Seismic retrofit of precast soft-storey building using diagonal steel-shape memory alloy bracing device: Numerical investigation

2018 ◽  
Vol 22 (3) ◽  
pp. 802-817 ◽  
Author(s):  
Xiaoxian Liu ◽  
Hing-Ho Tsang ◽  
John L Wilson
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Tensile Force ◽  
Time History ◽  
Seismic Retrofitting ◽  
Nonlinear Time History Analysis ◽  
Building Frame ◽  
Soft Storey ◽  
Steel Shape ◽  
Storey Building

A diagonal steel-shape memory alloy bracing device is proposed for seismic retrofitting of vulnerable building frame structure. Superelastic shape memory alloy bar is put in series with steel bars in the bracing. The device makes use of the loading plateau of superelastic shape memory alloy to limit the tensile force of diagonal bracing. A precast soft-storey building frame in Australia was selected for a case study. A numerical model of the frame was developed and validated with the results from full-scale pull-down field tests. Nonlinear time history analysis was then conducted to evaluate the seismic performance of the frame with different retrofitting strategies. The result shows that the diagonal steel-shape memory alloy bracing can reduce the displacement demand on the soft-storey frame. Meanwhile, the level of tensile force of steel-shape memory alloy bracing can be controlled by the force plateau of the shape memory alloy bar, which is recommended to be 20% of the yielding force of the steel bar. The lower tensile force demand could alleviate the force demand at the associated support connections.

Mitigation of Vertical and Horizontal Seismic Excitations on Bridges Utilizing Shape Memory Alloy System

2013 ◽  
Vol 831 ◽  
pp. 90-94 ◽  
Author(s):  
H. Aryan ◽  
M. Ghassemieh
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Three Dimensional ◽  
Time History ◽  
Alloy System ◽  
Practical Method ◽  
Nonlinear Time History Analysis ◽  
Vertical Acceleration ◽  
Three Dimensional Model ◽  
Seismic Excitations

Vertical seismic excitation has a tremendous effect on bridges and many researchers have pointed out bridges damages occurred during the past significant earthquakes which were direct results of ignoring vertical acceleration of ground motions. Many studies have emphasized the importance of extending practical methods to reduce effects of vertical acceleration of earthquakes besides effects of horizontal accelerations; but no practical method has proposed up to now. In this article, an innovative shape memory alloy system is proposed for bridges that can simultaneously controls effects of vertical and horizontal seismic excitations on bridge and reduce them. To evaluate the effectiveness of the shape memory alloy system, a nonlinear time history analysis is conducted on a detailed three-dimensional model of a multi-span simply supported bridge using a representative ground motion. The results show that the proposed new system is very effective for reducing effects of vertical and horizontal seismic excitations on bridges.

scholarly journals Life-cycle cost evaluation of steel structures retrofitted with steel slit damper and shape memory alloy–based hybrid damper

2018 ◽  
Vol 22 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Mohamed NourEldin ◽  
Asad Naeem ◽  
Jinkoo Kim
Keyword(s):  
Life Cycle ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Life Cycle Cost ◽  
Time History ◽  
Steel Structures ◽  
Cost Evaluation ◽  
Nonlinear Time History Analysis ◽  
Analysis Model ◽  
Hybrid Damper

In this study, the seismic capacity of a hybrid damper, composed of a steel slit plate damper and two shape memory alloy bars, is investigated through fragility analysis and life-cycle cost evaluation of a steel frame retrofitted with the damper. The nonlinear time history analysis model frames show that the seismic responses of the frames equipped with hybrid damper are significantly lesser than the frames retrofitted with conventional slit dampers. The enhancement in the seismic performance of frames retrofitted with hybrid damper is because of extra stiffness, energy dissipation, and self-centering capability provided by the shape memory alloy bars. It is also observed that the life-cycle cost of the frames equipped with hybrid dampers is smallest compared with the life-cycle cost of the bare frames and the frames equipped with slit dampers, even though the initial cost is of the hybrid damper is higher than that of the conventional slit damper.

scholarly journals Recentering Shape Memory Alloy Passive Damper for Structural Vibration Control

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Hui Qian ◽  
Hongnan Li ◽  
Gangbing Song ◽  
Wei Guo
Keyword(s):  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Structural Control ◽  
Structural Response ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Structural Vibration ◽  
Seismic Protection ◽  
Building Structures

This paper presents a preliminary study on the evaluation of an innovative energy dissipation system with shape memory alloys (SMAs) for structural seismic protection. A recentering shape memory alloy damper (RSMAD), in which superelastic nitinol wires are utilized as energy dissipation components, is proposed. Improved constitutive equations based on Graesser and Cozzarelli model are proposed for superelastic nitinol wires used in the damper. Cyclic tensile-compressive tests on the damper with various prestrain under different loading frequencies and displacement amplitudes were conducted. The results show that the hysteretic behaviors of the damper can be modified to best fit the needs for passive structural control applications by adjusting the pretension of the nitinol wires, and the damper performance is not sensitive to frequencies greater than 0.5 Hz. To assess the effectiveness of the dampers for structural seismic protection, nonlinear time history analysis on a ten-story steel frame with and without the dampers subjected to representative earthquake ground motions was performed. The simulation results indicate that superelastic SMA dampers are effective in mitigating the structural response of building structures subjected to strong earthquakes.

Seismic analysis and evaluation of several recentering braced frame structures

2013 ◽  
Vol 228 (5) ◽  
pp. 781-798 ◽  
Author(s):  
Jong Wan Hu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Seismic Analysis ◽  
Time History ◽  
Frame Structures ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Economic Point ◽  
Conventional Steel ◽  
Steel Bracing

After earthquakes, residual inter-story drifts greater than 0.5% in buildings may indicate a complete loss of the structure from an economic point of view. Recently, research efforts have been extended to the utilization of superelastic shape memory alloy materials for the smart control systems that can automatically reduce the plastic deformation of the structure subjected to strong seismic loading. Superelastic shape memory alloys are unique metallic alloys that undergo substantial inelastic deformations and regain their original conditions when applied loads are removed, thus alleviating the problem of permanent deformation. The frame structures make the best use of such shape memory alloy’s recentering capability if the superelastic shape memory alloy segments used to replace the steel segments are installed at the part where large deformation is likely to occur. The primary focus of this study is on the seismic response of special steel concentrically braced frames and buckling-restrained braced frames, utilizing superelastic shape memory alloy braces. In order to examine the comparative residual inter-story drift response of both braced frames, 3- and 6-story buildings were designed in accordance with current code specifications, and then nonlinear time-history analyses for two seismic hazard levels were conducted on 2D analytical frame models. The braced frames with superelastic shape memory alloy bracing systems were also compared to those with conventional steel bracing systems. Overall, analysis results show that the superelastic shape memory alloy bracing systems are more effective in decreasing residual inter-story drifts than the conventional steel bracing systems.

scholarly journals Mitigation of Seismic Risks to Soft-Storey Structures Using Toggle-Brace-Damper Systems

2012 ◽  
Vol 238 ◽  
pp. 833-837 ◽  
Author(s):  
Ricky W.K. Chan ◽  
Zhe Fei Zhao
Keyword(s):  
Time History ◽  
Ground Level ◽  
Nonlinear Time History Analysis ◽  
Lateral Stiffness ◽  
Governing Equations ◽  
Magnification Factor ◽  
Soft Storey ◽  
History Analysis ◽  
Nonlinear Time History ◽  
Sudden Reduction

Soft-storey mechanism is characterized by a sudden reduction of lateral stiffness in one or more levels of a structure. Soft-storey is often observed in the ground level due to the absence of wall or cladding. With recent develop of energy dissipation systems, soft-storey mechanism can be corrected by addition of a damper-brace assembly. In particular, this paper investigates the effect of toggle-damper-brace systems on such situations. Governing equations including the magnification factor and lateral stiffness contributed by a toggle-damper-brace are formulated. It was found that a toggle-damper-brace system, if proportioned correctly, will significantly increase the travel in the damper and overall stiffness of structure can be enhanced. An illustrative example is presented using nonlinear time history analysis implemented on MATLAB.

scholarly journals Theoretical Study on Vibration Control of Symmetric Structure with Shape Memory Alloy (SMA)-Friction Damper

2014 ◽  
Vol 8 (1) ◽  
pp. 803-808
Author(s):  
Yunli Gao ◽  
Wenjie Ren
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Vibration Control ◽  
Time History ◽  
Response Analysis ◽  
Analysis Program ◽  
Friction Damper ◽  
Symmetric Structure ◽  
In Series ◽  
Dissipation Elements

The paper proposed an innovative shape memory alloy (SMA)-friction damper. The damper consisted of the superelastic SMA wire and the friction element in series. According to the working mechanism of the damper, the paper set up the mechanical model of the damper. Seismic elastic-plastic time history response analysis program and energy analysis program of the damped structure were designed. The numerical calculations of the vibration control of a threestory shear-type symmetric structure with the damper were carried out. The results indicated that the damper can decrease the displacement and the inter-story displacement of the structure effectively, but increase the acceleration of the structure comparing with uncontrolled structure. The SMA-friction damper can not only adjust the working status of the energy dissipation elements automatically according to the seismic responses of the structure, but also has some advantages as simple configuration and economical application.

SEISMIC PERFORMANCE EVALUATION OF PILOTI-TYPE BUILDINGS AFTER AN EARTHQUAKE

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Hye-min Shin ◽  
Kyung-jae Shin ◽  
Su-woong Lee ◽  
Dae-geun Kim ◽  
Min-ki Lee ◽  
...  
Keyword(s):  
Large Scale ◽  
Dynamic Test ◽  
Time History ◽  
Seismic Retrofitting ◽  
Nonlinear Time History Analysis ◽  
Reinforced Concrete Frame ◽  
Seismic Performance Evaluation ◽  
Concrete Frame ◽  
Recent Earthquakes ◽  
Nonlinear Time History

On November 15, 2017, the second strongest earthquake occurred in Korea, which was 5.4 in size on the Richter Scale. The duration of the earthquake was short, but the damage was serious. Two recent earthquakes have shown that our country is no longer safe from earthquakes. However, to date, Korean structures are showing a low earthquake resistance, and seismic retrofitting is necessary in preparation for a large-scale earthquake. In this study, reinforcing effect of steel slit damper was analyzed based on the dynamic test results of the previously studied reinforced concrete frame. After that, push over analysis and nonlinear time history analysis using OpenSees were selected for the residential piloti-type building as the target building. In the above Korean earthquake, the damage to the piloti-type building was conspicuous. Through analysis, the vulnerable part of the piloti-type building was identified and the seismic strengthening with the steel slit damper was carried out.

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