Ping Tan

A Smart Base-Isolation Using Piezoelectric Friction Damper

A smart base-isolation system, composed of low damping bearings and piezoelectric friction damper is studied in this paper. The semi-active piezoelectric friction damper (PFD[1]) is proposed for control of peak dynamic response of seismic-excited structures. In the proposed PFD device, the friction force between two sliding plates is regulated by controlling the normal force using piezoelectricity across the damper, and its advantage is that its operation requires only minimal external power. A high efficient control algorithm is proposed for the semi-active control of the friction damper using a simple static output. The effectiveness of the PFD device and the control strategy in reducing the peak dynamic response of structures is investigated through an application to a 5-story base-isolated building. Numerical results demonstrate that the proposed PFD device and the control strategy are effective in reducing the peak drift of rubber-bearings of the base-isolated building subject to earthquakes.

A novel energy dissipation outrigger system with rotational inertia damper

Rotational inertia damper, a novel damper, possessing the advantage of displacement amplification, has been employed in outrigger system for seismic mitigation. The equivalent analysis model composed by a uniform cantilever beam and an equivalent spring was proposed to simulate the rotational inertia damper outrigger system, by which the corresponding dynamic characteristic equation was derived based on numerical assembly technique. To gain the response of the damped system, finite element method and state space method have been utilized. Finally, the results show that the pseudo-undamped natural frequency ratios and system modal damping ratios are significantly influenced by stiffness parameter of the exterior column, while the mass parameter of the rotational inertia damper has little effect on them. The optimal damping ratio can be acquired for one mode, but it may be worse for the other mode in the same position equipping rotational inertia damper. Furthermore, numerical simulation results for the typical earthquake records have verified that the rotational inertia damper outrigger has excellent control performance in displacement as well as acceleration. A good agreement between damping force and equivalent force also suggests that the damping force of rotational inertia damper is predominant and the inertial force has no significant effect on the structure.

Seismic Vulnerability Analysis of FRP Retrofitting Industrial Buildings

This study focus on derivation of such vulnerability curves using Fiber Reinforced Polymers technologies retrofitted conventional RC industrial frames with masonry infill wall. A set of stochastic earthquake waves which compatible with the response spectrum of China seismic code are created. Dynamic time history analysis is used to compute the random sample of structures. Stochastic damage scatter diagrams based different seismic intensity index are obtained. Seismic vulnerability of FRP-reinforced RC industrial frames is lower than unreinforced frames obviously, and seismic capability of frames using FRP technologies is enhanced especially under major earthquake.

Study on the Effect of Modified Differential Restoring Force Model on Seismic Response of Isolation Structure

Based on the compression-shear tests of different specifications LRBs (diameter 700mm,1000mm,1100mm) and shear strain correlation formula, the modified differential restoring force model (modified Bouc-Wen model) is suggested to simulate LRB. An isolated model, nine-story superstructure, is used as the numerical example. Using the unmodified and the modified differential restoring force model of the LRB, the differences of the seismic response of isolated structure are studied by numerical analysis and comparison. Result shows that, unmodified differential restoring force model commonly used in isolation design, except for acceleration response, other earthquake response has not significant error.

Shaking Table Test Study on Mid-Story Isolation Structures with Viscous Damper

Mid-story isolation structure is developing from base isolation structures. As a complex structural system, the work mechanism of base isolation structure is not entirely appropriate for mid-story isolation structure, and the prolonging of structural natural period may not be able to decrease the seismic response of substructure and superstructure simultaneously. In this paper, for a four-story steel frame model, whose prototype first natural period is about 1s without seismic isolation design, the seismic responses and isolation effectiveness of mid-story isolation system with linear natural rubber bearing and viscous damper are studied experimentally by changing the location of isolation layer. Respectively, the locations of isolation layer are set at bottom of the first story, top of the first story, top of the second story and top of the third story. The results show that mid-story isolation can reduce seismic response in general, and substructure acceleration may be amplified.

Shaking Table Test Study on Mid-Story Isolation Structures

Mid-story isolation structure is developing from base isolation structures. As a complex structural system, the work mechanism of base isolation structure is not entirely appropriate for mid-story isolation structure, and the prolonging of structural natural period may not be able to decrease the seismic response of substructure and superstructure simultaneously. In this paper, for a four-story steel frame model, whose prototype first natural period is about 1s without seismic isolation design, the seismic responses and isolation effectiveness of mid-story isolation system with lead rubber bearing are studied experimentally by changing the location of isolation layer. Respectively, the locations of isolation layer are set at bottom of the first story, top of the first story, top of the second story and top of the third story. The results show that mid-story isolation can reduce seismic response in general, and substructure acceleration may be amplified.

Seismic Vulnerability Analysis of Reinforced Concrete Frames with Mild Steel Dampers

This study focus on derivation of such fragility curves using conventional old reinforced concrete (RC) frames with Mild Steel Damper (MSD) of flexural energy dissipation braces. A set of stochastic earthquake waves compatible with the response spectrum of China seismic code selected to represent the variability in ground motion. Dynamic inelastic time history analysis was used to analyze the random sample of structures. Weak position was be pointed out, The result reveal that excellent reduction effect for structure of MSD is favorable and obvious under major earthquake.

Study on a Simple Self-Resetting Sliding Isolation

This paper presents a simple Self-resetting sliding isolation system, which is composed of graphite sliding device and simple rubber bearing. Theoretical analysis is carried out. Shaking table test for a typical brick masonry structure in village of China is performed on a 1:4 scale. Results show that the proposed new isolation system can achieve a favorable level of performance.

Vibration Control of Serially Connected Isolation System Using Piezoelectric Actuator

This paper presents a bidirectional piezoelectric actuator, which can be used to vibration control of serially connected isolation System. Firstly, the performance test of this control device was processed. Then vibration control experiment of serially connected isolation system with this control device based on sweep sine shaking table was carried out. The experimental results show that this control device has stable mechanical properties, produces semi-active control force fast and has the outstanding control efficiency for serially connected isolation system. In addition, this control still has the satisfactory control efficiency when the piezoelectric actuator of this control is failed, which indicates the fail-safe function of this control.

Stochastic Vibration-Based Fragility Analysis of Middle-Story RC Frames

A lot of reinforced concrete (RC) frames have being collapsed during Si Chuan Earthquake (SCE) in western China May 12th.2008, at the same time others have being injured on several levers. In recent years how to evaluate reliability and fragility of the buildings and search reasonable design practice of seismic strengthening of these buildings is urgent mission. One goal of fragility analysis is set up relation between vulnerability and seismic intensity. A set of stochastic earthquake waves compatible with the response spectrum of China seismic code selected to represent the variability in ground motion. Dynamic inelastic time history analysis was used to analyze the random sample of structures. In the end structural weak position also be pointed as valuable consultation for diagnose these buildings and fragility curves of typical middle-storey RC frames of China was obtained finally.