Seismic Evaluation and Retrofit of 230-kV Porcelain Transformer Bushings

2001 ◽  
Vol 17 (4) ◽  
pp. 597-616 ◽  
Author(s):  
Amir S. Gilani ◽  
Andrew S. Whittaker ◽  
Gregory L. Fenves
Keyword(s):  
Seismic Performance ◽  
Seismic Evaluation ◽  
General Electric ◽  
Oil Leakage ◽  
Earthquake Simulator ◽  
Rigid Frame ◽  
Moderate Earthquake ◽  
High Level

Static and earthquake-simulator testing of two 230-kV, 3000A, Type-U transformer bushings manufactured in the mid 1980s by the General Electric (GE) Company was undertaken to evaluate both the seismic performance of bushings known to be vulnerable to damage from moderate earthquake shaking, and the efficacy of simple retrofit details. Both bushings survived earthquake shaking compatible with the IEEE spectrum for High Level qualification when mounted on a rigid frame. When mounted on a flexible frame, one 230-kV bushing was unable to sustain the High Level qualification shaking without oil leakage and slip of the porcelain units. Two retrofit details utilizing two semicircular ring plates and epoxy filler were prepared by utility representatives with the objective of limiting slip of the UPPER-1 porcelain unit over the gasket connection. The second detail, Ring-2, permitted the 230-kV bushing to sustain substantially larger accelerations and displacements than those of the unretrofitted bushing and eliminated the permanent slip of the UPPER-1 porcelain unit over the gasket connection for extreme earthquake shaking.

Earthquake Performance of Porcelain Transformer Bushings

2004 ◽  
Vol 20 (1) ◽  
pp. 205-223 ◽  
Author(s):  
Andrew S. Whittaker ◽  
Gregory L. Fenves ◽  
Amir S. J. Gilani
Keyword(s):  
Leakage Current ◽  
Performance Level ◽  
Oil Leakage ◽  
Fundamental Frequencies ◽  
Earthquake Simulator ◽  
Earthquake Performance ◽  
Resonance Search ◽  
Substation Equipment ◽  
High Level

The earthquake performance of 196-kV, 230-kV, and 550-kV porcelain transformer bushings was studied by earthquake-simulator experimentation and analysis. The fundamental frequencies of the 196-kV, 230-kV, and 550-kV bushings were identified to be approximately 15 Hz, 18 Hz, and 8 Hz, respectively, using resonance-search testing on the simulator. The corresponding damping ratios were between 2 and 4 percent of critical. The 196-kV and 230-kV bushings survived severe earthquake shaking and were qualified to the High Level per the IEEE 693-1997 standard. The discrepancy between excellent behavior in the laboratory and poor behavior in the field of these types of bushings calls into question the procedures used for qualification of substation equipment. The 550-kV bushing survived shaking at the moderate performance level with limited damage and minor oil leakage. Current procedures for fragility testing of transformer bushings were evaluated and found to be neither appropriate nor conservative.

Seismic performance of viscoelastically damped structures at different ambient temperatures

2020 ◽  
pp. 107754632096693
Author(s):  
Jun Dai ◽  
Zhao-Dong Xu ◽  
Pan-Pan Gai ◽  
Xiao Yan
Keyword(s):  
Ambient Temperature ◽  
Temperature Effect ◽  
Seismic Performance ◽  
Structural Parameters ◽  
Damping Ratio ◽  
Historical Earthquakes ◽  
Seismic Evaluation ◽  
Viscoelastic Damper ◽  
Ambient Temperatures ◽  
Seismic Displacement

Experimental results show that mechanical behaviors of viscoelastic dampers are greatly affected by ambient temperature. Neglecting the ambient temperature effect will lead to an inaccurate seismic evaluation on viscoelastically damped structures. This study investigates the ambient temperature effect on the seismic performance of viscoelastically damped structures. An efficient algorithm is proposed to solve the seismic response of viscoelastically damped structures at different ambient temperatures based on the time–temperature correspondence. Numerical simulations of a ten-story viscoelastically damped steel frame under historical earthquakes are presented to illustrate the ambient temperature effect on the seismic performance. The results show that the natural frequency decreases with the increase in ambient temperature, whereas the damping ratio change with ambient temperature greatly depends on the viscoelastic damper properties. The seismic displacement reduction, in general, decreases with the increase in ambient temperature. The seismic acceleration reduction with ambient temperature is affected by the viscoelastic damper properties, structural parameters, and earthquakes together.

scholarly journals The use of approximate methods of seismic assessment of structures

2018 ◽  
Vol 188 ◽  
pp. 03010
Author(s):  
Maria Basdeki ◽  
Argyro Drakakaki ◽  
Charis Apostolopoulos
Keyword(s):  
Seismic Performance ◽  
Mechanical Performance ◽  
Corrosion Damage ◽  
Masonry Structures ◽  
Seismic Evaluation ◽  
Approximate Methods ◽  
Rc Structures ◽  
Existing Structures ◽  
Corrosion Factor ◽  
Masonry Tower

Greece is an earthquake prone area, which is also exposed to coastal environment. Most existing buildings present common characteristics, concerning quality of the materials and environmental conditions [1].The vulnerability of these structures is exteriorized under powerful seismic loads. This is because they were designed, according to older regulations, primarily to bear vertical loads and secondarily to bear horizontal loads, an indicative sign of the absence of anti-seismic design. Designing and evaluation of the seismic performance of existing structures is a really complex issue, because structural degradation phenomenon is related to both corrosion damage of steel reinforcement on RC structures and high vulnerability of masonry. Precisely, the inadequate seismic performance of masonry structures, which is recorded under intense earthquakes, is attributed to the characteristics of masonry and to the ageing phenomena of the materials. For the seismic inspection of masonry structures, both EC2 and OASP can be used [3], although there is often a great misunderstanding concerning the range of the maximum permissible interventions, the financial inability and modern perceptions of redesigning [2]. On the other hand, in the case of RC structures, there is no prediction –concerning the corrosion factor- included in the international regulations and standards. In the current study is presented an experimental procedure, concerning a RC column before and after corrosion. An estimation concerning the drop of its mechanical performance has taken place, indicating the importance of the corrosion factor. Additionally, an existing monumental masonry tower building, was subjected to seismic evaluation [4]. Both OASP and EC2 inspection methods were used. The results pointed out that, for medium–intensity earthquakes, both analytical and approximate methods are respectable and reliable.

Analysis of dam response for foundation fault rupture

2009 ◽  
Vol 42 (1) ◽  
pp. 9-17
Author(s):  
Lelio Mejia ◽  
Ethan Dawson
Keyword(s):  
Seismic Performance ◽  
Case History ◽  
Engineering Profession ◽  
Fault Rupture ◽  
Seismic Evaluation ◽  
Embankment Dams ◽  
The Past ◽  
Limited Experience

Considerable knowledge and experience has been developed over the past 40 years in the engineering profession regarding the seismic performance and analysis of dams for earthquake shaking. However, comparatively limited experience is available regarding the evaluation of dams for the effects of foundation fault rupture during earthquakes. This paper examines the factors to be considered in the evaluation of embankment dams for foundation faulting, and illustrates the analysis of dam response under foundation faulting by means of a case history, the seismic evaluation of Aviemore Dam.

Research on Deformation Index Limits of RC Shear Walls Based on Material Damage

2014 ◽  
Vol 507 ◽  
pp. 322-327
Author(s):  
Yong Le Qi ◽  
Xin Xian Zhou ◽  
Can Dong Xie
Keyword(s):  
Seismic Performance ◽  
Shear Walls ◽  
Shear Wall ◽  
Mathematical Statistic ◽  
Material Damage ◽  
Seismic Evaluation ◽  
Deformation Index ◽  
Wall Structures ◽  
Displacement Angle ◽  
Seismic Deformation

This paper divides the seismic performance of shear wall into five levels: integrity, slight damage, slight ~ moderate damage and serious damage which are defined based on material damage. And physical and mechanical description of shear walls in each performance level is given. The displacement angle is selected as the seismic performance index limit. The numerical analysis of 524 pieces of shear walls has been made to discuss the influence on seismic deformation index limits of component according to axial compression ratio, flexure shear ratio, the nominal shear stress level, the hoop characteristic value and the reinforcement ratio of longitudinal bars. With mathematical statistic method, the calculation formula for deformation index limits of components is obtained, which can be used as the basis in the performance-based seismic evaluation of shear wall structures.

Influence of Tie Beams of Pier on the Seismic Performance of a Continuous Rigid Frame Bridge with Twin-Legged Piers

2011 ◽  
Vol 368-373 ◽  
pp. 1105-1110
Author(s):  
Yun Jing Nie ◽  
Xu Yan ◽  
Tie Ying Li
Keyword(s):  
Seismic Response ◽  
Seismic Performance ◽  
Seismic Design ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Continuous Rigid Frame Bridge ◽  
Analytical Results ◽  
Rigid Frame ◽  
Rigid Frame Bridge

In this paper, the influence of tie beams for piers is investigated on the dynamic characteristics and the seismic performance of a continuous rigid frame bridge with twin-legged piers. Modal analyses and the linear seismic response analyses are performed on a practical continuous rigid frame bridge with twin-legged piers with no tie beam, one tie beam and three tie beams of pier, using software Midas/civil. The findings indicate that installing tie beams of pier can increase the natural frequencies of this kind of bridge. Setting tie beams of pier is disadvantageous to the seismic performance of the bridge beam, but advantageous to improving the seismic performance of the twin-legged piers. The influence of tie beams of pier on the seismic performance on the whole structure is relevant to the pier height. These analytical results provide a reference for the seismic design and analysis of similar structures.

Seismic Design of High Rise Building in Shenyang

2012 ◽  
Vol 166-169 ◽  
pp. 2436-2443
Author(s):  
Rong Qin
Keyword(s):  
Seismic Performance ◽  
Seismic Design ◽  
Phase Iii ◽  
Structural Elements ◽  
Earthquake Scenarios ◽  
High Rise ◽  
Code Structure ◽  
Moderate Earthquake ◽  
Weak Points ◽  
Rare Earthquake

This paper examines the A1 tower of the Shenyang Huafu Xintiandi Phase III project as an example of an out of code structure. It also analyzes the seismic performance under three earthquake scenarios; a frequent earthquake, a moderate earthquake and a rare earthquake. This paper will discuss the structural elements design, and address the weak points. This paper also provides several seismic design enhancements for similar high-rise buildings.

Seismic Performance of Steel-Concrete Composite Rigid-Frame Bridge: Shake Table Test and Numerical Simulation

2020 ◽  
Vol 25 (7) ◽  
pp. 04020032 ◽  
Author(s):  
Yuanzheng Lin ◽  
Kaiming Bi ◽  
Zhouhong Zong ◽  
Hong Hao ◽  
Jin Lin ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Seismic Performance ◽  
Shake Table Test ◽  
Shake Table ◽  
Rigid Frame ◽  
Rigid Frame Bridge

Experimental Studies on Seismic Performance of Rigid-frame Extradosed Cable-stayed Bridges

2019 ◽  
Author(s):  
Xianzhi Wang ◽  
Jianzhong Li ◽  
Wei Guo
Keyword(s):  
Seismic Performance ◽  
Experimental Studies ◽  
Seismic Damage ◽  
Test Model ◽  
Test Results ◽  
Rigid Frame ◽  
Shake Tables ◽  
Tongji University ◽  
Design Construction ◽  
Cable Stayed Bridges

<p>With the aim of further understanding the seismic performance of extradosed cable-stayed bridges, this paper presents an experimental investigation of a three-pylon rigid-frame extradosed cable-stayed bridge by conducting 1/20 scaled longitudinal shake tables model tests at the laboratory of Tongji University, Shanghai, China. The design, construction and testing protocol of the test model are firstly introduced. Observation of the seismic damage situation and empirical data on the seismic responses of the test model are then provided. The test results show that: (1) severe seismic damage appeared at the bottom and upper parts of piers and damage at the bottom parts were much heavier; (2) no damage was observed on short pylons; (3) structural stiffness degradation occurred when PGA≥0.4g; (4) the vibration of the short pylon almost has no contribution in the displacement at the pylon top.</p>

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