. The existing design equations for predicting the ultimate strength of the DCSSDs were relatively conservative. • A novel brace-type long double C-section steel slit damper (DCSSD) was proposed and experimentally investigated. • Numerical study was conducted to enable further understanding of the test specimens. • The applicability of the current design models for steel slit dampers in predicting critical design parameters (e.g. stiffness and resistance) of the long DCSSDs was examined and discussed.

Seismic performance and material-level damage evolution of retrofitted RC framed structures by high-performance AVED under different shear-span ratio

Abstract: To upgrade the seismic performance of reinforced concrete framed structures with insufficient seismic capability, the high-performance acrylate viscoelastic dampers (AVED) are developed. A series of dynamic mechanical performance tests are carried out on high-performance AVED. A new strategy for retrofitting RC framed structures using AVED is proposed. To systematically study this new retrofitting structural system, the seismic performance of seven RC frame specimens and seven AVED-added RC frame specimens with different shear-span ratios of 2.0–8.0 are compared. On this basis, the influence rule of shear-span ratio on structural damage evolution is qualitatively analyzed. The structural damage evolution at material-level under different shear-span ratios is qualitatively comparted and analyzed in the whole process. The research results show that the self-developed AVED has excellent energy-consumption capability, and dynamic mechanical properties and energy-consumption capability are strongly dependent on frequency and displacement amplitude. The added AVED greatly improves the seismic performance of the retrofitted RC frame structure. At the same time, AVED effectively improves the failure mode of the structure and avoids the brittle failure mode of the beam-column joints under low shear-span ratios.

Machine learning-driven performance-based seismic design of hybrid self-centering braced frames with SMA braces and viscous dampers

Abstract: Abstract A hybrid self-centering braced frame equipped with shape memory alloy-based self-centering braces (SMA-SCBs) and viscous dampers is proposed to achieve enhanced seismic performance. Based on the proposed hybrid strategy combining the contributions of SMA-SCBs and viscous dampers, this paper investigates the advantages of such hybrid self-centering braced frames in achieving the desired maximum inter-story drift under a considered seismic intensity. To this end, the influence of design parameters of SMA-SCBs and viscous dampers on hybrid self-centering braced frames is examined through parametric dynamic analyses of equivalent single-degree-of-freedom systems. The analysis results indicate that the post-yield stiffness ratio α and energy dissipation factor β of SMA-SCB, and the contribution of viscous damper show significant influence on the peak displacement responses of hybrid self-centering braced frames. The constant inelastic displacement ratio prediction model for hybrid self-centering braced frames is developed using machine learning algorithms. A performance-based seismic design method is subsequently proposed for the hybrid self-centering braced frames to achieve the target displacement responses based on the developed machine learning models. Two hybrid self-centering braced frames are designed based on the proposed design method. Nonlinear dynamic analyses are conducted to investigate the seismic performance of the designed structures. To highlight the advantages of the hybrid self-centering braced frames, another six-story self-centering braced frame with SMA-SCBs only is also studied in this paper. The analysis results indicate that all the designed hybrid self-centering braced frames can achieve the desired performance objective. Compared to the self-centering braced frame with SMA-SCBs only, the hybrid self-centering braced frames can achieve much smaller base shear demand and absolute floor acceleration responses.

Optimal design and performance assessment of multiple tuned mass damper inerters to mitigate seismic pounding of adjacent buildings

Abstract: This work investigates the efficiency of tuned inerter dampers (TIDs) in controlling seismic response of two adjacent buildings and the pounding distance between them. Pervious research on this subject has shown that installing TIDs in every floor of one of the buildings and coupling each floor of the two buildings with additional inerters (CS1) provides the best control performance. Some potential drawbacks of this solution are the large number of control devices used and practical difficulties associated with sharing inerters between adjacent buildings. To overcome these drawbacks, we propose a new configuration of TMDIs, called here as CS2. The proposed configuration makes use of much fewer control devices than CS1 and does not require coupling between the two buildings. Contrary to the findings of the published literature, we show that uncoupled control systems can be configured and tuned to be more effective than coupled systems. This superior performance of the proposed system is primarily due to the different arrangement of inerter devices in CS2 compared to that in CS1. In CS2, the inerters are connected to TMD masses rather than to the adjacent floors as is done in CS1. Performance assessment of the proposed solution and its comparison with CS1 is carried out through two numerical examples and several ground motions covering a large range of amplitude and frequency content. In the first numerical example, the adjacent buildings are of different heights but similar fundamental periods of vibration. In the second one, the buildings are of the same height but different fundamental periods of vibrations. These two examples cover cases of adjacent buildings facing lower and higher risk of pounding, respectively. The proposed solution is found to be effective and better than existing TID configuration in both the numerical examples studied here. • The proposed solution makes use of much fewer control devices and does not require coupling between the two buildings. • Contrary to the findings of literature, the proposed uncoupled control systems can be more effective than coupled systems. • Assessment is conducted for two numerical examples subjected to ground motions covering a large-range of frequency content.

A review on various configurations of the passive tuned liquid damper

Abstract: Passive tuned liquid dampers, being cost-effective, easy to implement, and reliable structural vibration control devices, have received significant attention from designers and researchers. Considerable works devoted to the extraction of higher damping, increase in volumetric efficiency, improvement in architectural adaptability, and use in a large spectrum of structures have led to the development of a variety of configurations of passive tuned liquid dampers. Rigorous research efforts are being devoted to the utilization of different forms of tuned liquid dampers for the vibration control of buildings, bridges, chimneys, wind turbines, etc. However, till now, only a few varieties of tuned liquid dampers have been implemented in real-life structures, while the others require further refinement. This necessitates the present work, through which a systematic review on tuned liquid dampers of various configurations for structural response reduction is presented, with a focus on the design of the dampers. To organize the review in a structured manner, the large family of tuned liquid dampers is categorized into five groups based on their energy dissipation mechanism, namely the tuned sloshing damper, tuned liquid column damper, combined tuned sloshing damper-tuned liquid column damper system, compliant liquid damper, and liquid damper with submerged tuned oscillator. The modeling, analysis, design, and performance-related aspects of the different varieties of tuned liquid dampers are covered. The advantages and applicability of the different types of tuned liquid dampers are highlighted along with their real-life installations. The current gaps in the development of the various tuned liquid damper configurations and scope of future developments are also identified.

Predictive Model of Dynamic Mechanical Properties of VE Damper Based on Acrylic Rubber–Graphene Oxide Composites Considering Aging Damage

Abstract: AbstractBecause shock absorbers are an important component of high-rise buildings, it is essential to be able to detect damage to them. Viscoelastic (VE) dampers, as a common shock absorber, direct...