Seismic Fragility and Life Cycle Cost Analysis of Reinforced Concrete Structures with a Hybrid Damper

The main objective of this research is to develop a hybrid damper by combining the friction damper (FD) and the X-shaped metallic damper (XMD) to enhance the performance of a building under seismic excitations with different peak ground accelerations (PGA). Four- and twelve-storey-reinforced concrete buildings were retrofitted with the hybrid damper, and seismic fragility, nonlinear dynamic, and life cycle cost analyses were executed on both structures to evaluate the performance of the hybrid damper and are compared with the FD and XMD of same yield load. According to the nonlinear dynamic analysis results, when a four-storey structure is installed with the XMD, FD, and hybrid dampers, the percentage of deduction of the average of the maximum interstorey drifts is 63, 67, and 74, respectively. When a twelve-storey structure is installed with the XMD, FD, and hybrid dampers, the percentage of deduction of the average of the maximum interstorey drifts is 59, 64, and 71, respectively. So the performance of the hybrid damper is superior to the XMD and FD in reducing interstorey drift of both structures. Results also show that the hybrid damper has enhanced the energy dissipation capacity compared to the XMD and FD under earthquakes with both low and high PGA values. According to fragility analysis results, the performance of the hybrid damper is superior to the XMD and FD in reducing the probability of attaining the collapse state. Life cycle cost analysis results show that structures with the hybrid damper acquired the shortest repair time and lowest repair cost.

Experimental and numerical investigation of damping in a hybrid automotive damper combining viscous and multiple-impact mechanisms

One of the least investigated approaches in passive vibration control is the possibility of combining different types of dampers that use different damping principles. Such a combination process, if wisely designed and implemented, has the potential to increase the damping performance and extend the damper’s application. The primary purpose of this work is to experimentally and numerically investigate the damping behavior of a novel Fluid-Impact Hybrid Damper. This damper combines a conventional Viscous Fluid Damper with a Particle-Impact Damper. The Fluid-Impact Hybrid Damper comprises a 3D-printed plastic box attached to the Viscous Fluid Damper’s moving rod and filled with stainless steel balls. An experimental setup was designed to drive the Viscous Fluid Damper’s rod into harmonic oscillations at different frequencies (1, 2, 4, 6, and 8 Hz). The number of balls was changed three times (5, 10, and 15) to assess the effect of this parameter on the damping performance of the Fluid-Impact Hybrid Damper. A finite element model of the Fluid-Impact Hybrid Damper was developed using LS-Dyna explicit simulation program. The objective of the FE model is to investigate the elastoplastic balls-box collisions using a piecewise-linear plasticity material model. For both the experimental and numerical results, the Frequency Response Function was considered as the main comparison component for a set of force-independent results. The measured Frequency Response Functions showed a noticeable reduction in amplitude at the system’s natural frequency (2 Hz), with an acceptable accuracy between the two approaches.

Optimal Seismic Design of Stiffness and Gap of Hysteretic-Viscous Hybrid Damper System in Nonlinear Building Frames for Simultaneous Reduction of Interstory Drift and Acceleration

The viscous-hysteretic hybrid (HVH) damper system recently introduced by one of the authors has a clear property that, when the hysteretic dampers with gap mechanism become active (stiffness element starts working), the acceleration of building frames with this damper system as a stopper attains large values in spite of the advantageous feature to prevent excessive deformation. It is therefore desired that both the maximum interstory drift and the maximum acceleration exhibit an acceptable value with appropriate compromise. The double impulse as a simplified version of one-cycle sine wave as a representative of the main part of near-fault ground motions can simulate the maximum interstory drifts properly. However, it cannot simulate the maximum accelerations due to its impulsive nature. In this case, the sine wave corresponding to the double impulse can play an important role in the reliable simulation of the maximum accelerations. Even in such circumstance, the analysis using the double impulse is important because it enables to obtain the critical timing of the input, i.e. the nonlinear resonant frequency of the sine wave without repetition. The investigations on the criticality of the sine wave corresponding to the critical double impulse show that the critical timing of the double impulse leads to the nonlinear resonant frequency of the sine wave in view of the maximum interstory drift, the maximum top acceleration and the maximum relative acceleration for the constant input acceleration and the constant input velocity except for some cases. It is demonstrated finally that the index in terms of the maximum interstory drift and the maximum acceleration can be introduced as an appropriate parameter for deriving the optimally compromised gap quantity of hysteretic dampers with gap mechanism for various input velocity levels and various hysteretic damper stiffness ratios.

The Effect of slit-friction hybrid damper on the Performance of Dual System

Aims: The aim of the present paper is to evaluate the behavior of slit friction hybrid dampers (SFHD) on steel structures. Therefore, the behavior moment resisting steel frames of structures in original stats and structures equipped with hybrid damper with two different types of behavior was analyzed and evaluated. Background: The recent study evaluated the combined effect of shear-friction dampers and slit dampers with measurements of non-uniform strips in seismic protection for different levels of energy. The recent study was carried out a about hybrid dampers, consisting of friction and split dampers in response to small and large earthquakes. Previous results have shown the ability of inactive hybrid systems in improving the reaction of structures to traditional lateral-systems. Kim and Shin showed that structures consisted of hybrid dampers needed less repair cost and time. Methods: Pushover and time history were carried out on original structures and structures equipped with dampers, in 5 and 10 stories structures. Results: Analysis about the probability of collapse showed about 30% and 84%. Conclusion: According to the result, by adding the SFHD, increased stiffness by 17% in retrofitted structures such as drift and displacement of roof decreases by 27% and 20% in push over analysis, respectively. Also, displacement in time history analysis up to 55% reduces in average. Also, the results of the IDA show that adding the SFHD to structures significantly increases by 55% the spectral acceleration capacity in structures.