Comparisons of prediction models for time-dependent reliability forecasting of bridge structures based on SHM data

2014 ◽  
pp. 543-549
Author(s):  
X Fan ◽  
D Lu
Keyword(s):  
Prediction Models ◽  
Time Dependent ◽  
Bridge Structures

Applications of Time-Dependent Analysis in the Design of Hybrid Bridge Structures

PCI Journal ◽  
2001 ◽  
Vol 46 (4) ◽  
pp. 56-74 ◽  
Author(s):  
Jiri Strasky ◽  
Jaroslav Navratil ◽  
Stanislav Susky
Keyword(s):  
Time Dependent ◽  
Hybrid Bridge ◽  
Bridge Structures ◽  
Time Dependent Analysis

Time-dependent deformations of concrete columns under different construction load histories

2019 ◽  
Vol 22 (8) ◽  
pp. 1845-1854 ◽  
Author(s):  
Dujian Zou ◽  
Chengcheng Du ◽  
Tiejun Liu ◽  
Jun Teng ◽  
Hanbin Cheng
Keyword(s):  
Prediction Models ◽  
Plain Concrete ◽  
Concrete Columns ◽  
In Situ Monitoring ◽  
Time Dependent ◽  
Construction Stage ◽  
Inappropriate Use ◽  
High Rise ◽  
Multi Stage ◽  
Axial Shortening

The adverse effects caused by differential axial shortening in high-rise buildings have received increasing attention with growing building height. However, the axial shortening analysis still lacks accuracy compared to the in-situ monitoring results of practical high-rise buildings during construction stage. It is imperative to identify the error sources, and the applicability of the current shortening prediction models should be test verified. In this study, 14 plain concrete columns were cast, and the multi-stage load method was applied to approximately simulate the loading history of axial concrete members during construction stage. The time-dependent deformations of loaded concrete specimens were measured, and a comparative analysis was conducted between test results and numerical prediction values. It is found that the measured deformations of multi-stage loading cases are all underestimated compared with predicted results, and this underestimation may be mainly caused by the inappropriate use of elastic modulus. It further indicates that the axial shortening analysis of high-rise buildings tends to underestimate the actual shortening value when the traditional calculation method is used. This study provides a reference for explaining the mismatch between the analytical results and the actual shortening values.

Study on Prediction Models for Time-Dependent Settlement of Soft Road Foundation

2012 ◽  
Vol 204-208 ◽  
pp. 1880-1885
Author(s):  
Ai Zhao Zhou ◽  
Wei Wei Gu ◽  
Wei wang
Keyword(s):  
Prediction Models ◽  
Soft Clay ◽  
Gompertz Model ◽  
Weibull Model ◽  
Time Dependent ◽  
Observation Data ◽  
Soil Consolidation ◽  
Proposed Model ◽  
Total Settlement ◽  
Ultimate Settlement

The characteristics of soft clay roadbed settlement prediction model are studied in this paper. Firstly, based on one-dimension soil consolidation theory, the shape of time-dependent settlement process curve was analysed. Then, Mathematical analysis of traditional settlement models, including Gompertz model and Logistic model, was conducted, and the mathematical deficiency of above two traditional models were pointed out, which the settlement corresponding to inflection point has a constant ratio to the ultimate settlement. Further, Weibull model was proposed to describe the time-dependent settlement process of roadbed. This proposed model overcomes the deficiency of above two traditional models, and exponent model is one of its degraded expressions. Moreover, it can predict the total settlement processes of both the instantaneous load and the ramp load conditions. Finally, according to a group settlement observation data, the prediction results of different models are compared, and Weibull model has a good agreements.

Estimating a time-dependent concordance index for survival prediction models with covariate dependent censoring

2012 ◽  
Vol 32 (13) ◽  
pp. 2173-2184 ◽  
Author(s):  
Thomas A. Gerds ◽  
Michael W. Kattan ◽  
Martin Schumacher ◽  
Changhong Yu
Keyword(s):  
Prediction Models ◽  
Dependent Censoring ◽  
Time Dependent ◽  
Survival Prediction ◽  
Concordance Index

Ice Accretion of Glaze Loads Model on Wires of Power Transmission Lines

2011 ◽  
Vol 189-193 ◽  
pp. 3225-3229
Author(s):  
Chun Cheng Liu ◽  
Jiao Liu
Keyword(s):  
Wind Speed ◽  
Transmission Lines ◽  
Prediction Models ◽  
Power Transmission ◽  
Time Dependent ◽  
Ice Accretion ◽  
Power Transmission Lines ◽  
Collision Efficiency ◽  
Accretion Model ◽  
Median Volume

In connection with the process of glaze ice, prediction models about height and thickness of ice coating under uniform and non-uniform ice accretion of wire are presented by taking into account local collision efficiency, freeze coefficient and collection coefficient based on the existing model at home and abroad. The time-dependent ice models on the conditions of different median volume diameter of super-cooled droplets, wind speed and wire diameter are analyzed. Compared with the existing model, the proposed ice accretion model performed well in predicting ice’s weight and thickness. At the same time, it can give some lights on ice disaster and anti-icing design for power transmission lines.

scholarly journals Bayesian Prediction of Pre-Stressed Concrete Bridge Deflection Using Finite Element Analysis

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4956
Author(s):  
Jaebeom Lee ◽  
Kyoung-Chan Lee ◽  
Sung-Han Sim ◽  
Junhwa Lee ◽  
Young-Joo Lee
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Prediction Models ◽  
Measurement Data ◽  
Element Model ◽  
Time Dependent ◽  
Probabilistic Prediction ◽  
Element Analysis ◽  
Actual Measurement ◽  
Railway Bridges

Vertical deflection has been emphasized as an important safety indicator in the management of railway bridges. Therefore, various standards and studies have suggested physics-based models for predicting the time-dependent deflection of railway bridges. However, these approaches may be limited by model errors caused by uncertainties in various factors, such as material properties, creep coefficient, and temperature. This study proposes a new Bayesian method that employs both a finite element model and actual measurement data. To overcome the limitations of an imperfect finite element model and a shortage of data, Gaussian process regression is introduced and modified to consider both, the finite element analysis results and actual measurement data. In addition, the probabilistic prediction model can be updated whenever additional measurement data is available. In this manner, a probabilistic prediction model, that is customized to a target bridge, can be obtained. The proposed method is applied to a pre-stressed concrete railway bridge in the construction stage in the Republic of Korea, as an example of a bridge for which accurate time-dependent deflection is difficult to predict, and measurement data are insufficient. Probabilistic prediction models are successfully derived by applying the proposed method, and the corresponding prediction results agree with the actual measurements, even though the bridge experienced large downward deflections during the construction stage. In addition, the practical uses of the prediction models are discussed.

Analysis of Structural Effects of Time-Dependent Behaviour of Concrete: an Internationally Harmonized Format – Recent Updates

2019 ◽  
pp. 4-18
Keyword(s):  
Reinforced Concrete ◽  
Linear Viscoelasticity ◽  
Prediction Models ◽  
Time Dependent ◽  
Honorary Member ◽  
Structural Effects ◽  
Previous Edition ◽  
Time Dependent Behaviour ◽  
Dependent Behaviour

Modern concrete structures, realized through complex sequential construction techniques and/or characterized by significant non-homogeneities, are in general very sensitive to the effects of time-dependent behaviour of concrete (creep and shrinkage). Guidelines for the evaluation of these effects were developed in the last decades by international pre-standard and standard institutions on the basis of a common, although progressively evolving, scientific background, and of a substantially worldwide harmonized format. The author discusses the development, with his large personal involvement, of this favourable scenario, evidencing areas of well established consensus and open problems. One pending problem is still represented by the uncertainties of prediction models, with particular regards to the multi-decade long-term prediction of creep. In what concerns the evaluation of the structural effects of creep, it is commonly accepted that a reliable analysis of the structural response in service conditions may be performed on the basis of the theory of ageing linear viscoelasticity, first established by Italian mathematician V. Volterra at the dawn of 20th century. The paper discusses the computational implications of this approach with reference on the one hand to the adoption of realistic advanced models for the prediction of the creep behaviour of concrete, and, on the other hand, to the complexity and sequential character of the constructions, and illustrates current updated guidelines developed at the international level for the evaluation of the effects of creep, both in the conceptual and preliminary design stages and in the subsequent detailed construction-stage and long-term reliability analyses of complex and sequential structures. These guidelines are intended to deal also with other phenomena, which are responsible of causing deviations from aging linear viscoelasticity, like tensile cracking, cyclic creep, and stress relaxation in prestressing tendons at variable strain, as well as the effects of humidity and temperature variations. The paper must be intended as a homage to the memory of CEB (Comité Euro-International du Béton, Euro-International Committee for Concrete) Honorary Member and member of the Academy of Construction and Architecture of the USSR Alexei A. Gvozdev, for long-time head of the laboratory of reinforced concrete of NIIZHB, the Institute for Concrete and Reinforced Concrete now named after him, for his crucial role in encouraging and assisting the author in the initial steps of transporting into CEB and FIP (Fédération Internationale de la Précontrainte, International Federation for Prestressing) ambient the fundaments of this new advanced format for creep analysis, to which the school of Soviet scientists and Gvozdev himself had given a fundamental contribution. The present edition of the paper incorporates some significant updates related to the advancement in the international debate, with respect to the previous edition published in the Journal “Industrial and Civil Engineering” (Promyshlennoe i grazhdanskoe stroitel’stvo) of December 2014.

Effect of Corrosion on Crack Development and Fatigue Life

1998 ◽  
Vol 1624 (1) ◽  
pp. 110-117 ◽  
Author(s):  
John W. Fisher ◽  
Eric J. Kaufmann ◽  
Alan W. Pense
Keyword(s):  
Fatigue Life ◽  
Weld Metal ◽  
Fatigue Cracking ◽  
High Strength ◽  
Time Dependent ◽  
Structural Behavior ◽  
The Past ◽  
Fatigue And Fracture ◽  
Bridge Structures

Fatigue and fracture as well as loss of section caused by corrosion are time-dependent performance characteristics that have the potential to jeopardize the integrity of bridge structures. During the past 25 years these conditions have developed in a number of bridges, resulting in loss of service, costly repairs, and concern about the safety of these structures. A review of the experience with such time-dependent damage since 1970 is presented. The experience is grouped into three categories: fatigue cracking resulting from changes in structural behavior as a result of corrosion, fatigue cracking resulting from development of corrosion notches in members, and stress corrosion of high-strength steel and weld metal. The examples cited illustrate the role of corrosion phenomena in bridge service and the need to control the corrosion conditions on bridge structures.

Resistance and Time-Variant Reliability Updating of Existing Bridge Structures Based on Proof Loads

2013 ◽  
Vol 540 ◽  
pp. 37-46 ◽  
Author(s):  
Da Gang Lu ◽  
Xue Ping Fan ◽  
Dong Fang Li
Keyword(s):  
Normal Distribution ◽  
Time Dependent ◽  
Reliability Model ◽  
Numerical Examples ◽  
Reliability Indices ◽  
Existing Structures ◽  
Bridge Structures ◽  
Existing Bridges ◽  
Stochastic Loads

Based on the characteristics of existing structures, the analyses were presented for an effect on the resistance of existing structures by using deterministic loads and stochastic loads. The calculating equations of the normal distribution and logarithmic normal distribution resistance under the deterministic proof load and the stochastic proof load were presented. Some valuable conclusions have been obtained for the calculating reliability of the existing structures. Based on the conclusions, time-dependent reliability model of the existing bridges was updated, the time-dependent reliability indices were solved with time integrated-discretized approach, and finally the numerical examples were presented.

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