Seismic response control of benchmark highway bridge using passive hybrid control systems

In this study, the seismic response of a benchmark highway bridge is investigated with passive hybrid systems consisting of high damping rubber bearing (HDRB) and linear and nonlinear viscous fluid damper (VFD). The Phase I problem of the benchmark highway bridge is considered for this study. The ground acceleration is applied at all supports of the bridge. A comparative study is performed among the passive control strategies for seismic response control of the highway bridge by calculating various evaluation criteria as mentioned in the benchmark highway bridge problem. A parametric study has been conducted to find different parameters of VFD and HDRB. The optimum damping coefficient and velocity exponent are found for VFD and optimum isolation time period and optimum damping ratio are found for HDRB. The passive hybrid control system consisting of HDRB and nonlinear VFD gives better performance for reduction of base shear, overturning moment, displacement at midspan, bearing deformation and displacement at abutment of the bridge. Hence, it can be deduced that the performance of passive hybrid control system consisting of HDRB and nonlinear VFD is better than individual VFD and HDRB control systems.

Earthquake response of benchmark cable-stayed bridge with passive hybrid control systems is investigated. The passive hybrid system consists of high damping rubber bearing, lead-rubber bearing, friction pendulum system and resilient-friction base isolator (R-FBI) supplemented with the linear and non-linear viscous fluid damper (VFD). Considering the phase-I benchmark problem, the ground acceleration is only applied in the longitudinal direction acting simultaneously at all supports. The seismic response of benchmark bridge is obtained by solving the governing equations of motion by Newmark's step-by-step integration method. A comparative performance study among the four hybrid control systems for seismic response control of bridge is carried out by finding the various evaluation criteria under different parameters of the hybrid control system. Significant reductions in the base shear, overturning moment and other responses (especially deck displacements) were observed by using the passive hybrid control s...

The present paper deals with the optimum performance of the passive hybrid control system for the benchmark highway bridge under the six earthquakes ground motion. The investigation is carried out on a simplified finite element model of the 91/5 highway overcrossing located in Southern California. A viscous fluid damper (known as VFD) or non-linear fluid viscous spring damper has been used as a passive supplement device associated with polynomial friction pendulum isolator (known as PFPI) to form a passive hybrid control system. A parametric study is considered to find out the optimum parameters of the PFPI system for the optimal response of the bridge. The effect of the velocity exponent of the VFD and non-linear FV spring damper on the response of the bridge is carried out by considering different values of velocity exponent. Further, the influences of damping coefficient and vibration period of the dampers are also examined on the response of the bridge. To study the effectiveness of the passive hybrid system on the response of the isolated bridge, it is compared with the corresponding PFPI isolated bridges. The investigation showed that passive supplement damper such as VFD or non-linear FV spring damper associated with PFPI system is significantly reducing the seismic response of the benchmark highway bridge. Further, it is also observed that non-linear FV spring damper hybrid system is a more promising strategy in reducing the response of the bridge compared to the VFD associated hybrid system.

This paper presents a numerical study on the seismic damages and failure modes of a trial designed cable-stayed bridge (CSB) with a central span of 1,400 m under earthquake excitations. A passive hybrid control system is proposed to mitigate the seismic damage and improve the failure mode of the CSB; this is composed of a passive control system and several supplemental nonstructural links used as sacrificial energy dissipation devices. The passive control system, including conventional viscous fluid dampers (VFDs), is presented for comparison with the hybrid system. The results show that the top and bottom regions of the tower are simultaneously subjected to severe damage under extreme ground motion, indicating that the tower experiences an unexpected failure mode with double plastic hinges, whereas the piers experience a typical flexural failure mode, with only one plastic hinge concentrated at the bottom region of the pier in the transverse direction. The effects of the proposed passive hybrid control system on seismic damage control are superior to those of the passive control system with VFDs. As a result, the passive hybrid control strategy can successfully control seismic damage and effectively improve the failure mode of the CSB so that its seismic performance meets damage control targets based on seismic damage criteria.

Bridge collapse events are common in major earthquakes around the world, among which continuous girder bridges are the most involved. In order to explore the collapse mechanism of a continuous girder bridge in an earthquake, the collapse mode of a two-span continuous girder bridge specimen which had been studied by the shaking table test was analyzed. Then, on the basis of the conventional plate rubber bearing system, the collapse control strategies which were high damping rubber bearing, fluid viscous damper, lock-up clutch control methods were discussed. It is found that high damping rubber bearing can delay the collapse time but the collapse mode remains the same; lock-up clutch has the best displacement control effect for the superstructure, but its energy consumption performance is not as good as that of a fluid viscous damper; high damping rubber bearing is quite suitable for protecting the substructure under short-period ground motion to avoid the bridge collapse caused by the failure of piers; fluid viscous damper and lock-up clutch are suitable for protecting the superstructure under long ground seismic motion to avoid the bridge non-use resulted from girder lowering; three collapse control methods can improve the anti-collapse ability of the bridge specimen, although no matter which control method is used, the bridge specimen may still collapse under strong earthquakes, but the target of postponing collapse time can be realized by means of various effective control methods.

The prediction of the magnitude and impact of forthcoming earthquakes remains an elusive challenge in the field of science. Consequently, extensive research efforts have been directed toward the development of earthquake-resistant design strategies aimed at mitigating building vibrations. This study focuses on the efficacy of fluid viscous dampers (FVDs) in augmenting the seismic response of a low-rise residential reinforced-concrete building, which is base-isolated, using high–damping rubber bearings (HDRBs). The structural analysis employs a non-linear approach, employing ETABS v16 software for building modeling and conducting non-linear dynamic analysis using artificial accelerograms specific to Algeria. Three distinct connection configurations to the building’s base are investigated: (1) a fixed-base structure; (2) a structure isolated by HDRBs; and (3) a structure isolated utilizing a novel parallel arrangement of HDRBs in conjunction with FVDs. Comparative evaluation of these configurations reveals noteworthy findings; the results demonstrate that the base isolation system, comprising HDRBs and FVDs, significantly diminishes the base shear force by over 80% and reduces acceleration by 54% while concurrently increasing displacement by 47%. These findings underscore the effectiveness of incorporating FVDs in conjunction with HDRBs as a means to enhance the seismic response of reinforced concrete buildings. This study showcases the potential of such structural analyses to contribute to the development of earthquake-resistant design approaches, providing valuable insights for architects and engineers involved in constructing resilient buildings in seismically active regions.

Passive hybrid systems for earthquake protection of cable-stayed bridge

The performance of passive control system for the seismic protection of a multi-tower cable-stayed bridge with the application of partially longitudinal constraint system is investigated. The seismic responses of the Jiashao Bridge, a six-tower cable-stayed bridge using the partially longitudinal constraint system are studied under real earthquake ground motions. The effects of the passive control devices including the viscous fluid dampers and elastic cables on the seismic responses of the bridge are examined by taking different values of parameters of the devices. Further, the optimization design principle of passive control system using viscous fluid dampers is presented to determine the optimized parameters of the viscous fluid dampers. The results of the investigations show that the control objective of the multi-tower cable-stayed bridge with the partially longitudinal constraint system is to reduce the base shears and moments of bridge towers longitudinally restricted with the bridge deck. The viscous fluid dampers are found to be more effective than elastic cables in controlling the seismic responses. The optimized parameters for the viscous fluid dampers are determined following the principle that the peak displacement at the end of bridge deck reaches to the maximum value, which can yield maximum reductions in the base shears and moments of bridge towers longitudinally restricted with the bridge deck, with slight increases in the base shears and moments of bridge towers longitudinally unrestricted with the bridge deck.

Several earthquakes have shown that concrete continuous bridges suffer from major damage and permanent deformations. This paper investigates the use of high damping rubber (HDR) bearings to improve seismic performance of concrete continuous bridge. The shaking table array test of a two-span isolated continuous bridge specimen with 1:3 scale was carried out to study the seismic response characteristics of the continuous bridge with HDR bearing isolation. The experimental results were compared with the seismic response of non-isolated continuous girder bridge specimen. The results indicated that the seismic response of continuous girder bridge varied with input ground motion, direction and PGA. In terms of HDR bearing isolation system, there was time lag between seismic responses of the upper and lower structures, and the acceleration of the side pier was larger than that of the middle pier while displacement response has better symmetry than non-isolated specimen. The effect of vibration isolation varied with shaking frequency, intensity and direction. The seismic damage was mainly concentrated in the bottom of the middle pier column and the middle bearing. The horizontal shear capability model of the HDR bearing is proposed as the bilinear restoring force model. The numerical analysis model of the bridge specimen established on the simplified bearing model can reflect the damping effect of the HDR bearing on the concrete continuous bridge.

A fractional derivative model to include effect of ambient temperature on HDR bearings

An optimum retrofit strategy for moment resisting frames with nonlinear viscous dampers for seismic applications

Being the critical hydraulic structure in the construction of national water diversion projects, the large-scale aqueduct is one of the indispensable buildings in the rational allocation of water resources. Moreover, its safe operation during an earthquake is related to the success of the national water network’s construction. In this paper, HDRBs (high damping rubber bearings) have been used as the seismic isolation device for the large aqueduct, considering the FSI (fluid solid interaction) between the water and the walls of the aqueduct, and the mechanical model of HDRBs has been constructed by the bilinear model. The dynamic responses of the large aqueduct under different ground motion excitations, including different peak ground accelerations (PGAs) and operating conditions, have been calculated using the precise integration method. At the same time, the influence of RB (rubber bearings) and HDRBs, two kinds of bearings, on the seismic response of the large aqueduct is compared and analyzed. The maximum reduction in natural frequency with HRDB is about 72%, compared with the use of RB under different working conditions. When there is substitution of HDRB for RB, the stresses in the concrete at the corresponding positions decrease from 1.87 MPa to about 0.71 MPa. The analysis shows that HDRBs are equipped with well seismic isolation and energy dissipation performance, which can effectively reduce the seismic responses and improve the seismic performance of the large aqueduct. In addition, it shows that HDRBs have well adaptability to different operating conditions, ground motion excitation, and PGA, which can be extended to the constructions of aqueduct projects with high seismic intensity and complex geological conditions.

The motion equation of a one-degree-of-freedom system when subjected to earthquakes is usually not solved by analytic methods. This problem can only be solved through the time step method, when integrating differential equations. This paper is devoted to presenting a numerical solution for a seismic analysis problem of a highway bridge pier with high damping rubber bearings under earthquakes. Based on time-stepping Newmark’s method, a numerical solution is developed to predict the seismic responses of the piers. The iteration Newton-Raphson method is also applied in the problem for static analysis of this nonlinear system. The ground acceleration in the analysis is the type- II earthquake in JRA 2004 (Japan Road Association). Further-more, high damping rubber bearings are modeled by the two models: the bilinear design model and the rheology model proposed by authors. After that, the stress responses and the displacement responses of the pier are obtained by a program that is implemented in Matlab software. The comparison results obtained from the two models show that the seismic responses of the pier strongly depend on the modeling of the rubber bearings. This is the important note for engineers to design the earthquake resistance of bridges with high damping rubber bearings. The solution is also a useful tool for engineers to predict the seismic responses of bridge piers in the design procedure.

In this study, a multi-degree-of-freedom numerical model is created to represent the elastic behavior of a typical Chilean two-family, low-cost, confined masonry house. Ambient vibration testing was performed to determine the fundamental natural frequencies of the structure in the longitudinal and transverse directions through a non-parametric system identification technique. Based on the ambient vibration data, an estimation of equivalent viscous damping of the structure is made using the bandwidth method. The stiffness values are estimated using the natural frequencies measured from the ambient vibration testing. A number of passive isolation devices are considered as potential isolation systems for the structure. Each device is numerically modeled using fuzzy logic. The fuzzy models are created using experimental and analytical data to predict the force exerted on the structure by the device. The passive isolation systems considered include friction pendulum systems, high-damping rubber bearings, and two hybrid systems involving use of high-damping rubber bearings and shape memory alloy wire. Seismic performance of the structure in the longitudinal direction, augmented with each of the isolation systems mentioned above is compared with the performance of the traditionally-constructed structure using several performance indices.

In this paper, the capabilities of passive control of structures using hydraulic fluid dampers are compared to those of semi-active control. It is demonstrated that, in most cases, the performance achieved by a properly designed passive control system can be comparable to that of semi-active systems that use the state-of-the-art control algorithms. It is also shown that the optimum damping coefficients for passive control may be much smaller than the maximum values considered in semi-active control. These conclusions are supported by numerical simulations of several structures, including a case of actual implementation of semi-active control in a building structure. Copyright © 2006 John Wiley & Sons, Ltd.