scholarly journals Fatigue life assessment of TTC streetcar concrete pavements

2021 ◽  
Author(s):  
Bahram Farhang
Keyword(s):  
Life Cycle ◽  
Service Life ◽  
Fatigue Cracks ◽  
Fatigue Loading ◽  
Life Assessment ◽  
Superior Performance ◽  
Experimental Program ◽  
Impact Fatigue ◽  
Construction Methods ◽  
The Impact

The Toronto Transit Commission, TTC traditional embedded track for mechanically jointed rails, is performing satisfactory except for accelerated surface concrete deterioration. By far the most damaging group of deterioration processes in streetcars concrete pavement is due to wheel impact on the joints which will subsequently excite a response on the track. The enhancement of special trackwork, STW service life was the initiative to explore encapsulation technology advances in embedded track materials and construction methods. This aimed to extend the life cycle of the track from current average of 15 years towards target life of 50 years. In the present study, attempts at finding and patterning the localized cracks, especially wheel impact fatigue cracks, are carried out. This issue was investigated during the course of an experimental program demonstrated by simulating the wheel impact loading in concrete under repeated load application. Specially designed specimens were used to represent sheet rubber and urethane encapsulation system proposal against the current assembly. This research reviews the pros and cons of various factors influencing the life cycle of the current assembly and examining and assessing between alternative track construction methods and materials at the joints and examining the concrete's performance both during the impact fatigue loading resulting in inclined cracking and ongoing service life and durability issues under combined environmental and mechanical loadings. Experimental results show that it is possible to achieve the targeted service life of 50 years, based on minimum of 10 time superior performance for either of the proposed encapsulation technologies vs. current construction methods.

scholarly journals Fatigue life assessment of TTC streetcar concrete pavements

2021 ◽  
Author(s):  
Bahram Farhang
Keyword(s):  
Life Cycle ◽  
Service Life ◽  
Fatigue Cracks ◽  
Fatigue Loading ◽  
Life Assessment ◽  
Superior Performance ◽  
Experimental Program ◽  
Impact Fatigue ◽  
Construction Methods ◽  
The Impact

The Toronto Transit Commission, TTC traditional embedded track for mechanically jointed rails, is performing satisfactory except for accelerated surface concrete deterioration. By far the most damaging group of deterioration processes in streetcars concrete pavement is due to wheel impact on the joints which will subsequently excite a response on the track. The enhancement of special trackwork, STW service life was the initiative to explore encapsulation technology advances in embedded track materials and construction methods. This aimed to extend the life cycle of the track from current average of 15 years towards target life of 50 years. In the present study, attempts at finding and patterning the localized cracks, especially wheel impact fatigue cracks, are carried out. This issue was investigated during the course of an experimental program demonstrated by simulating the wheel impact loading in concrete under repeated load application. Specially designed specimens were used to represent sheet rubber and urethane encapsulation system proposal against the current assembly. This research reviews the pros and cons of various factors influencing the life cycle of the current assembly and examining and assessing between alternative track construction methods and materials at the joints and examining the concrete's performance both during the impact fatigue loading resulting in inclined cracking and ongoing service life and durability issues under combined environmental and mechanical loadings. Experimental results show that it is possible to achieve the targeted service life of 50 years, based on minimum of 10 time superior performance for either of the proposed encapsulation technologies vs. current construction methods.

On the Evaluation and Consideration of Fracture Mechanical Notch Support Within a Creep Fatigue Lifetime Assessment

2018 ◽  
Author(s):  
Christian Kontermann ◽  
Henning Almstedt ◽  
Falk Müller ◽  
Matthias Oechsner
Keyword(s):  
Fatigue Loading ◽  
Experimental Program ◽  
Energy Market ◽  
Steam Turbines ◽  
Fatigue Lifetime ◽  
Global Strain ◽  
Creep Fatigue ◽  
Main Components ◽  
Flexible Operation ◽  
The Impact

Changes within the global energy market and a demand for a more flexible operation of gas- and steam-turbines leads to higher utilization of main components and raises the question how to deal with this challenge. One strategy to encounter this is to increase the accuracy of the lifetime assessment by quantifying and reducing conservatisms. At first the impact of considering a fracture mechanical notch support under creep-fatigue loading is studied by discussing the results of an extensive experimental program performed on notched round-bars under global strain control. A proposal how to consider this fracture mechanical notch support within a lifetime assessment is part of the discussion of the second part. Here, a theoretical FEM-based concept is introduced and validated by comparing the theoretical prediction with the results of the previously mentioned experimental study. Finally, the applicability of the developed and validated FEM-based procedure is demonstrated.

scholarly journals RISK- ANALYSIS OF DIAGNOSTIC DIAGNOSIS DURING OPERATION OF SELF-PROPELLED LOADING CRANES OF THE ARROW TYPE

2020 ◽  
Vol 1 (154) ◽  
pp. 267-271
Author(s):  
О. Skrypnyk ◽  
V. Abrakitov ◽  
A. Stepanenko
Keyword(s):  
Service Life ◽  
Risk Analysis ◽  
Fatigue Cracks ◽  
Operating Conditions ◽  
Industrial Safety ◽  
Economic Damage ◽  
Safe Operation ◽  
Current Time ◽  
The Impact

The problem of managing the safe operation of hoisting machines with an expired service life is associated with solving extremely complex interrelated tasks through a set of organizational and technical measures aimed at establishing the actual risk and economic feasibility of further operation. The most important condition in this case is the conduct of an expert examination of industrial safety and technical diagnostics, the results of which make it possible to establish the real state of hoisting machines at the current time. The safety of hoisting machines, including after the expiration of the standard service life (assigned resource), is associated with design features, workmanship, installation quality, their operation modes and a number of other factors. However, for heavily loaded hoisting machines, the main technical obstacle to safe operation is metal fatigue The results of a statistical analysis of defects detected by expert diagnosis of self-propelled boom-type cranes that have fulfilled the standard operating period are presented. The largest number of defects is associated with the destruction and wear of structural elements, the occurrence of fatigue cracks and the violation of the operating conditions of the equipment. The greatest number of defects is found in the hydraulic system of cranes, elements of the cable-block system, less often in metal construction. To conduct a risk analysis of self-propelled jib cranes in conditions of insufficient information, a methodology for expert assessments is proposed. It allows you to evaluate the impact of potential defects of self-propelled jib cranes on the amount of economic damage to the crane itself and the transported load and on the magnitude of the traumatic impact on humans. Defects and damage to the metal structures of the cranes discovered during the examinations are the result of the following combination of reasons: low quality of the metal (mild steel); unsatisfactory design; unsatisfactory quality of manufacture and installation of individual elements; environmental aggressiveness; operation of cranes in an unintended mode, poor maintenance and repair Keywords: safety, propelled jib crane, defect, expert assessment, risk analysis, diagnosis.

Analysis of Calculation Methods for Life Cycle Greenhouse Gas Emissions for Road Sector

2017 ◽  
Author(s):  
Viktoras Vorobjovas ◽  
Algirdas Motiejunas ◽  
Tomas Ratkevicius ◽  
Alvydas Zagorskis ◽  
Vaidotas Danila
Keyword(s):  
Climate Change ◽  
Life Cycle ◽  
Greenhouse Gas ◽  
Carbon Footprint ◽  
Ghg Emissions ◽  
Road Construction ◽  
Evaluation Methods ◽  
The Road ◽  
Construction Methods ◽  
The Impact

Climate change is one of the main nowadays problem in the world. The politics and strategies for climate change and tools for reduction of greenhouse gas (GHG) emissions and green technologies are created and implemented. Mainly it is focused on energy, transport and construction sectors, which are related and plays a significant role in the roads life cycle. Most of the carbon footprint emissions are generated by transport. The remaining emissions are generated during the road life cycle. Therefore, European and other countries use methods to calculate GHG emissions and evaluate the impact of road construction methods and technologies on the environment. Software tools for calculation GHG emissions are complicated, and it is not entirely clear what GHG emission amounts generate during different stages of road life cycle. Thus, the precision of the obtained results are often dependent on the sources and quantities of data, assumptions, and hypothesis. The use of more accurate and efficient calculation-evaluation methods could let to determine in which stages of road life cycle the largest carbon footprint emissions are generated, what advanced road construction methods and technologies could be used. Also, the road service life could be extended, the consumption of raw materials, repair, and maintenance costs could be reduced. Therefore the time-savings could be improved, and the impact on the environment could be reduced using these GHG calculation-evaluation methods.

scholarly journals Asphalt Concrete Mixtures: Requirements with regard to Life Cycle Assessment

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Jan Mikolaj ◽  
Frantisek Schlosser ◽  
Lubos Remek ◽  
Aurelia Chytcakova
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Service Life ◽  
Asphalt Concrete ◽  
Asphalt Mixture ◽  
Mixing Ratios ◽  
Construction Methods ◽  
And Performance ◽  
Term Performance ◽  
Whole Life Cycle

Design of asphalt concrete, required properties of constituent materials and their mixing ratios, is of tremendous significance and should be implemented with consideration given to the whole life cycle of those materials and the final construction. Conformity with requirements for long term performance of embedded materials is the general objective of the Life Cycle Assessment (LCA). Therefore, within the assessment, material properties need to be evaluated with consideration given to the whole service life—from the point of embedding in the construction until their disposal or recycling. The evaluation focuses on verification of conformity with criteria set for these materials and should guarantee serviceability and performance during their whole service life. Recycling and reuse of asphalt concrete should be preferred over disposal of the material. This paper presents methodology for LCA of asphalt concrete. It was created to ensure not only applicability of the materials in the initial stage, at the point of their embedding, but their suitability in terms of normatively prescribed service performance of the final construction. Methods described and results are presented in a case study for asphalt mixture AC 11; I design.

scholarly journals M. W. Tofique, A. Löf, C. Millward, Z. Günther. Testing and calculation of impact fatigue strength of Flap-X and SS 716 flapper valve steel grades / trans from Engl. M. A. Fedorova

2021 ◽  
Vol 5 (3) ◽  
pp. 63-74
Author(s):  
M. A. Fedorova ◽  
Keyword(s):  
Fatigue Strength ◽  
Service Life ◽  
Fluid Pressure ◽  
Test Method ◽  
Impact Fatigue ◽  
Staircase Test ◽  
Reliable Service ◽  
Steel Grades ◽  
Valve Steel ◽  
The Impact

During the operation of reciprocating compressors, the flapper valve opens and closes under fluid pressure and flow. As it closes, it strikes against the valve seat, generating stresses and noise. This cycle of loading produces bending and impact fatigue stresses in the reed. This load pattern is repeated billions of times during the service life of a compressor and it defines the service life and reliability. The goal of this study was to calculate the impact fatigue strength of the Flap-X and the SS 716 grades and, to provide the compressor manufacturers with the information they can use to specify a steel grade to be used in their compressors, for reliable service. Impact fatigue tests were conducted on a custom-built impact fatigue test rig that used air pulses to produce movement of the reed valves manufactured by a major European compressor manufacturer Nidec Global appliance GmbH, at a frequency of 315 Hz and pulse width of 2,2 milliseconds. The testing was conducted according to the staircase test method detailed in the International Standard SS-ISO 12107:2012. The impact fatigue strength of the Flap-X and SS 716 steel valves was calculated in terms of the impact velocity according to the modified staircase test method in the standard. The test results and their statistical analysis showed that the impact fatigue strength of the Flap-X grade was higher compared to the SS 716 grade. The calculation and testing of the impact fatigue strength of the flapper valve steel grades could help the compressor designers to select the optimum material for their compressor designs, to provide reliable service. The higher impact fatigue strength of the Flap-X grade, lower failure rate and longer impact fatigue life will allow the compressor manufacturers to design thinner valves, as Flap-X can sustain higher impact fatigue stresses reliably for longer time and, at the same time help reduce noise, as thinner valves produce less noise for a given pressure and frequency.

scholarly journals Impact of Service Life on the Environmental Performance of Buildings

Buildings ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 9 ◽  
Author(s):  
Shahana Janjua ◽  
Prabir Sarker ◽  
Wahidul Biswas
Keyword(s):  
Life Cycle ◽  
Service Life ◽  
Environmental Performance ◽  
Energy Demand ◽  
Cumulative Energy ◽  
Cumulative Energy Demand ◽  
Building Components ◽  
Environmental Performance Assessment ◽  
Increasing Demand ◽  
The Impact

The environmental performance assessment of the building and construction sector has been in discussion due to the increasing demand of facilities and its impact on the environment. The life cycle studies carried out over the last decade have mostly used an approximate life span of a building without considering the building component replacement requirements and their service life. This limitation results in unreliable outcomes and a huge volume of materials going to landfill. This study was performed to develop a relationship between the service life of a building and building components, and their impact on environmental performance. Twelve building combinations were modelled by considering two types of roof frames, two types of wall and three types of footings. A reference building of a 50-year service life was used in comparisons. Firstly, the service life of the building and building components and the replacement intervals of building components during active service life were estimated. The environmental life cycle assessment (ELCA) was carried out for all the buildings and results are presented on a yearly basis in order to study the impact of service life. The region-specific impact categories of cumulative energy demand, greenhouse gas emissions, water consumption and land use are used to assess the environmental performance of buildings. The analysis shows that the environmental performance of buildings is affected by the service life of a building and the replacement intervals of building components.

scholarly journals Environmental and Economic Prioritization of Building Energy Refurbishment Strategies with Life-Cycle Approach

2020 ◽  
Vol 12 (9) ◽  
pp. 3914
Author(s):  
Xabat Oregi ◽  
Rufino Javier Hernández ◽  
Patxi Hernandez
Keyword(s):  
Life Cycle ◽  
Service Life ◽  
Energy Use ◽  
Residential Building ◽  
Net Energy ◽  
Life Cycle Approach ◽  
Life Cycle Assessment Methodology ◽  
Impact Indicator ◽  
Sensitivity Assessment ◽  
The Impact

An increasing number of studies apply life-cycle assessment methodology to assess the impact of a new building or to prioritize between different building refurbishment strategies. Among the different hypotheses to consider during the application of this methodology, the selection of the impact indicator is critical, as this choice will completely change the interpretation of the results. This article proposes applying four indicators that allow analysing the results of a refurbishment project of a residential building with the life-cycle approach: non-renewable primary energy use reduction (NRPER), net energy ratio (NER), internal rate of return (IRR), and life-cycle payback (LC-PB). The combination of environmental and economic indicators when evaluating the results has allowed to prioritize among the different strategies defined for this case study. Furthermore, an extensive sensitivity assessment reflects the high uncertainty of some of the parameters and their high influence on the final results. To this end, new hypotheses related to the following parameters have been considered: reference service life of the building, estimated service life of material, operational energy use, conversion factor, energy price, and inflation rate. The results show that the NRPE use reduction value could vary up to −44%. The variation of the other indicators is also very relevant, reaching variation rates such as 100% in the NER, 450% in the IRR, and 300% in the LC-PB. Finally, the results allow to define the type of input or hypothesis that influences each indicator the most, which is relevant when calibrating the prioritization process for the refurbishment strategy.

Service Performance of HPSFRC Suitable for Super-High Vertical Pumping

2011 ◽  
Vol 374-377 ◽  
pp. 1891-1898
Author(s):  
Jin Yang Jiang ◽  
Wei Sun ◽  
Jing Wang
Keyword(s):  
Service Life ◽  
Crack Resistance ◽  
Steel Fiber ◽  
Fatigue Loading ◽  
Assessment Method ◽  
Fiber Reinforced Concrete ◽  
Life Assessment ◽  
Small Scale ◽  
Concrete Durability ◽  
Steel Fiber Reinforced Concrete

A type of small-scale fibers with dumbbells on two ends and notches in the middle was first designed to improve the workability and crack resistance of fresh high performance steel fiber reinforced concrete (HPSFRC). By using the fiber, the HPSFRC was continuously pumped to 306 meter high Sutong bridge tower. To ensure crack resistance of HPSFRC, tests concerning both non-loaded crack and structural crack were systematically performed, respectively. Then, the mechanisms behind the macro-behaviors were explored. Finally, life assessment method of HPSFRC that focused on the fatigue loading coupled with chloride and carbonation environment was presented by considering the effects of different fatigue degree on concrete durability. The results demonstrate that the steel fiber has the remarkable ability to restrain shrinkage and resist structural crack. It was also shown that the small-scale steel fiber can greatly improve the fracture toughness and fatigue property. In addition, the increased degree of damage due to fatigue loading would shorten the service life of concrete and the service life of HPSFRC under the multi-damage of fatigue loading and environmental loading would be longer than that of plain concrete.

scholarly journals Economic and Environmental Assessment of Plastic Waste Pyrolysis Products and Biofuels as Substitutes for Fossil-Based Fuels

2021 ◽  
Vol 9 ◽  
Author(s):  
Adrián Pacheco-López ◽  
Fabian Lechtenberg ◽  
Ana Somoza-Tornos ◽  
Moisès Graells ◽  
Antonio Espuña
Keyword(s):  
Life Cycle ◽  
Human Health ◽  
Environmental Assessment ◽  
Resource Scarcity ◽  
Plastic Waste ◽  
Production Costs ◽  
Superior Performance ◽  
Fuel Quality ◽  
Impact Reduction ◽  
The Impact

The global economy is shifting toward more sustainable sources of energy. The transportation sector is a remarkable example of this fact, where biofuels have emerged as promising alternatives to traditional fossil fuels. This work presents a techno-economic and environmental assessment of existing liquid fuels in hard-to-decarbonize sectors and their emerging renewable substitutes. The comparison focuses on fossil-based, biomass-derived, and plastic waste-sourced fuel alternatives that can be used in spark-ignition (gasoline) and compression-ignition (diesel) engines. Results for diesel substitutes prove the superior performance of plastic waste pyrolysis oil in terms of production cost reduction (−25% compared to diesel) and “well-to-tank” life cycle impact reduction (−54% human health, −40% ecosystems, −98% resources). Consequently, research and development toward the conversion of plastic waste into fuels should be extended to make the technology more accessible and robust in terms of fuel quality. On the contrary, the results for gasoline alternatives are not as conclusive: bioethanol and ethanol from plastic pyrolysis have a considerably lower impact on resource scarcity than gasoline (−80% and −35% respectively) and higher on the other two life cycle endpoint categories, but they have higher production costs compared to gasoline (+57% and +130% respectively). While blends of gasoline with pyrolysis-sourced ethanol can reduce the impact on human health and ecosystems, blends with bioethanol have a lower impact on resource scarcity and increase economic profitability. This allows fuel providers to offer tradeoff solutions in the form of blends based on their priorities.

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