A Risk Based Approach for Proactive Asset Management of Sewer Structural Conditions in England and Wales

The aim of this research is to create a risk based framework to prioritise proactive investment for sewers in England and Wales. This research proposes a sewer deterioration model that will enhance and not replace the industry’s business as usual process and it also recommends how standard sewer assessment reports can be better utilised to inform business decisions. The methodology used to complete this research project is a mixture of qualitative and quantitative approaches to analyse a total length of 24,252 km which represents 703,156 records of historic sewer structural condition inspection data. This was used to build an improved deterioration model. Proactive investment (future condition prediction) assessments have been made within Thames Water and other wastewater utilities in the UK. The approaches are reviewed, compared, limitation identified and a robust approach was defined, devising means to mitigate the limitations identified. Existing approaches within and outside the industry to assess sewer condition and model sewer deterioration for risk management was reviewed. Data analytical software such as MATLAB and Tibco Spotfire were used to create an intuitive risk framework that will aid sewer investment decision making. An improved deterioration model and inspection frequencies for sewers were developed as a premise for proactive investment. This deterioration model and the inspection frequencies were then used to create a risk based framework to help set proactive priorities for sewer management. This would enable sewerage asset owners with large kilometres of sewers to manage the sewerage system more proactively before they reach a critical point and reduce the reliance on industry expert judgement and further surveys. The improved deterioration model and inspection frequencies provided in this research would enable sewer asset managers to determine the most cost-effective time to invest in repairs or replacement. Also, a plausible and reliable validation that was provided would give a high level of confidence in the risk based framework

Hybridní tkané struktury

Tato disertační práce poskytuje podrobnější informace o vlastnostech čedičových vláken vedle běžně používaných vláken, a to pro návrh a vývoj hybridních tkaných textilií určených pro výrobu kompozitních materiálů, zejména betonu vyztuženého textilií (TRC). Zkoumány jsou různé kombinace čedičové hybridní tkaniny s ohledem na mechanické, tepelné, akustické, elektrické a jiné vlastnosti, přičemž vliv hybridizace a struktury tkaných textilií je studován detailněji. Mechanické vlastnosti jsou predikovány s použitím a strukturální modely korelovány s výsledky získanými z provedených experimentů. Čedičová vlákna jsou velmi perspektivním materiálem díky jejich ohnivzdornosti spojené s lávovým původem, vynikajícím mechanickým vlastnostem a relativně nízké ceně. Na druhou stranu, tato vlákna doposud nebyla podrobena rozsáhlejšímu průzkumu, protože je možno je považovat za relativně nový typ vlákna. V technických článcích je možno nalézt jen omezené množství údajů o jejich chování po zpracování, jež je spojeno se stárnutím materiálu. Disertační práce prozkoumává možnosti využití čedičových vláken v kombinaci s jinými typy přízí a následně také vliv hybridní tkané struktury na nosnost kompozitu a dobu jeho životnosti. V této studii je vyšetřeno nosné chování TRC kompozitu (kompozitní systém tvořený jemnozrnnou betonovou matricí a výztuží složenou z vysoce funkčních vláken zpracovaných do plošné textilie) při jednoosém namáhání tahem. Průzkum je zaměřen na výztužnou schopnost hybridní tkané struktury. Při začleňování textilní struktury do betonu je zřejmé, že veškeré příze nejsou impregnovány cementovou matricí kompletně, což vede k heterogenitě systému beton - příze přispívajícímu ke komplexní nosnosti a defektnímu chování TRC kompozitu. Hlavním cílem této práce je tedy průzkum hybridizačních efektů na nosné chování TRC kompozitu.This thesis conveys a better insight into characteristics of Basalt fibers specifically, alongside commonly used fibers to design and develop hybrid woven fabrics for TRC composite materials. Various combinations of basalt hybrid fabrics are investigated with respect to mechanical, thermal, acoustic, electrical and other functional properties. The influence of hybridization and structure of woven fabric is studied in detail. The tensile properties are predicted by using structural model and correlated to the results obtained through experiments. Basalt fibers are very promising materials due to their fire resistance related to magmatic origin, superior mechanical properties and relatively low cost. On the other hand, being a relatively new kind of fiber, they are still not studied extensively. There are very few indications in technical papers about their behavior after aging treatments. The current study investigates the possibility of using basalt with other types of yarns and consequently the effect of hybrid woven structure on load bearing capacity and durability. In the present work, the load-bearing behavior of Textile Reinforced Concrete (TRC), which is a composite of a fine-grained concrete matrix and a reinforcement of high-performance fibers processed to textiles, when exposed to uniaxial tensile loading was investigated. The investigations are focused on reinforcement of hybrid woven fabrics. When textile yarns are embedded in concrete, they are not entirely impregnated with cementitious matrix, which leads to associated heterogeneity of the concrete and the yarns to a complex load-bearing and failure behavior of the composite system. The main objective of the work is the investigation of hybridization effects in the load-bearing behavior of TRC

An economic evaluation on FRP for bridge construction in South African coastal areas

Fibre Reinforced Polymers (FRP) have been used for approximately 30 years as concrete strengthening materials in structural applications. This is primarily due to Steel Reinforced Concrete (SRC) being susceptible to the corrosion of reinforcing steel, especially in coastal environments. However, the use of FRP composites for bridge construction is faced with challenges. These challenges arise from uncertainties regarding the high material and initial construction costs. Additionally, there is limited research available on the costs involved when incorporating the fibres in bridge constriction. It then becomes critical to understand the life cycle costs of FRP in bridge construction. Furthermore, suitable economic and deterioration models can be used to predict these life cycle costs by employing a LCCA. The research aim was to investigate the economic viability of using FRP as reinforcing elements in bridge construction. This was done by conducting a life cycle cost analysis (LCCA) on two highway beam bridge superstructure designs: a SRC superstructure and a GFRP-RC superstructure to determine the preferred design, which was used to conclude on the economic viability of FRP in bridge construction. The deterministic approach to the LCCA was selected and the outcome was expressed in terms of Present Worth of Costs (PWOC). The initial construction costs were found to be the bulk, while the disposal costs were the least of the total LCC for both superstructure alternatives. Furthermore, initial construction costs of the SRC superstructure were found to be less than that of the GFRP-RC superstructure, by a margin of R 873 094. This was primarily due to the cost of E-glass reinforcement, approximately 2.1 to 2.9 times more expensive than the cost of steel reinforcement. Moreover, the cost of GFRP was seen to have decreased over the years. LCC savings were seen from the GFRP-RC superstructure over the SRC superstructure, by a margin of R4 627 830 in terms of maintenance costs. This was mainly due to the application of a corrosion inhibitor (concrete surface treatment) and the use of a cathodic protection system on the SRC bridge superstructure. Furthermore, the GFRP-RC superstructure was found to be the least cost-effective investment from approximately 34 years of a 75 year LCCA period. At the end of the analysis period, the SRC bridge superstructure was found to have cost savings of approximately R 753 921 in PWOC over the GFRP-RC superstructure. Furthermore, a sensitivity analysis of the various input costs and discount rates of the LCCA was also conducted. Initial construction costs were found to have the highest positive correlation on the outcome of the LCCA. The other costs and as well as the discount rate were all found to have an insignificant effect on the outcome of the LCCA. It was concluded that it was not economically viable to include FRP as reinforcing elements in bridge construction at the time. However, since the cost of FRP was seen to decrease over time, the inclusion of FRP rebars in bridge construction might be economically viable in the future

Composites for hydraulic structures: a review

Composites for hydraulic structures: a review Composites have evolved over the years and are making major in-roads into the marine, aviation and other industries where corrosions and self-weight are the major impediments to advancing the state-of-the-art. Civil Works engineers have been reluctant to make use of these composite advantages, partially because of the absence of well documented success stories, accepted design and construction practices or specifications, and limited understanding of composites, higher initial costs and others. A few navigational structures using FRP composites have been designed, manufactured and installed in the United States of America and Netherlands, recently. US Army Corps of Engineers is embarking on higher volume applications of composites for navigational structures. This report is aimed at summarizing the state of the art of fiber reinforced polymer (FRP) composites for hydraulic structures including design, construction, evaluation and repair. After a brief review of history and introduction of fundamentals of composites, their manufacturing techniques, properties, and recent field applications are presented, including FRP rebar for bridge decks, other highway and railway structures, gratings, underground storage tank, pavement, sheet and pipe piling, FRP wraps, moveable bridges, utility poles, etc. Focus is placed on applications of composites in waterfront, marine, navigational structures including lock doors, gates, and protection systems. Design of hydraulic composite structures is presented for the cases available, such as design of FRP recess panel, Wicket Gates, Miter Gates, FRP slides and repair of corroded steel piles. This report also reviews engineering science issues such as fracture and fatigue, durability, creep and relaxation, UV degradation, impact resistance, and fire performance. The report concludes with summary remarks and recommendations after a discussion on operation and maintenance guidance including nondestructive evaluation inspection techniques. Intention is to provide up to date information on composite design, manufacturing and evaluation methodologies that are applicable for fabrication and maintenance of navigational structures. This report is a living document with advances taking place with time as waterborne transport infrastructure community makes progress with FRP systems. This report is expected to be useful for those decision-makers in government, consultants, designers, contractors, maintenance and rehab engineers whose focus is to minimize traffic interruptions while maximizing cost effectiveness

International Conference on Civil Infrastructure and Construction (CIC 2020)

This is the proceedings of the CIC 2020 Conference, which was held under the patronage of His Excellency Sheikh Khalid bin Khalifa bin Abdulaziz Al Thani in Doha, Qatar from 2 to 5 February 2020. The goal of the conference was to provide a platform to discuss next-generation infrastructure and its construction among key players such as researchers, industry professionals and leaders, local government agencies, clients, construction contractors and policymakers. The conference gathered industry and academia to disseminate their research and field experiences in multiple areas of civil engineering. It was also a unique opportunity for companies and organizations to show the most recent advances in the field of civil infrastructure and construction. The conference covered a wide range of timely topics that address the needs of the construction industry all over the world and particularly in Qatar. All papers were peer reviewed by experts in their field and edited for publication. The conference accepted a total number of 127 papers submitted by authors from five different continents under the following four themes: Theme 1: Construction Management and Process Theme 2: Materials and Transportation Engineering Theme 3: Geotechnical, Environmental, and Geo-environmental Engineering Theme 4: Sustainability, Renovation, and Monitoring of Civil InfrastructureThe list of the Sponsors are listed at page 1

The Use of Recycled Materials to Promote Pavement Sustainability Performance

This Special Issue focuses on recycled materials to promote pavement sustainability. It covers the use of construction and demolition waste (reclaimed asphalt pavement, recycled concrete aggregate and glass) and industrial waste (plastic and slag). The application of recycled materials concerns bituminous mixtures, concrete mixtures, and non-traditional interlocking blocks or cobbles

Risk-Based Decision-Making Modeling for Wastewater Pipes

The dissertation research work described here has three primary objectives under risk-based decision making. (1) The development of a comprehensive sewer pipe condition rating model that incorporates many environmental, structural, and hydraulic parameters. (2) The development of a sewer pipe deterioration model used to predict future overall condition states of the pipe, as well as determining the probability of failure at any given age of the pipe. (3) The development of a comprehensive consequence of failure model that assesses the consequence of sewer pipe failure using economic, social, and environmental cost factors. The Pipeline Assessment and Certification Program (PACP) was developed by the National Association of Sewer Service Companies, the industry-accepted protocol for condition rating sewer pipes in the US. The PACP method relies exclusively on visual inspections performed using Closed-Circuit Television (CCTV), where existing structural and operation and maintenance (O&M) defects are observed by certified operators. A limitation of the PACP method is that it does not use pipe characteristics, depth, soil type, surface conditions, pipe criticality, capacity, the distribution of structural defects, or history of preventative maintenance to determine the condition rating of the sewer pipe segment. Therefore, a comprehensive rating model with pipe characteristics, external characteristics, and hydraulic characteristics was developed. The calculating of a comprehensive rating is an entirely manual process. Therefore, this research work addresses this limitation of Analytical Hierarchy Process (AHP) and suggests AHP is not a suitable method to calculate comprehensive rating. Develops a faster calculation of a comprehensive rating model using and K-NN that incorporates pipe characteristics, environmental characteristics, and information about PACP structural score and PACP O&M score in hydraulic factors. Factors such as pipe age, pipe material, diameter, shape, depth, soil type, loading, carried waste, seismic zone, PACP structural score, and PACP O&M score are used. Our proposed model is applied to the data received from the City of Shreveport, LA, which is currently under a Federal Consent Decree. The results of a comprehensive rating model showed a below-average validity percentage because linear regression assumes a linear relationship between the input and output variables. Still, the relationship between response and the predictor is not linear for AHP to prove AHP is not a suitable method and satisfactory results for K-NN. As part of decision-making, for capital improvement planning and budgeting, the capacity to predict future sewer pipe conditions and potential breakdowns is essential. In contrast to the often-used Discrete Time Markov Chain approaches in the literature, the deterioration model created here uses a Continuous Time Markov Chain method to calculate the likelihood that a pipe will change from a better to a worse condition at given age. The consequence of the pipe\u27s failure is established to ascertain the risk of failure and to create a comprehensive framework for risk-based decision-making. To estimate the impact of the asset\u27s failure, the established consequence of failure model considers a significant number of economic, social, and environmental cost elements. For budgeting future capital projects and improvements, the CTMC model and failure consequences for sewers are useful