scholarly journals Effect of Time-dependent Diffusion and Exterior Conditions on Service Life Considering Deterministic and Probabilistic Method

2016 ◽  
Vol 20 (6) ◽  
pp. 65-72
Author(s):  
Seung-Jun Kwon
Keyword(s):  
Service Life ◽  
Probabilistic Method ◽  
Time Dependent

scholarly journals Sensitivity of Service Life Extension and CO2 Emission due to Repairs by Silane Treatment Applied on Concrete Structures under Time-Dependent Chloride Attack

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Aruz Petcherdchoo
Keyword(s):  
Service Life ◽  
Concrete Structures ◽  
Treatment Strategies ◽  
Time Dependent ◽  
Life Extension ◽  
Silane Treatment ◽  
Application Time ◽  
Free Service ◽  
Chloride Attack ◽  
Service Life Extension

This paper presents sensitivity of service life extension and CO2 emission due to silane (alkyltriethoxysilane) treatment on concrete structures under time-dependent chloride attack. The service life is predicted by the Crank–Nicolson-based finite difference approach for avoiding the complexity in solving Fick’s second law. The complexity occurs due to time-dependent chloride attack and nonconstant diffusion coefficient of concrete with silane treatment. At the application time of silane treatment, the cumulative CO2 emission is assessed. The effectiveness of silane treatment is defined as the ratio of the service life extension to the cumulative CO2 emission assessed within the corrosion-free service life. The service life extension is defined as the difference between corrosion-free service life of concrete structures without and with time-based application of silane treatment. From the study, the diffusion of chlorides in concrete with silane treatment is found to be retarded. In comparison, the strategy without deterioration of silanes during effective duration is more suitable for service life extension but less effective than that with deterioration. In the sensitivity analysis, there are up to eight parameters to be determined. The service life of concrete structures without silane treatment is most sensitive to the water-to-cement ratio and the threshold depth of concrete structures. Considering only five parameters in silane treatment strategies, the service life is most sensitive to the first application time of silane treatment. The cumulative CO2 emission is most sensitive to either the first application time of silane treatment or the amount of CO2 emission per application.

Corrected Diffusion Model of Chloride in Concrete and its Engineering Application

2011 ◽  
Vol 189-193 ◽  
pp. 1886-1891
Author(s):  
Peng Fei Xue ◽  
Da Ling Mao
Keyword(s):  
Service Life ◽  
Diffusion Model ◽  
Life Prediction ◽  
Engineering Application ◽  
Time Dependent ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Practical Applications ◽  
Environment Variable ◽  
Stochastic Characteristic

A multi-factor diffusion model of chloride in concrete was formulated, in which the hypothesis of Fick’s Law were corrected through parameter definition. The values of the parameters in the model were given for practical applications according to pilot calculation and analysis of mass data. By using this diffusion model, three calculation methods of concrete structure service life were further deduced, it includes definite value method, probability performance based method and time-dependent reliability based method. The service life prediction for the approach bridge of Huang-pu Bridge was carried on by using various prediction approaches mentioned above. The results showed that: time-dependent reliability based method can consider randomness of chloride diffusion coefficient and the depth of concrete covering layer, and the stochastic characteristic of environment variable can be easily taken into account too. By adjusting the target reliability, the prediction results are consistent with those of the other two methods.

MODELING MANUFACTURERS' AND CUSTOMERS' COSTS FOR COST SHARING LIFETIME WARRANTY

2012 ◽  
Vol 29 (04) ◽  
pp. 1250024
Author(s):  
ANISUR RAHMAN ◽  
GOPINATH CHATTOPADHYAY
Keyword(s):  
Service Life ◽  
Stochastic Models ◽  
Cost Sharing ◽  
Poor Quality ◽  
Time Dependent ◽  
Cost Models ◽  
Reliable Service ◽  
Dependent Failures ◽  
Warranty Policies

Lifetime warranties are becoming more popular as these types of warranties provide assurance for a longer reliable service life, protection of customers against poor quality and the potential high cost of failure occurring during the long uncertain life of products. Chattopadhyay and Rahman (2008) proposed taxonomy for Lifetime warranty policies and developed cost models for Free rectification lifetime warranty (FRLTW) policies. In line with Chattopadhyay and Rahman, in this paper, stochastic models for two most potential and currently practiced Cost sharing lifetime warranty (CSLTW) policies, Specific parts excluded lifetime warranty and Limit on individual cost lifetime warranty have been developed to estimate the customers' and manufacturers' costs. The developed models capture the uncertainties of lifetime warranty coverage period and implication in offering such warranties on both manufacturer and customers. The developed models are analyzed using illustrative examples considering products with time-dependent failures.

scholarly journals Service Life Evaluation for RC Sewer Structure Repaired with Bacteria Mixed Coating: Through Probabilistic and Deterministic Method

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5424
Author(s):  
Hyun-Sub Yoon ◽  
Keun-Hyeok Yang ◽  
Kwang-Myong Lee ◽  
Seung-Jun Kwon
Keyword(s):  
Surface Roughness ◽  
Service Life ◽  
Coating Thickness ◽  
Probabilistic Method ◽  
Probabilistic Methods ◽  
Ion Concentration ◽  
Design Parameters ◽  
Deterministic Method ◽  
Repair Mortar ◽  
Life Evaluation

Since a concrete structure exposed to a sulfate environment is subject to surface ion ingress that yields cracking due to concrete swelling, its service life evaluation with an engineering modeling is very important. In this paper, cementitious repair materials containing bacteria, Rhodobacter capsulatus, and porous spores for immobilization were developed, and the service life of RC (Reinforced Concrete) structures with a developed bacteria-coating was evaluated through deterministic and probabilistic methods. Design parameters such protective coating thickness, diffusion coefficient, surface roughness, and exterior sulfate ion concentration were considered, and the service life was evaluated with the changing mean and coefficient of variation (COV) of each factor. From service life evaluation, more conservative results were evaluated with the probabilistic method than the deterministic method, and as a result of the analysis, coating thickness and surface roughness were derived as key design parameters for ensuring service life. In an environment exposed to an exterior sulfate concentration of 200 ppm, using the deterministic method, the service life was 17.3 years without repair, 19.7 years with normal repair mortar, and 29.6 years with the application of bacteria-coating. Additionally, when the probabilistic method is applied in the same environment, the service life was changed to 9.2–16.0 years, 10.5–18.2 years, and 15.4–27.4 years, respectively, depending on the variation of design parameters. The developed bacteria-coating technique showed a 1.47–1.50 times higher service life than the application of normal repair mortar, and the effect was much improved when it had a low COV of around 0.1.

Approach on the improvement of the durability of an electrorheological valve

2018 ◽  
Vol 29 (19) ◽  
pp. 3737-3747 ◽  
Author(s):  
Tobias Bauerochs ◽  
Stephan Ulrich ◽  
Steffen Schneider ◽  
Rainer Bruns
Keyword(s):  
Service Life ◽  
Field Strength ◽  
Pressure Difference ◽  
Operating Time ◽  
Electrorheological Fluid ◽  
Continuous Operation ◽  
Operating Conditions ◽  
Time Dependent ◽  
Electrorheological Effect

This work presents an approach on the improvement of the durability of an electrorheological valve and an electrorheological fluid. The pressure difference which can be achieved with the electrorheological effect is determined at the electrorheological valve. In order to simulate realistic operating conditions and to obtain a time-dependent pressure difference, several experiments are carried out in which the electrorheological fluid is permanently loaded over a period of several days with a field strength of up to 5 kV/mm. The results show that a simulated operating time of 2000 h would be possible without any problems. The knowledge gained on the characteristics of the electrorheological valve and electrorheological fluid in continuous operation is important for the design of electrorheological applications in order to estimate and determine their service life.

Assessment of time-dependent structural resistance of RC bridges in the Barak valley region, Assam, India

2022 ◽  
pp. 1-32
Author(s):  
Joydeep Das ◽  
Arjun Sil
Keyword(s):  
Service Life ◽  
Structural Reliability ◽  
Strength Loss ◽  
Time Dependent ◽  
Load Variations ◽  
Reliability Models ◽  
Condition Rating ◽  
Structural Resistance ◽  
Dependent Parameter ◽  
Existing Bridges

The reinforced concrete (RC) bridges deteriorate essentially due to strength loss induced by aging of the structure, extreme weathering conditions, and unplanned increased service loads. However, these load variations and aging factors equally could compromise structural reliability, and service life for continuous satisfactory operation of service bridges for future performance. A reasonable model of bridge strength and applied loads becomes the basis of accurate prediction of bridge functionality. Hence, time-dependent reliability approaches could be used efficiently to gain a reliable understanding of issues facing by the bridges in the study area for appropriate solutions. In this paper, the reliability of bridges under harsh conditions studied using time-variant and time-invariant reliability models in which both load and resistance considered as a time-dependent parameter. A combination of condition rating (CR) and time-dependent load employed to attain accurate insights about the degradation of structural resistance of the existing bridges. The result shows the significant impact of aging as well as traffic loads influence in the service life of both national highways (NH) and rural road service bridges. These observations might be used to adopt appropriate planning strategies as well as rational decisions to ensure the safety of the bridges for future operation.

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