scholarly journals Threshold selection for extreme value estimation of vehicle load effect on bridges

2018 ◽  
Vol 14 (2) ◽  
pp. 155014771875769 ◽  
Author(s):  
Xia Yang ◽  
Jing Zhang ◽  
Wei-Xin Ren
Keyword(s):  
Extreme Value ◽  
Parameters Estimation ◽  
Engineering Practice ◽  
Threshold Selection ◽  
Load Effect ◽  
Vehicle Load ◽  
Parent Distribution ◽  
Strain Data ◽  
Value Estimation ◽  
Vehicle Loads

In the design and condition assessment of bridges, the extreme vehicle load effects are necessary to be taken into consideration, which may occur during the service period of bridges. In order to obtain an accurate extrapolation of the extreme value based on limited duration, threshold selection is a critical step in the peak-over-threshold method. Overly high threshold results in little information to be used and excessively low threshold leads to large bias in parameters estimation of generalized Pareto distribution. To investigate this issue, 417 days of strain data acquired from the long-term structural health monitoring system of Taiping Lake Bridge in China are employed in this article. According to the tail distribution of the strain data induced by vehicle loads, four homothetic distributions are chosen as its parent distribution, from which lots of random samples are generated by the Monte Carlo method. For each parent distribution, the 100-yearly extreme values at different thresholds are estimated and compared with the theoretical value based on those samples. Then a simple and empirical threshold selection method is proposed and applied to estimate the weekly extreme strain due to vehicle loads on the Taiping Lake Bridge. Results show that the estimate on the basis of the threshold obtained by the proposed method is closer to the measured result than the commonly used methods. The proposed method can be an effective threshold selection tool for the extreme value estimation of vehicle load effect in future engineering practice.

scholarly journals Threshold Selection for POT Framework in the Extreme Vehicle Loads Analysis Based on Multiple Criteria

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Guangrun Wu ◽  
Wenliang Qiu
Keyword(s):  
Extreme Value ◽  
Entropy Method ◽  
Distribution Functions ◽  
Multiple Criteria ◽  
Extreme Value Analysis ◽  
Threshold Selection ◽  
Value Analysis ◽  
Extreme Load ◽  
Test Criteria ◽  
Vehicle Loads

Extreme value of vehicle load plays an important role in bridge design and risk assessment. Peaks over threshold (POT) is a method commonly used in extreme load estimation. The selection of thresholds for the POT method is extremely crucial, but the selected optimal threshold varies under different test criteria. Therefore, a method to select the suitable threshold is developed based on multiple criteria decision analysis (MCDA) in the paper. In MCDA, Chi-Square (χ2) test, Kolmogorov–Smirnov (K–S) test, and Root Mean Square Error (RMSE) in probability distribution functions (PDF) are employed as the test criteria and the weight of these criteria is calculated using the entropy method. Finally, vehicle loads obtained from simulation and field measurement are adopted to validate the effectiveness and feasibility of the proposed method. The results indicate that the proposed MCDA is a useful and complementary tool for threshold selection in the extreme value analysis.

scholarly journals The Mechanical Properties of Reinforced Concrete Plate-Girders when Placed Under Repeated Simulated Vehicle Loads

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1831
Author(s):  
Jinquan Zhang ◽  
Pengfei Li ◽  
Yan Mao ◽  
Zhenhua Dong
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Repeated Loading ◽  
Test Beam ◽  
Load Effect ◽  
Plate Girders ◽  
Concrete Plate ◽  
Vehicle Load ◽  
Vehicle Loads

The effect of vehicle loads on reinforced concrete plate-girders was evaluated using the current Chinese specifications. Repeated loading performance tests with loading amplitudes of 77 kN, 97 kN, and 121 kN, which correspond to the standard vehicle load, 1.25 times overload, and 1.6 times overload proportions effect were carried out on three full-scale simply-supported reinforced concrete plate-girders. Our research results indicate that the development of cracks in reinforced concrete beams can be divided into three stages: rapid development, stability, and failure. During the entire process, the strain of steel and concrete did not reach their yield strain. The most severe damage done to the concrete beams was the brittle fractures caused by the fatigue fracturing of the rebar. When in a stable condition, the extent to which the vehicle was overloaded had a significant effect on the fatigue performance of the beam, and the corresponding residual deflection and residual strain increased with the rise in the overload proportion. In addition, as the overload proportion increased, the stiffness degradation and the cumulative damage that occurred under the same loading cycle was more significant. The test beam reached failure after being subjected to 350,000 and 670,000 repeated loading cycles, when the load was 1.6 times and 1.25 times of the standard load effect. With a standard vehicle load effect, the test beam was able to endure 2,000,000 repeated load cycles with no significant degradation in stiffness and bearing capacity.

scholarly journals Threshold selection in univariate extreme value analysis

Extremes ◽  
2021 ◽  
Author(s):  
Laura Fee Schneider ◽  
Andrea Krajina ◽  
Tatyana Krivobokova
Keyword(s):  
Mean Squared Error ◽  
Extreme Value ◽  
Hill Estimator ◽  
Small Samples ◽  
Extreme Value Analysis ◽  
Threshold Selection ◽  
Value Analysis ◽  
Wide Range ◽  
Asymptotic Mean Squared Error ◽  
The Hill

AbstractThreshold selection plays a key role in various aspects of statistical inference of rare events. In this work, two new threshold selection methods are introduced. The first approach measures the fit of the exponential approximation above a threshold and achieves good performance in small samples. The second method smoothly estimates the asymptotic mean squared error of the Hill estimator and performs consistently well over a wide range of processes. Both methods are analyzed theoretically, compared to existing procedures in an extensive simulation study and applied to a dataset of financial losses, where the underlying extreme value index is assumed to vary over time.

Vehicle Load Effect of Long-Span Bridges

2015 ◽  
Vol 2481 (1) ◽  
pp. 132-139 ◽  
Author(s):  
Jun Wu ◽  
Fei Yang ◽  
Wanshui Han ◽  
Liujie Wu ◽  
Qiang Xiao ◽  
...  
Keyword(s):  
Load Effect ◽  
Long Span Bridges ◽  
Long Span ◽  
Vehicle Load

Hermite Extreme Value Estimation of Non-Gaussian Wind Load Process on a Long-Span Roof Structure

2014 ◽  
Vol 140 (9) ◽  
pp. 04014061 ◽  
Author(s):  
M. F. Huang ◽  
Wenjuan Lou ◽  
Xiaotao Pan ◽  
C. M. Chan ◽  
Q. S. Li
Keyword(s):  
Wind Load ◽  
Extreme Value ◽  
Long Span ◽  
Roof Structure ◽  
Value Estimation ◽  
Non Gaussian

Consideration of Epistemic Uncertainty in Extreme Wave Height Estimation

2014 ◽  
Author(s):  
Ryota Wada ◽  
Takuji Waseda
Keyword(s):  
Gulf Of Mexico ◽  
Observational Data ◽  
Wave Height ◽  
Extreme Values ◽  
Epistemic Uncertainty ◽  
Extreme Value Distribution ◽  
Predictive Distribution ◽  
Extreme Value ◽  
Posterior Predictive Distribution ◽  
Value Estimation

Extreme value estimation of significant wave height is essential for designing robust and economically efficient ocean structures. But in most cases, the duration of observational wave data is not efficient to make a precise estimation of the extreme value for the desired period. When we focus on hurricane dominated oceans, the situation gets worse. The uncertainty of the extreme value estimation is the main topic of this paper. We use Likelihood-Weighted Method (LWM), a method that can quantify the uncertainty of extreme value estimation in terms of aleatory and epistemic uncertainty. We considered the extreme values of hurricane-dominated regions such as Japan and Gulf of Mexico. Though observational data is available for more than 30 years in Gulf of Mexico, the epistemic uncertainty for 100-year return period value is notably large. Extreme value estimation from 10-year duration of observational data, which is a typical case in Japan, gave a Coefficient of Variance of 43%. This may have impact on the design rules of ocean structures. Also, the consideration of epistemic uncertainty gives rational explanation for the past extreme events, which were considered as abnormal. Expected Extreme Value distribution (EEV), which is the posterior predictive distribution, defined better extreme values considering the epistemic uncertainty.

Reliability Assessment of Fatigue Life of Hangers in Large-Span Suspension Bridges

2011 ◽  
Vol 147 ◽  
pp. 149-152
Author(s):  
Yong Zeng ◽  
Hong Mei Tan
Keyword(s):  
Time History ◽  
Public Confidence ◽  
Suspension Bridges ◽  
Fatigue Reliability ◽  
Load Spectrum ◽  
Accurate Analysis ◽  
Vehicle Load ◽  
History Of ◽  
Vehicle Loads ◽  
Main Cables

Hangers are very important components for suspension bridges, which link main cables and stiffening girders. When in service, hangers are much vulnerable to fatigue loads due to kinds of traffic flows, which may reduce the remaining life of the hangers and increase the risk of losing public confidence in cable supported bridges. In order to quantify the reliability of hangers under vehicle loads, fatigue reliability formula of hangers is proposed in this paper. Based on the accurate analysis of vehicle load spectrum, the time history of hangers is simulated and maintenance strategy is proposed.

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