scholarly journals Probabilistic optimization of fatigue maintenance for welded components in steel bridges based on LEFM and LCCM

2018 ◽  
Vol 38 (2) ◽  
pp. 166-174 ◽  
Author(s):  
Yong Zeng ◽  
Hongmei Tan ◽  
Dahan Chen
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Steel Structures ◽  
Steel Bridges ◽  
Maintenance Cost ◽  
Optimal Time ◽  
Maintenance Optimization ◽  
Time Interval ◽  
Optimization Strategy ◽  
Inspection Cost

In this paper a probabilistic-based method for fatigue maintenance optimization of steel bridge’s welded joints, combined with linear elastic fracture mechanics (LEFM), the structure reliability, and life cycle cost method(LCCM) is proposed. The probabilistic analysis method can be used with the fatigue maintenance of steel bridges. Weld cracks are classified by its size and maintenance decisions, and are made according to its size classification. Maintenance cost is divided into inspection, repair and failure costs, according to the life cycle cost method. The maintenance optimization strategy is transformed to minimize the expected lifetime total costs with the constraints of the minimum acceptable reliability index to attain the most cost-optimal inspection and repair for the balanced costs between risk and safety. An example concerning the transverse stiffeners of welded components in the main girder of suspension bridge is investigated through the research of some parameters sensitivity. Among all the parameters, the inspection cost is the most remarkable. The optimal time interval of repair will delay based on the increase of the inspection cost. The optimal time interval of repair will advance based on the increase of repair cost. A discount rate can drastically change the value of the total cost, but when the probability of failure is very small, the increase of failure cost has little effect on the optimal time interval of repair. The method presented in this paper can be conducted using the similar maintenance of steel structures.

scholarly journals Life Cycle Cost of Electricity Production: A Comparative Study of Coal-Fired, Biomass, and Wind Power in China

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3463
Author(s):  
Xueliang Yuan ◽  
Leping Chen ◽  
Xuerou Sheng ◽  
Mengyue Liu ◽  
Yue Xu ◽  
...  
Keyword(s):  
Power Generation ◽  
Life Cycle ◽  
Wind Power ◽  
Life Cycle Cost ◽  
Raw Material ◽  
Electricity Production ◽  
Maintenance Cost ◽  
External Cost ◽  
Levelized Cost Of Electricity ◽  
Cost Of Electricity

Economic cost is decisive for the development of different power generation. Life cycle cost (LCC) is a useful tool in calculating the cost at all life stages of electricity generation. This study improves the levelized cost of electricity (LCOE) model as the LCC calculation methods from three aspects, including considering the quantification of external cost, expanding the compositions of internal cost, and discounting power generation. The improved LCOE model is applied to three representative kinds of power generation, namely, coal-fired, biomass, and wind power in China, in the base year 2015. The external cost is quantified based on the ReCiPe model and an economic value conversion factor system. Results show that the internal cost of coal-fired, biomass, and wind power are 0.049, 0.098, and 0.081 USD/kWh, separately. With the quantification of external cost, the LCCs of the three are 0.275, 0.249, and 0.081 USD/kWh, respectively. Sensitivity analysis is conducted on the discount rate and five cost factors, namely, the capital cost, raw material cost, operational and maintenance cost (O&M cost), other annual costs, and external costs. The results provide a quantitative reference for decision makings of electricity production and consumption.

Integrating Reliability Analysis in Life Cycle Cost Estimation of Heat Exchanger and Pump

2014 ◽  
Vol 903 ◽  
pp. 408-413 ◽  
Author(s):  
FRESELAM Mulubrhan ◽  
Ainul Akmar Mokhtar ◽  
Masdi Muhammad
Keyword(s):  
Life Cycle ◽  
Heat Exchanger ◽  
Cost Estimation ◽  
Life Cycle Cost ◽  
Distribution Model ◽  
Maintenance Cost ◽  
Published Data ◽  
Acquisition Costs ◽  
Maintenance Policies ◽  
High Degree

This paper presents a mathematical model to estimate the life cycle cost (LCC) of heat exchanger and pump. Maintenance cost, down time cost and acquisition costs are calculated. The main uncertainty in calculating these costs are prediction of number of failure and cumulative down time. Number of failure is determined using failure and repair time density function. According to the characteristic that the cumulative failure probability observed, a Weibull distribution model is used. The scale and shape parameters of the Weibull are extracted from the published data. The results of the study show that 71.3% loss in the reliability of heat exchanger and 34.2% reliability loss in pump could lead to 66.2 % increment of the total cost. The reliability of the system decreases because of number of failures will increase each year, and this failure leads to unavailability of the system.Therefore in order to achieve higher system effectiveness and reduce the total LCC, the reliability of the systems need to be increased through proper maintenance policies and strategies. The results of the study could assist the managers to make decision with high degree of accuracy.

Performance Evaluation of Seismic Force–Resisting Systems for Low-Rise Steel Buildings in Canada

2015 ◽  
Vol 31 (4) ◽  
pp. 1969-1990 ◽  
Author(s):  
T. Y. Yang ◽  
M. Murphy
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Seismic Damage ◽  
Maintenance Cost ◽  
Life Cycle Costs ◽  
Finite Element Models ◽  
Steel Buildings ◽  
Material Usage ◽  
Seismic Force ◽  
Seismic System

Steel is one of the most popular seismic force–resisting systems (SFRS) in use worldwide. In Canada, several SFRS have been prequalified for use in the national and provincial building codes. The design of each SFRS has been covered comprehensively in literature. However, no guidance has been provided in selecting the optimum system for a project. In this paper, a prototype building located in Vancouver, Canada, was designed nine times to utilize each of the prequalified SFRS. Detailed seismic hazard and finite element models were developed for each system. The performance in terms of initial construction and life-cycle cost was used to rank each SFRS. The result of this analysis shows that the eccentrically braced configuration has the lowest material usage and life cycle maintenance cost; it is therefore the most economic system in this study. The presented methodology is transparent and can be easily adopted by engineers to select the most economic seismic system for projects with different configurations and geometries than those given in this research. Furthermore, this system introduces a metric with which to estimate the life-cycle costs of a structure taking into account seismic damage over the service life.

Life Cycle Cost Management Strategy on Corrosion Deterioration and Fatigue Damage of Steel Girder Bridge

2008 ◽  
Vol 385-387 ◽  
pp. 845-848
Author(s):  
Moe M.S. Cheung ◽  
Kevin K.L. So ◽  
Xue Qing Zhang
Keyword(s):  
Life Cycle ◽  
Fatigue Damage ◽  
Life Cycle Cost ◽  
Management Strategies ◽  
Maintenance Cost ◽  
Steel Girder ◽  
Damage Models ◽  
Failure Cost ◽  
Steel Girder Bridge ◽  
Girder Bridge

This paper proposes a life-cycle cost (LCC) management methodology that integrates corrosion deterioration and fatigue damage mechanisms. This LCC management methodology has four characterized features: (1) corrosion deterioration and fatigue damage models are used to predict the time when the pre-defined limits are reached; (2) the performance of the steel girder is measured by condition state sets in which deflection, moment and shear capacities and fatigue strength limits are considered altogether; (3) the cost-effectiveness of management strategies are measured by the performance improvement per unit of money spent; and (4) the LCC model includes initial design/construction cost, inspection cost, maintenance cost, repair/rehabilitation cost and failure cost. A steel girder bridge is used as an example to demonstrate the application of the proposed LCC management methodology.

Innovative Approach for Use of Hydrofoils on Ultralight Seaplane

2020 ◽  
Author(s):  
Antonio Maglione ◽  
Ubaldo Cella ◽  
Marco E. Biancolini ◽  
Leonardo Lecce
Keyword(s):  
Life Cycle ◽  
Power Plant ◽  
Life Cycle Cost ◽  
Water Surface ◽  
Maintenance Cost ◽  
Wave Forces ◽  
Water Spray ◽  
Sea State ◽  
Important Benefit ◽  
Plant Maintenance

Retractable hydrofoils may enhance performances of seaplane during take-off and landing runs by lowering the speed when the hull is leaving or touching water surface. Hydrofoils are designed to complement airlift with additional hydrodynamic lift elevating the hull above the water at a speed lower than take-off speed; this minimizes slamming phenomenon on the hull, improving seakeeping capability of the seaplane, since water impacts are minimized compared to conventional configuration and, as a consequence, forces and accelerations on airframe, crew and passengers are reduced. This is of foremost importance on ultralight seaplanes, where wave forces acting on the relatively small aircraft mass provide high accelerations and significant roll, pitch and yaw forces that are higher on light aircraft compared to heavy seaplanes. As matter of facts, clear advantage of this configuration is the increase of sea state when a light seaplane can safely fly, providing additional useful days along the year. Important benefit is the improvement of seaplane performances during take-off and landing, reducing duration of the most critical flight phases, increasing overall safety and reducing pilot workload. Further benefits are envisioned, with optimization of wing, empennage and fuselage to minimize aero-drag and, as snow-ball effect, mission fuel consumption and energy power requirements. Life-cycle cost receives benefits too, since less water spray is ingested by engine and less water droplets impinge on fast revolving propeller, thus reducing expensive power plant maintenance cost over the entire service life.

A Life Cycle Cost Analysis Approach for Selection of a Typical Heavy Usage Multistage Centrifugal Pump

2006 ◽  
Author(s):  
Laxman Y. Waghmode ◽  
Ravindra S. Birajdar ◽  
Shridhar G. Joshi
Keyword(s):  
Life Cycle ◽  
Cost Analysis ◽  
Centrifugal Pump ◽  
Life Cycle Cost ◽  
Lifetime Cost ◽  
Maintenance Cost ◽  
Life Cycle Costs ◽  
Life Cycle Cost Analysis ◽  
Initial Cost ◽  
Multistage Centrifugal Pump

It is well known that the pumps are the largest consumers of industrial motor energy and account for more than 25% of electricity consumption. The life cycle cost of a pump is the total lifetime cost associated with procurement, installation, operation, maintenance and its disposal. For majority of heavy usage pumps, the lifetime energy and/or maintenance cost will dominate the life cycle costs. Hence a greater understanding of all the cost components making up the total life cycle costs should provide an opportunity to achieve a substantial savings in energy and maintenance costs. This will further enable optimizing pumping system efficiency and improving pump and system reliability. Therefore in this context, the life cycle cost analysis of heavy usage pumps is quite important. This paper focuses on an application of a methodology of determining the life cycle cost of a typical heavy usage multistage centrifugal pump. In this case, all the cost components associated with the pump-set have been determined and classified under different categories. The data with regard to initial investment costs, operation costs, maintenance and repair costs and disposal costs for the pump considered for this case study was collected from the concerned pump manufacturer along with the unit cost of each component, quantity used and their weights. By applying the principles of reliability and maintainability engineering and using the data obtained from the design, manufacturing and maintenance departments, the component-wise values of MTBF (Mean Time Between Failures) and MTTR (Mean Time To Repair) were estimated. The results of the life cycle cost analysis of the specimen pump were compared with the life cycle costs of similar pumps reported in the literature. From this comparison of results, it can be concluded that, the initial cost of the pump is the only a fraction of the total life cycle cost. The operating cost of the pump dominates the life cycle costs especially in case of heavy usage pumps. The maintenance cost varies approximately from 0.6 to 2.5 times the initial cost of the pump. The life cycle cost of the pump varies approximately from 12 to 33 times the initial cost of the pump. The operation and maintenance cost is almost 92 to 97 per cent of the life cycle cost. The detailed analysis carried out in this paper is expected to provide guidelines to the pump manufactures/practicing engineers in selecting a heavy usage multistage centrifugal pump based on the total lifetime cost rather than only on initial price.

VERIFICATION OF REPAIR PAINTING EFFECT OF CORRODED WEATHERING STEEL BY EXPOSURE TEST

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Yuka Sugiyama ◽  
Toshihiko Aso ◽  
Atsumi Imai ◽  
Hiroaki Matsumoto
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Steel Surface ◽  
Steel Bridges ◽  
The Other ◽  
Weathering Steel ◽  
Water Leakage ◽  
Exposure Test ◽  
Repair Technique ◽  
Organic Zinc

Weathering steel generates dense protective rust on the steel surface. Since this protective rust would reduce corrosion speed, weathering steel can be used without any painting. Furthermore, the Life Cycle Cost of unpainted steel bridges would be lower than ordinary painted steel bridges. Due to these advantages, many weathering steel bridges have been constructed in recent years. Unfortunately, the generation of anomalous rust has been reported in some bridges, cause of water leakage or deicer. It is necessary to repair these bridges, but the repair technique for corroded weathering steel has never been established yet. This study aims to clarify the effect of various repair painting for corroded weathering steel by performing an exposure test. The exposure test has been carried out from September 2015 to Okinawa and Yamaguchi. Test in Okinawa is supplied airborne salt, and the test in Yamaguchi is not supplied airborne salt. Specimens, which produced anomalous rust, were repaired by 19 methods and exposed. As a result, it is effective to repair by organic zinc-rich paint in the area with airborne salt. On the other hand, it is appropriate to remove rust and salt on the steel surface by blasting in the area which is not supplied airborne salt.

scholarly journals Uncertainty estimation in railway track life-cycle cost: a case study from Swedish National Rail Administration

2008 ◽  
Vol 223 (3) ◽  
pp. 285-293 ◽  
Author(s):  
A P Patra ◽  
P Söderholm ◽  
U Kumar
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Cost Effective ◽  
Railway Track ◽  
Statistical Characteristics ◽  
Maintenance Cost ◽  
Cost Models ◽  
Effective Decision ◽  
Effective Decision Support

Life-cycle cost (LCC) is used as a cost-effective decision support for maintenance of railway track infrastructure. However, a fair degree of uncertainty associated with the estimation of LCC is due to the statistical characteristics of reliability and maintainability parameters. This paper presents a methodology for estimation of uncertainty linked with LCC, by a combination of design of experiment and Monte Carlo simulation. The proposed methodology is illustrated by a case study of Banverket (Swedish National Rail Administration). The paper also includes developed maintenance cost models for track.

Life Cycle Cost Analysis for Substation

2014 ◽  
Vol 638-640 ◽  
pp. 2370-2376
Author(s):  
Yan Zheng ◽  
Di Su ◽  
Xu Wang ◽  
Yu Cai
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Maintenance Cost ◽  
Cost Estimating ◽  
Engineering Project ◽  
Construction Engineering ◽  
Engineering Project Management ◽  
The Cost ◽  
The Relationship ◽  
Cost Of Construction

Life Cycle Cost of Construction engineering project management is a combination of modern management theory—system theory, cybernetics and information theory combined with the construction project. In this paper, a model of substation life cycle cost is built comprehensively, by making a model for the cost estimating of substation design and construction cost. Meanwhile, the operation loss, operation maintenance cost are analyzed and calculated, the estimate of the retirement costs is carried on. On these basics, analyzes the relationship between the cost, then the numerical example is given ultimately. Eventually, optimal reliability and economical efficiency is achieved.

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