A large pilot-scale free water surface (FWS) constructed wetland polishing effluent from an annual (spring) discharge municipal lagoon was operated for ten years followed by eleven years of dormancy and then restarted with an increase in operating depth. No significant effect of system aging was observed on Biological Oxygen Demand (BOD), total phosphorus (TP), and soluble reactive phosphorus (SRP) removal efficiencies, although internal TP water column concentrations in the first wetland and pond cells increased with time due to resuspension of accumulated sediments. Nitrate and ammonium removal efficiencies were higher during the start-up period due to plant establishment, while organic nitrogen and nitrate removal efficiencies increased during the restart period, likely due to a combination of the increased operating depth and accumulated sediments. No seasonal temperature effect was observed for nitrate or BOD removal efficiency, however, TP removal efficiencies increased with increasing influent concentrations due to seasonal algae growth. TSS removal efficiency increased significantly during the restart period, most likely due to an increase in the operating depth. Phosphorus was found to be mostly stored in the soil, followed by sediment and plants, while nitrogen was found to be stored more in plants, followed by soil and sediment. The wetland system was shown to be effective at the long-term removal of organic matter (BOD5 < 10 mg/L) and TP (87% average removal efficiency), while TSS removal efficiency increased to 97% with an increase in operating depth from 25 to 50 cm.

Performance based contracting in the transportation arena is a rather recently implemented concept which has a few number of applications in the United States up to date. Nonetheless, the US Department of Transportation has vigorously promoted (by issuing memorandums to be distributed to the Highway Agencies and State Departments of Transportation) the conversion of traditional contracts to performance based contracts to reach a goal of 80% of the service contracts and actions being performance based by the end of fiscal year 2004 (Tomanelli 2003.) Virginia Department of Transportation (VDOT) has been one of the first state agencies that took the initiative of using a performance based contract for the maintenance of a portion of its interstate highway system. This initiative resulted in the establishment of the 'Comprehensive Agreement for Interstate Highway Asset Management Services' between VDOT and a private contractor in 1996 which resulted in the privatization of highway maintenance services. One of the important aspects of this contract related to this research is that it does not encompass any warranty clauses. In other words, the contractor does not provide any warranty to the VDOT for the services it is obligated to undertake. The contract is mute in this subject, making the contractor incur no liability for the underperformance of the maintenance activities. According to this research, this might lead to some cases which VDOT would not be willing to encounter. Just like performance based contracting, the use of warranties in highway contracts in the United States is a quite new concept which mainly dates back to 1995. There are different views possessed by different parties about the possible outcomes of implementing warranties in highway contracts. Nonetheless, this research proposes that the incorporation of warranty clauses into the VDOT issued performance based road maintenance contracts is vital to ensure the quality and durability of the work after the project completion. According to this research, warranty clauses, if developed carefully, give the contractor the motivation to implement superior maintenance practices to improve the overall conditions of the assets during the contract period. This is done in order to lengthen the life of each asset item and achieve the long term performance. Ultimately, the incorporation of warranty clauses is believed to reduce the risk imposed upon VDOT. Within the context of the discussion presented above, this research first illustrates that the complete satisfaction of one of the parties (VDOT) may be in question due to the absence of the warranty clauses within the contract, then lists and explores the benefits that would/may be gained by the incorporation of warranty clauses into the contract, and finally develops a warranty clause template and proposes it to be used in the future performance based road maintenance contracts issued by VDOT. At the bottom line, this study aspires to help the party in question (VDOT) to reduce the risk imposed upon it and to improve the future performance based road maintenance contracts it will issue. This research uses the VDOT contract as a baseline to define the problem and to propose a solution (i.e. the developed warranty clause template) for that. Nonetheless, some of the principles and approaches used during the development of the warranty clause template can also be referred to for the development of warranty clauses for the performance based road maintenance contracts issued by the other state DOTs. / Master of Science

The purpose of this research was to investigate the effectiveness and durability of GFRP bars as reinforcement for concrete decks. Today's rapid bridge deck deterioration is calling for a replacement for steel reinforcement. The advantages of GFRP such as its high tensile strength, light weight, and resistance to corrosion make it an attractive alternative to steel. The first objective of this research was to perform live load testing on a bridge deck reinforced with GFRP in one span and steel in the other. The results were compared to the findings from the initial testing performed one year earlier. The strains and deflections of the bridge deck were recorded and the two spans compared. Transverse stresses in the GFRP bars, girder distribution factors, and dynamic load allowances were calculated for both spans. From the live load tests, it was concluded that the GFRP-reinforced span results were within design parameters. The only concern was the increased impact factor values. The second objective was to perform live load tests on a slab reinforced with GFRP installed at a weigh station. Two live load tests were performed approximately five months apart. Peak strains in the GFRP and steel bars were recorded and compared. The peak stresses had increased over time but were within design allowable stress limits. The third objective of this research was to investigate the long term behavior and durability of the GFRP reinforcing bars cast in a concrete deck. The strain gauges, vibrating wire gauges, and thermocouples in the bridge deck were monitored for approximately one year using a permanent data acquisition system. Daily, monthly, and long term fluctuations in temperature and stresses were examined. It was concluded that the vibrating wire gauges were more reliable than the electrical resistance strain gauges. It was further observed that the main influence over strain changes was temperature fluctuations. / Master of Science

Many failures of external walls made of porous buildingmaterials are caused by excessive moisture content,particularly after driving rain and under long duration ofmoist conditions. Lack of sufficient protection againstexposure conditions is one of the reasons for external wallsprematurely demonstrating failures, i.e. properties andperformance above/below critical levels. Silicon-based waterrepellants are increasingly used in order to improve theperformance of both old and new buildings. Water repellants areexpected to prolong the service life and improve the durabilityof wall components by preventing or minimising water ingressinto the structure and thus delaying the deteriorating effectsof the atmosphere. To date, various kinds of water repellantshave been developed. However, only limited research has beencarried out, particularly on the long-term field exposuretesting. Existing research is mainly focused on the performanceof surface treatments of concrete structures and the protectionof historical buildings built of stone, brick and wood, and isprimarily based on short-term laboratory testing. The aim ofthis research work is to study the long-term performance,degradation processes and ageing characteristics of renderedautoclaved aerated concrete (AAC) with and without waterrepellants. Investigations are carried out by physical andchemical analysis of fresh samples, samples naturally weatheredby long-term field exposure and samples artificially aged byshort-term accelerated laboratory tests. Two differentapplication of water repellants are employed: impregnation ofrendering surface with an aqueous product and as additive inpowder form mixed into the fresh rendering mortar. Continuousmoisture and temperature monitoring of naturally exposed testsamples are also included in the study. Wetcorr sensors andresistance-type nail electrodes are used to measure the surfacemoisture and the moisture content in the material,respectively. This thesis describes the experimental set-upand presents the results from site monitoring and laboratorytests of unexposed, naturally and artificially exposed samples(freeze-thaw and UV+water). The results from the continuousmoisture measurements are compared with the results obtainedfrom the full-scale test cabin built within the EUREKA-projectE 2116 DurAAC. The test cabin has the same basic measurementinstruments for continuous monitoring of moisture andtemperature. An attempt has been made to develop methods forlong-term performance assessment of water repellants to be usedin service life prediction. The combination of data obtainedfrom the field measurements with data obtained from thelaboratory tests and analysis may also meet practical needs ofthe end-users.

In post-tensioned (PT) bridges, prestressing steel tendons are the major load carrying components. These tendons consist of strands, ducts, and cementitious grout that fill the interstitial space between the strands and ducts. However, inspections on PT bridges have reported the presence of voids, moisture, and chlorides inside grouted ducts as the major cause of accelerated corrosion of strands. Corrosion of the strands has resulted in PT bridge failures in Europe and tendon failures in the United States. As most of the PT bridges have high importance measures and the consequences of failure are significant, it is important to maintain high levels of safety and serviceability for these bridges. To meet this goal, bridge management authorities are in dire need of tools to quantify the long-term performance of these bridges. Time-variant structural reliability models can be useful tools to quantify the long-term performance of PT bridges. This doctoral dissertation presents the following results obtained from a comprehensive experimental and analytical program on the performance of PT bridges. 1) Electrochemical characteristics of PT systems 2) Probabilistic models for tension capacity of PT strands and wires exposed to various void and environmental conditions 3) Time-variant structural reliability models (based on bending moment and stress limit states) for PT bridges 4) Time-variant strength and service reliabilities of a typical PT bridge experiencing HS20 and HL93 loading conditions and different exposure conditions for a period of 75 years The experimental program included exposure of strand specimens to wet-dry and continuous-atmospheric conditions. These strand specimens were fabricated to mimic void and/or grout-air-strand (GAS) conditions inside the tendons. It was found that the GAS interface plays a major role in strand corrosion. The GAS interfaces that are typically located in the anchorage zones of harped PT girders or vertical PT columns can cause aggressive strand corrosion. At these locations, if voids are present and the environment is relatively dry, then limited corrosion of the strands occurs. However, if the presence of high relative humidity or uncontaminated and chloride-contaminated water exists at these interfaces, then corrosion activity can be high. The strands were exposed for a period of 12, 16, and 21 months, after which the remaining tension capacity was determined. The analytical program included the development of probabilistic strand capacity models (based on the experimental data) and the structural reliability models. The timevariant tension capacity predicted using the developed probabilistic models were reasonably consistent with the tendon failures observed in PT bridges in Florida and Virginia. The strength reliability model was developed based on the moment capacity and demand at midspan. Service reliability model was developed based on the allowable and applied stresses at midspan. Using these models, the time-variant strength and service reliabilities of a typical PT bridge were determined based on a set of pre-defined constant and random parameters representing void, material, exposure, prestress, structural loading, and other conditions. The strength and service reliabilities of PT bridges exposed to aggressive environmental conditions can drop below the recommended values at relatively young ages. In addition, under similar conditions the service reliability drops at a faster rate than the strength reliability.

<p>Many failures of external walls made of porous buildingmaterials are caused by excessive moisture content,particularly after driving rain and under long duration ofmoist conditions. Lack of sufficient protection againstexposure conditions is one of the reasons for external wallsprematurely demonstrating failures, i.e. properties andperformance above/below critical levels. Silicon-based waterrepellants are increasingly used in order to improve theperformance of both old and new buildings. Water repellants areexpected to prolong the service life and improve the durabilityof wall components by preventing or minimising water ingressinto the structure and thus delaying the deteriorating effectsof the atmosphere. To date, various kinds of water repellantshave been developed. However, only limited research has beencarried out, particularly on the long-term field exposuretesting. Existing research is mainly focused on the performanceof surface treatments of concrete structures and the protectionof historical buildings built of stone, brick and wood, and isprimarily based on short-term laboratory testing. The aim ofthis research work is to study the long-term performance,degradation processes and ageing characteristics of renderedautoclaved aerated concrete (AAC) with and without waterrepellants. Investigations are carried out by physical andchemical analysis of fresh samples, samples naturally weatheredby long-term field exposure and samples artificially aged byshort-term accelerated laboratory tests. Two differentapplication of water repellants are employed: impregnation ofrendering surface with an aqueous product and as additive inpowder form mixed into the fresh rendering mortar. Continuousmoisture and temperature monitoring of naturally exposed testsamples are also included in the study. Wetcorr sensors andresistance-type nail electrodes are used to measure the surfacemoisture and the moisture content in the material,respectively. This thesis describes the experimental set-upand presents the results from site monitoring and laboratorytests of unexposed, naturally and artificially exposed samples(freeze-thaw and UV+water). The results from the continuousmoisture measurements are compared with the results obtainedfrom the full-scale test cabin built within the EUREKA-projectE 2116 DurAAC. The test cabin has the same basic measurementinstruments for continuous monitoring of moisture andtemperature. An attempt has been made to develop methods forlong-term performance assessment of water repellants to be usedin service life prediction. The combination of data obtainedfrom the field measurements with data obtained from thelaboratory tests and analysis may also meet practical needs ofthe end-users.</p>

Continuously reinforced concrete pavement (CRCP) is a portland cement concrete (PCC) pavement structure with a continuous longitudinal steel layout. CRCP is forming a major portion of PCC roadway systems in the state of Texas due to its low life cycle cost, ease of maintenance, and durable nature. While the overall performance of CRCP is proven to be excellent, some performance problems are still found as a form of distresses such as punchout and spalling. The current pavement design guide states that these distresses are closely related with the early-age behavior characteristics of CRCP, and various measures are underway to develop to improve the long-term performance of CRCP in terms of initial material design and use, structural design, and quality control. Understanding the current issues that pavement engineers and researchers face, the primary objective of this dissertation research focuses on sound understanding of the early-age structural behavior characteristics of CRCP and its effect on the long-term performance to provide reliable design and analysis criteria for CRCP. To achieve this main objective, characterizing the early-age structural response in CRCP was a core task of this study. For this purpose, a zero-stress temperature (ZST), one of the design and construction variables considered to have most significant effects on CRCP behavior and performance, was evaluated. As a beginning point of the entire framework, a series of field experiments were conducted in four new PCC pavement construction projects in the state of Texas to evaluate the actual structural response in early-age CRCP since a laboratory experiment would have a critical limitation in simulating the restraint conditions that exist in actual CRCP. To expand this core task to various parametric categories, a computer-aided parametric simulation was performed using valid numerical models. Based on data sets obtained from the parametric investigation, a statistical model to quantify the early-age structural response of CRCP was proposed to implement in codes of practice and pavement design guides. A secondary task was to identify a correlation between the early-age structural response and the long-term performance of CRCP structures. Since the experimental and analytical investigations tended to provide quite localized information for the time-dependent behavior of CRCP, the overall performance of CRCP could not be properly identified solely based on those results. To overcome this limitation, extensive field condition surveys were performed in seven different old CRCP sections with known material and early-age temperature history to find the implications of early-age behavior characteristics on the long-term performance of CRCP from a macroscopic point of view. It is expected that this research effort will provide pavement engineers and researchers with useful information to understand the actual time-dependent behavior of CRCP and a solid foundation to improve the sustainability of CRCP structures. / text

Polymer pipes, typically high density polyethylene (HDPE), can be pulled-into-place, avoiding traditional cut-and-cover construction, using pipe bursting and horizontal directional drilling (HDD) pipe installation techniques. Of particular interest, are the ground displacements, induced by cavity expansion, associated with these techniques and the strains that develop in existing pipes in response to these displacements. Further, the axial stress-strain response of the new HDPE pipe during and after the cyclic pulling force history required to pull the pipe into place is of interest. Surface displacements and strains in an adjacent polyvinyl chloride (PVC) pipe induced by static pipe bursting were measured during the replacement of a new unreinforced concrete pipe. For the pipe bursting geometry tested, the maximum vertical surface displacement measured at the ground surface was 6 mm, while the distribution of vertical surface displacements extended no more than 2 m on either side of the centreline. The maximum longitudinal strain measured in the PVC pipe was less than 0.1% and its vertical diameter decreased by only 0.5%, suggesting that pipe bursting did not jeopardize the long-term performance of the water pipe tested. In addition, results from identical stress relaxation and creep tests performed on whole pipe samples and coupons trimmed from a pipe wall were compared, and these demonstrated that the coupons exhibited higher modulus than the pipe samples. Therefore, isolated pipe samples, as opposed to coupons, were tested to quantify the stress-strain response of HDPE pipe during the simulated installation, strain recovery, and axial restraint stages of HDD. Axial strains were found to progressively accumulate when an HDPE pipe sample was subjected to the cyclic stress history used to simulate an HDD installation. It was shown that existing linear and nonlinear viscoelastic models can serve as predictive design tools for estimating the cyclic strain history of HDPE pipe during installation. For the specific conditions examined, the tensile axial stresses redeveloped in the pipe samples, once restrained, were not large enough to lead to long-term stress conditions conducive to slow crack growth even when the short-term performance limits were exceeded by a factor of 1.5. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2009-04-01 18:19:24.434

Cette thèse est composée de trois essais qui étudient le déroulement des introductions en bourse. Dans le premier essai, nous examinons l’effet de la séparation propriété-contrôle sur la performance des offres publiques initiales (IPO) à long terme en France. En utilisant un échantillon de 351 entreprises françaises introduites en bourse sur la période 1997-2011, nous constatons que la séparation entre les droits de vote et les droits de propriété des actionnaires majoritaires est négativement associée à la performance à long terme des introductions en bourse. Cette constatation indique que les IPO ayant une structure de propriété dispersée sont moins performantes que les autres entreprises au cours de la période allant de 1 à 5 ans suivant l'offre initiale. Cette séparation incite les actionnaires dominants à retirer des avantages privés de contrôle au détriment des actionnaires minoritaires.Dans le deuxième essai, nous examinons le rôle des clauses de lock-up sur la précision des prévisions de résultat publiées dans le prospectus d'introduction en bourse. En utilisant un échantillon de 303 prévisions des entreprises françaises introduites en bourse entre 1997 et 2013, nous apportons la preuve que les introductions en bourse ayant plus d'actions à détenir, ainsi que celles qui choisissent des périodes de lock-up plus longues, sont plus susceptibles de divulguer des prévisions de résultats conservatrices et précises. Ces résultats sont robustes à un certain nombre de tests de sensibilité.Dans le troisième essai, nous étudions l'impact de la localisation géographique sur la sous-évaluation à court terme des introductions en bourse françaises. Les résultats montrent que les entreprises situées à proximité du centre financier parisien sont moins sous-estimées que les entreprises distantes. Ces résultats fournissent un support empirique à l'argument selon lequel l'incertitude sur la valeur des IPO augmente proportionnellement à la distance de Paris. En d'autres termes, la proximité géographique améliore la qualité des informations collectées sur les entreprises, ce qui réduit leurs coûts d'introduction en bourse et diminue le niveau des rendements initiaux. / This dissertation consists of three essays. In the first essay, we investigate whether the control-ownership divergence can explain IPO long-run performance in France. Using data from a sample of 351 French IPOs during 1997-2011, we find that the separation between ownership and control rights of the largest shareholder is negatively associated with long-term performance of French IPOs. This finding indicates that IPOs with disproportional ownership structure underperform other firms in the one- to five-year period following the initial offering. Such separation induces controlling shareholders to extract private benefits of control to the detriment of minority shareholders.In the second essay, we examine the effect of lockup agreements on management earnings forecasts in initial public offering (IPO) prospectuses. Using a sample of 303 forecasts of French firms that went public over the period 1997–2013, we find that IPOs with lockup clauses are more likely to disclose conservative profit forecasts. Moreover, we provide evidence that IPOs with more shares to lock up, as well as those selecting longer lockup periods, have more accurate management earnings forecasts. These results are robust to a number of sensitivity tests.In the third essay, we examine the impact of geographic location on the short–run underpricing of French initial public offerings (IPOs). The results show that firms located in close proximity to the financial centre, Paris, are less underpriced than distant ones. These findings provide empirical support to the argument that uncertainty about IPO value increases with distance from Paris. In other words, geographic proximity improves the quality of collected information on IPO firms, which lowers their costs of going public and decreases the level of initial returns.

Bakgrund och problem: Det långsiktiga värdeskapandet av Private Equity (PE)- och Venture Capital (VC)-bolag är ett fenomen som forskats kring sedan dess uppenbarelse i mitten av 80-talet. Tidigare forskning har främst fokuserat på portföljbolagens prestation under ägande, medan forskningen är gles gällande de långsiktiga konsekvenserna av PE- och VC-ägande. Trots tidigare forskning inom området, som sträcker sig över tre decennier, finns det ingen etablerad konsensus om de långsiktiga effekterna av PE- och VC-finansiering. Med tanke på den tvetydiga forskningen och det faktum att det inte råder någon konsensus inom området syftar denna studie att undersöka fenomenet på den svenska marknaden. Syfte: Denna studie syftar till att analysera huruvida det råder en operationell prestationsskillnad mellan tidigare PE- och VC-ägda portföljbolag gentemot dess branschkonkurrenter efter avyttring genom börsnotering. Vidare ämnar studien  analysera de bakomliggande faktorerna till den tänkbara prestationsskillnaden samt utreda om dessa varierar beroende på vilken aktör som tidigare stått för ägandet. Metod: Undersökningen genomfördes på den svenska marknaden mellan 2000 och 2017 med EBITDA-marginalen, omsättning per anställd, avkastning på sysselsatt kapital, operativa kassaflöden/totala tillgångar och rörelsekapital/omsättning som indikator på operationell prestation. I linje med tidigare forskning tillämpar följande studie en kvantitativ forskningsmetod, en deduktiv design och använder både ett parametrisk och icke parametrisk test i syfte att avgöra den statistiska säkerheten i resultaten. Slutsats: Studien konstaterar att den långsiktiga operationella prestationen för tidigare PE-ägda portföljbolag är sämre än den för branschkonkurrenter. Resultaten fastställer dock en kortsiktig överprestation som grundar sig i varaktiga effekter av effektiviseringsåtgärder från ägandeperioden. I motsats till detta, indikerar VC-ägda portföljbolag på en operativ underprestation, relativt branschkonkurrenter, på kort- och lång sikt men på grund av ett begränsat urval av portföljbolag kan detta inte statistiskt säkerställas. / Background and problem: The long term value creation of Private Equity (PE) and Venture (VC) Capital firms is a phenomena that has been debated and researched since its revelation in the mid 80’s. Previous research has primarily focused on the performance of portfolio companies during ownership, while the offer is relatively sparse investigating the long term consequences of PE and VC ownership after divestment. Despite previous research within the field, extending over three decades, there is no established consensus of the long term results of PE and VC financing. Given the contradiction of previous research the study aims to investigate the phenomena in detail on the Swedish market. Purpose: The study aims is to investigate how formerly Private Equity (PE) and Venture Capital (VC) backed portfolio companies preform, relative industry peers, after divestment through IPO. The study is based upon five key operational metrics and further strives to analyse and determine the explanatory variables to the presumed performance deviations and if these vary depending on which actor who previously was responsible for the ownership. Methodology: The study was conducted on the Swedish market between 2000 and 2017 using the EBITDA-margin, RPE, ROCE, operational cash flows to total assets and net working capital to sales as operational determinants for long- and short term performance. In line with previous research the following event study applies a quantitative research method, a deductive design and uses both a parametric and a non-parametric test to determine the statistical significance of the results. Conclusion: The study concludes that the long term operational performance of previously PE- owned portfolio companies is inferior to that of industry peers. However, the results conclude that the portfolio companies over perform industry peers in the short term due to lasting effects of efficiency processes from the ownership period. In contrary to previous results VC-owned portfolio companies indicate an operational under performance in the short and long term but due to a limited selection of portfolio companies this cannot be statistically proven.