scholarly journals Time-Variant Seismic Fragility of Offshore Continuous Beam Bridges Based on Collapse Analysis

2020 ◽  
Vol 10 (23) ◽  
pp. 8595
Author(s):  
Zhaodong Shi ◽  
Yan Liang ◽  
Yang Cao ◽  
Jialei Yan
Keyword(s):  
Working Conditions ◽  
Damage Model ◽  
Seismic Fragility ◽  
Time Varying ◽  
Bridge Structure ◽  
Damage State ◽  
Concrete Carbonation ◽  
Service Period ◽  
Whole Life Cycle ◽  
Bridge System

In this paper, the concrete carbonation and chloride-induced corrosion of bridge structure in the service period under the offshore environment were comprehensively considered. Based on the time-varying degradation effect of mechanical properties of materials and continuous damage model, the time-varying seismic fragility of bridge components was analyzed with using incremental dynamic analysis. The time-varying brittleness curves of the bridge system and components were established according to the results of the analysis. According to the analysis of the time-varying fragility of the structure in the complete damage state, the collapse working conditions of the bridge structure and a method of quantifying the fragility coefficient were proposed. The results show that the fragility coefficient of the bridge system is higher than that of the components in the whole life cycle, and all of them increase with the increase of the bridge service cycle. When the peak acceleration of ground is small, the removing of 1# pier is more fragile. When reaching the design service life, the fragility coefficient of the bridge system is about 30% higher than that of the original state. The fragility coefficient of the bridge system in removing of 1# is the maximum value between three working conditions.

scholarly journals Seismic Fragility Analysis of Bridge System Based on Fuzzy Failure Criteria

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Leping Ren ◽  
Shuanhai He ◽  
Haoyun Yuan ◽  
Zhao Zhu
Keyword(s):  
Structural Damage ◽  
Fragility Curves ◽  
Failure Criteria ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Actual Condition ◽  
Seismic Load ◽  
Analysis Method ◽  
Damage State ◽  
Bridge System

In the traditional bridge seismic fragility analysis, the criterion for judging the structural damage state is clear. That is to say, when the damage index exceeds a specific value, the structure is judged to enter the new damage state. However, the actual condition is that the boundary of structural damage is not clear but fuzzy. Taking a three-span V-shaped continuous girder bridge as an example, the damage process of the structure is described by fuzzy mathematics. Considering the uncertainties of ground motion and structure itself, a seismic fragility analysis method is established, which can consider the randomness of bridge itself, seismic load, and structural failure fuzziness simultaneously. Finally, the improved product of conditional marginal (I-PCM) method for fragility analysis of bridge system is further optimized and improved. The new improved method is used to form the seismic fragility curves of bridge structure system. The results show that it is possible to underestimate the potential seismic fragility of bridge components and system without considering the structural fuzzy failure criteria; the fragility curves formed by different membership functions are obviously different; the new system fragility analysis method can significantly improve the analysis accuracy.

scholarly journals Analysis on the Time-Varying Fragility of Offshore Concrete Bridge

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-22 ◽  
Author(s):  
Yan Liang ◽  
Jia-lei Yan ◽  
Jun-lei Wang ◽  
Peng Zhang ◽  
Bao-jie He
Keyword(s):  
Life Cycle ◽  
Damage Index ◽  
Nonlinear Dynamic Analysis ◽  
Seismic Fragility ◽  
Time Varying ◽  
Analysis Model ◽  
Seismic Capacity ◽  
Rigid Frame ◽  
Fragility Surface ◽  
Whole Life Cycle

For offshore bridges, the most prominent problem in the whole life cycle is that it is in an earthquake prone zone and an offshore corrosion environment at the same time. A nonlinear dynamic analysis model is set up for an offshore multispan and continuous rigid frame bridge based on the OpenSEES platform. The fragility surface of the bridge pier, bearing, bridge platform, and system are established by selecting a reasonable damage constitutive model of the material durability and a damage index analysis that studies the damage of the bridge durability to time-varying seismic fragility of bridge components and the system of the whole life cycle in offshore environment. The results show that the durability damage will lead to a constant decline in seismic capacity of the pier and an increase of the seismic demand under earthquake action as well as the probability to reach the ultimate failure state; compared to high piers, a low pier is more vulnerable to the offshore corrosion environment; the seismic fragility of bridge platform is higher than that of simply bearing; and the influence of offshore corrosion on environment is relatively large. With the prolongation of service period, the effect of durability damage on the seismic fragility of bridge system cannot be ignored in the coastal environment and it is necessary to make a reasonable evaluation on the seismic fragility of bridge structure during the whole life period.

scholarly journals Fault-Tolerant Control Strategy with Asymmetric Phase Currents for Single to Four-Phase Open-Circuit Faults of Six-Phase PMSM

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3163
Author(s):  
Chen Huang ◽  
Lidan Zhou ◽  
Zujia Cao ◽  
Gang Yao
Keyword(s):  
Working Conditions ◽  
Control Strategy ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Open Circuit ◽  
Time Varying ◽  
Electromagnetic Torque ◽  
Control Loops ◽  
Phase Current ◽  
Multi Phase

Multi-phase motors and generators are regarded with great fault tolerance capability, especially on open-circuit faults. Various mathematics analytical methods are applied for their fault control. In this paper, a fault-tolerant control strategy with asymmetric phase current for the open-circuit faults with arbitrary phases in the six-phase PMSM (six-phase permanent magnetic synchronous motor, 6P-PMSM) system, is proposed for better electrical and dynamical performance of the machine. An innovative mathematical model for PMSM under one to four-phase-open circuit faults are established considering the asymmetry of the machine. Combining with time-varying relations in machines’ working conditions, targeted decoupling transformation matrixes of every kind of open-circuit faults are settled by voltage equations under different faults. Modified control strategy with a connection between the neutral point and the inverter’s DC side is presented, which aims at increasing the system redundancy and reducing the amplitude of phase currents. Besides, improved control loops with two layers are put forward as well, with which the PMSM system acquires fewer harmonics in phase current and smoother electromagnetic torque. Simulation and experimental results of open-circuit faults are provided for verification of the theoretical analysis.

Seismic Fragility Analysis of Reinforced Concrete Frames with Service Life

2012 ◽  
Vol 446-449 ◽  
pp. 2313-2316
Author(s):  
Li Li Yuan ◽  
Jian Min Wang ◽  
Neng Jun Wang ◽  
Wen Ting Jiang
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Fragility Curve ◽  
Seismic Fragility ◽  
Concrete Frames ◽  
Damage State ◽  
Reinforced Concrete Frames ◽  
Nonlinear Mechanical ◽  
Interstorey Drift ◽  
Definition Of

An analytical method to obtain the seismic fragility curve of reinforced concrete frames with service life was proposed in this paper. Considering the variation of nonlinear mechanical characteristics of un-carbonated concrete with service life, the seismic fragility curve of frames was developed based on the interstorey drift corner in the weak storey of frame structures. According to the damage state definition of frames, each seismic fragility curve reflects the probability tendency of the defined damage state happening in frames with service life. It is helpful for the seismic performance analysis of reinforced concrete frames to use the proposed method.

Seismic fragility models of a bridge system based on copula method

2021 ◽  
pp. 875529302110525
Author(s):  
Libo Chen ◽  
Caigui Huang ◽  
Haiqiang Chen ◽  
Zhenfeng Zheng
Keyword(s):  
Seismic Performance ◽  
Marginal Distribution ◽  
Fragility Curves ◽  
Distribution Functions ◽  
System Level ◽  
Likelihood Method ◽  
Seismic Fragility ◽  
Distribution Model ◽  
Copula Models ◽  
Bridge System

Seismic fragility assessment widely uses a probabilistic measure for assessing the seismic performance of structural components or systems. This article proposes a copula-based seismic fragility (CBSF) method to derive the system-level damage probabilities of reinforced concrete bridges and to consider the correlation among seismic demands of components. First, the marginal distribution functions of the random variables are calibrated, and three Archimedean copula models are considered. Subsequently, the relevant parameters of the copula models are estimated using the semi-parametric maximum likelihood method. Next, the damage probabilities of a bridge system are calculated based on the joint distribution model with the most suitable copula model and the calibrated marginal distribution functions. Finally, the CBSF method is used to estimate the damage probability of a simply supported box girder bridge. The performance of the CBSF method is validated by a comparison of fragility curves obtained using the CBSF method and the probabilistic seismic demand analysis (PSDA) method. The comparative results demonstrate that the fragility curves obtained by the CBSF method are better than those obtained using the PSDA method. The proposed CBSF model can serve as a tool for assessing the seismic performance of structures and estimating the economic loss of existing bridge systems.

Simplified Expression for Seismic Fragility Estimation of Sliding-Dominated Equipment and Contents

2006 ◽  
Vol 22 (3) ◽  
pp. 709-732 ◽  
Author(s):  
Tara C. Hutchinson ◽  
Samit Ray Chaudhuri
Keyword(s):  
Fragility Curves ◽  
Input Parameter ◽  
Simple Expression ◽  
Seismic Fragility ◽  
Economic Losses ◽  
Distribution Profile ◽  
Damage State ◽  
Fragility Function ◽  
Daunting Task ◽  
Recent Earthquakes

Damage to small equipment and contents during seismic events has gained considerable attention following recent earthquakes, largely due to the potential for operational downtime, which results in significant economic losses. The estimation of losses from this interior building damage is a daunting task, due to the complexity of types of equipment and the randomness of their location within the structure. Nonetheless, a precursor to calculating such losses is a reasonable association between structural and nonstructural (equipment or contents) demands. Cast in a probabilistic framework, such an association is best represented through the use of seismic fragility curves, where the probabilities of exceeding a given damage state is correlated with an input parameter. In this paper, analytically developed seismic fragility curves for various unattached equipment and contents are calculated and presented. The emphasis of the study is on rigid scientific equipment and contents, which are often placed on the surface of ceramic laboratory benches in science laboratories or other buildings. Only uniaxial seismic excitation is considered to provide insight into the form of the fragility function. Generalized fragility curves are then developed and a simple expression is presented, which is envisioned to be very useful from a design perspective. The usefulness of the proposed expression is illustrated via a simple numerical example coupled with a design code-specified horizontal acceleration distribution profile for an example building structure.

Seismic Fragility Analysis of Reinforced Concrete Frames within Service Life

2012 ◽  
Vol 166-169 ◽  
pp. 2391-2394
Author(s):  
Neng Jun Wang ◽  
Jian Min Wang ◽  
Wen Ting Jiang
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Fragility Curve ◽  
Seismic Fragility ◽  
Concrete Frames ◽  
Damage State ◽  
Reinforced Concrete Frames ◽  
Nonlinear Mechanical ◽  
Damage States ◽  
Change Tendency

An analytical method was proposed to obtain the seismic fragility curve of reinforced concrete frames within the service life. Considering the variation law of nonlinear mechanical characteristics of un-carbonated concrete within service life, the seismic fragility curve of frames was developed based on the inter-storey drift corner in the weak storey of frame structures. According to the defined frame damage states, each seismic fragility curve reflects the probability change tendency of the defined damage state in frames within service life. A numerical example was modeled to illustrate the variation characteristic of seismic fragility within the service life.

scholarly journals Study on hydration heat of concrete channel-box girder

2020 ◽  
pp. 257-257
Author(s):  
Xiangnan Xiao ◽  
Yunyong Peng ◽  
Guijun Luo
Keyword(s):  
Tensile Strength ◽  
Temperature Field ◽  
Casting Process ◽  
Hydration Heat ◽  
Time Varying ◽  
Bridge Structure ◽  
Box Girder ◽  
Simply Supported ◽  
Concrete Shrinkage ◽  
Shrinkage And Creep

Temperature is one of the important reasons causing the cracks on the bridge structure during the construction and operation. In this paper, the temperature field produced by hydration heat and early thermal stress of a 64m simply supported channel-box girder are simulated during casting process, considering the time-varying characteristics of concrete shrinkage and creep, elastic modulus and tensile strength. Then, various parameters influencing the temperature field are analyzed, and the corresponding measures of controlling temperature cracks are proposed.

scholarly journals Performance Assessment of Interaction Soil Pile Structure Using the Fragility Methodology

2021 ◽  
Vol 7 (2) ◽  
pp. 376-398
Author(s):  
Guettafi Nesrine ◽  
Yahiaoui Djarir ◽  
Abbeche Khelifa ◽  
Bouzid Tayeb
Keyword(s):  
Axial Load ◽  
Fragility Curves ◽  
Pushover Analysis ◽  
Nonlinear Static Analysis ◽  
Seismic Fragility ◽  
Damage State ◽  
Steel Ratio ◽  
Lateral Capacity ◽  
And Performance ◽  
Loose Medium

This study aimed to investigate whether the seismic fragility and performance of interaction soil-pile-structure (ISPS) were affected by different parameters:  axial load, a section of the pile, and the longitudinal steel ratio of the pile were implanted in different type of sand (loose, medium, dense). In order to better understand the ISPS phenomena, a series of nonlinear static analysis have been conducted for two different cases, namely: (i) fixed system and (ii) ISPS system, to get the curves of the capacity of every parameter for developing the fragility curve. After a comparison of the numerical results of pushover analysis and fragility curves, the results indicate that these parameters are significantly influenced on lateral capacity, ductility and seismic fragility on the ISPS. The increasing in the axial load exhibit high probabilities of exceeding the damage state. The increase in pile section and longitudinal steel ratio, the effect of probability damage (low and high) are not only related to the propriety geometrically, but also related to the values of ductility and lateral capacity of the system. Doi: 10.28991/cej-2021-03091660 Full Text: PDF

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