Efeito do carregamento cíclico e da pré-fendilhação do betão no comportamento de lajes de betão armado reforçadas à flexão com laminados de CFRP inseridos

Dissertação de mestrado integrado em Engenharia Civil

Reforço à flexão de lajes de betão armado com laminados de CFRP pré-esforçados

Dissertação de mestrado integrado em Engenharia Civil (área de especialização em Estruturas e Geotecnia)

The real economic effects of cross-delistingfrom the united states: evidence on post-operating performance, financial constraints and stock crash risk

Tese de Doutoramento em Ciências Empresariais.

Failure mechanism under tensile loads in CFRP 0-90º cross-ply laminates containing voids

The failure mechanism of a voided CFRP 0-90° cross-ply laminate under tensile loads applied in one direction was studied in this Final Degree Project. For this purpose, voided coupons were manufactured for being tested and a FEA was done. In both investigations, voids were placed in 90º and 0º direction, in order to understand the void location influence. On the one hand, the behaviour of the voided laminates was investigated through a FEM in order to preview the stress distribution within the material. On the other hand, voided specimens where manufactured by applying blowing agent in between the inner layers. These specimens were tested by a quasi-static step wise tensile test where data showing its real behaviour was collected. Specimens were X-rayed after each step of the test in order to investigate the failure mechanism of the composite. Data from the test was studied so that relations such as strength of the laminates, crack density per stress, void length per first crack at the void and void area per first crack at the specimen could be characterized

Systematic Identification of High Crash Locations Final Report, 2001

Federal and state policy makers increasingly emphasize the need to reduce highway crash rates. This emphasis is demonstrated in Iowa’s recently released draft Iowa Strategic Highway Safety Plan and by the U.S. Department of Transportation’s placement of “improved transportation safety” at the top of its list of strategic goals. Thus, finding improved methods to enhance highway safety has become a top priority at highway agencies. The objective of this project is to develop tools and procedures by which Iowa engineers can identify potentially hazardous roadway locations and designs, and to demonstrate the utility of these tools by developing candidate lists of high crash locations in the State. An initial task, building an integrated database to facilitate the tools and procedures, is an important product, in and of itself. Accordingly, the Iowa Department of Transportation (Iowa DOT) Geographic Information Management System (GIMS) and Geographic Information System Accident Analysis and Location System (GIS-ALAS) databases were integrated with available digital imagery. (The GIMS database contains roadway characteristics, e.g., lane width, surface and shoulder type, and traffic volume, for all public roadways. GIS-ALAS records include data, e.g., vehicles, drivers, roadway conditions, and the crash severity, for crashes occurring on public roadways during then past 10 years.)

Effective Structural Concrete Repair, Volume 1 of 3, Repair of Impact Damaged Prestressed Concrete Beams with CFRP, March 2004

Structural concrete is one of the most commonly used construction materials in the United States. However, due to changes in design specifications, aging, vehicle impact, etc. – there is a need for new procedures for repairing concrete (reinforced or pretressed) superstructures and substructures. Thus, the overall objective of this investigation was to develop innovative cost effective repair methods for various concrete elements. In consultation with the project advisory committee, it was decided to evaluate the following three repair methods: • Carbon fiber reinforced polymers (CFRPs) for use in repairing damaged prestressed concrete bridges • Fiber reinforced polymers (FRPs) for preventing chloride penetration of bridge columns • Various patch materials The initial results of these evaluations are presented in this three volume final report. Each evaluation is briefly described in the following paragraphs. A more detailed abstract of each evaluation accompanies the volume on that particular investigation.

Percorsi dell'emigrazione italiana in Svizzera tra fonti orali e scritture di gente comune (1946-1974)

Sintesi II presente lavoro di ricerca, maturato nel quadro di un dottorato in storia contemporanea, propone una ricostruzione dei percorsi materiali e dei percorsi culturali degli emigrati italiani in Svizzera tra la tìne della Seconda guerra mondiale e i primi anni Settanta. Le principali fonti di prima mano adoperate nella ricerca consistono in tre diversi generi di narrazioni autobiogratìche: le fonti orali (cento interviste complessive raccolte e analizzate); le scritture epistolari (tre fondi per un totale di circa duecento lettere); le scritture scolastiche di adolescenti e giovani emigrati italiani, iscritti, tra la fine degli anni Sessanta e i primi anni Settanta, ad una scuola privata del Canton Zurigo (circa seicento temi validi come prova di lingua italiana per il conseguimento della licenza media tra il 1973 e il 1974). Le fonti soggettive raccolte hanno permesso di tracciare i profili di numerosi di percorsi migratori vissuti da queste persone, lavorando, in primo luogo, sulla loro dimensione materiale, ovvero sulle tappe íìsiche, dal viaggio, alla ricerca del posto di lavoro e dell'alloggio, alla formazione di una famiglia, agli strumenti utilizzati per mantenersi in contatto con il proprio paese d'origine. Si sono poi inquadrate alcune delle possibili evoluzioni ideologiche e culturali, nei termini consentiti dallo studio della memoria e delle rappresentazioni di sé, offerte dagli emigrati stessi. In sintesi, quindi, il lavoro propone una ricostruzione di un frammento di storia dell'emigrazione italiana, con tutte le specitìcità legate a un paese di accoglienza, la Svizzera, e a un periodo storico, il Secondo dopoguerra. Alcuni dei caratteri principali dei percorsi materiali sono senz'altro legati alle peculiarità della legislazione svizzera, con la detìnizione di "straniero" che dava, le condizioni di vita che rendeva praticabili e possibili, i passaggi di tempo che imponeva per avere una permesso a tempo indeterminato, per raggiungere una certa stabilità, per ricomporre il proprio nucleo familiare. Anche alcuni fenomeni culturali erano legati a queste dimensioni specitïche, per cui non hanno riscontro, negli stessi termini, in altri contesti e in altri periodi. Accanto alle peculiarità e alle differenze che questa storia ha rispetto ad altre storie di emigrazione legate ad altri paesi e ad altri contesti, dal lavoro emergono processi e fenomeni di interesse più generale, qualora ci si interessi di fenomeni migratori, di conflitti, di inclusione e di esclusione di gruppi umani differenti. Alcune delle problematiche che si sono poste nella storia in analisi -per esempio quelle relative alla scolarizzazione dei minori, al rapporto tra diritto di residenza e obbligo di impiego, alla presenza di clandestini e al loro rapporto con associazioni o gruppi di assistenza legali o illegali -sono senza dubbio utili riferimenti per chi oggi voglia ragionare su problematiche analoghe poste in diversi contesti.

The Effect of Four-Lane to Three-Lane Conversion on the Number of Crashes and Crash Rates in Iowa Roads, June 2005

We analyze crash data collected by the Iowa Department of Transportation using Bayesian methods. The data set includes monthly crash numbers, estimated monthly traffic volumes, site length and other information collected at 30 paired sites in Iowa over more than 20 years during which an intervention experiment was set up. The intervention consisted in transforming 15 undivided road segments from four-lane to three lanes, while an additional 15 segments, thought to be comparable in terms of traffic safety-related characteristics were not converted. The main objective of this work is to find out whether the intervention reduces the number of crashes and the crash rates at the treated sites. We fitted a hierarchical Poisson regression model with a change-point to the number of monthly crashes per mile at each of the sites. Explanatory variables in the model included estimated monthly traffic volume, time, an indicator for intervention reflecting whether the site was a “treatment” or a “control” site, and various interactions. We accounted for seasonal effects in the number of crashes at a site by including smooth trigonometric functions with three different periods to reflect the four seasons of the year. A change-point at the month and year in which the intervention was completed for treated sites was also included. The number of crashes at a site can be thought to follow a Poisson distribution. To estimate the association between crashes and the explanatory variables, we used a log link function and added a random effect to account for overdispersion and for autocorrelation among observations obtained at the same site. We used proper but non-informative priors for all parameters in the model, and carried out all calculations using Markov chain Monte Carlo methods implemented in WinBUGS. We evaluated the effect of the four to three-lane conversion by comparing the expected number of crashes per year per mile during the years preceding the conversion and following the conversion for treatment and control sites. We estimated this difference using the observed traffic volumes at each site and also on a per 100,000,000 vehicles. We also conducted a prospective analysis to forecast the expected number of crashes per mile at each site in the study one year, three years and five years following the four to three-lane conversion. Posterior predictive distributions of the number of crashes, the crash rate and the percent reduction in crashes per mile were obtained for each site for the months of January and June one, three and five years after completion of the intervention. The model appears to fit the data well. We found that in most sites, the intervention was effective and reduced the number of crashes. Overall, and for the observed traffic volumes, the reduction in the expected number of crashes per year and mile at converted sites was 32.3% (31.4% to 33.5% with 95% probability) while at the control sites, the reduction was estimated to be 7.1% (5.7% to 8.2% with 95% probability). When the reduction in the expected number of crashes per year, mile and 100,000,000 AADT was computed, the estimates were 44.3% (43.9% to 44.6%) and 25.5% (24.6% to 26.0%) for converted and control sites, respectively. In both cases, the difference in the percent reduction in the expected number of crashes during the years following the conversion was significantly larger at converted sites than at control sites, even though the number of crashes appears to decline over time at all sites. Results indicate that the reduction in the expected number of sites per mile has a steeper negative slope at converted than at control sites. Consistent with this, the forecasted reduction in the number of crashes per year and mile during the years after completion of the conversion at converted sites is more pronounced than at control sites. Seasonal effects on the number of crashes have been well-documented. In this dataset, we found that, as expected, the expected number of monthly crashes per mile tends to be higher during winter months than during the rest of the year. Perhaps more interestingly, we found that there is an interaction between the four to three-lane conversion and season; the reduction in the number of crashes appears to be more pronounced during months, when the weather is nice than during other times of the year, even though a reduction was estimated for the entire year. Thus, it appears that the four to three-lane conversion, while effective year-round, is particularly effective in reducing the expected number of crashes in nice weather.

Crash Data Validation: An Iowa Case Study, February, 2007

With the quickening pace of crash reporting, the statistical editing of data on a weekly basis, and the ability to provide working databases to users at CTRE/Iowa Traffic Safety Data Service, the University of Iowa, and the Iowa DOT, databases that would be considered incomplete by past standards of static data files are in “public use” even as the dynamic nature of the central DOT database allows changes to be made to both the aggregate of data and to the individual crashes already reported. Moreover, “definitive” analyses of serious crashes will, by their nature, lag seriously behind the preliminary data files. Even after these analyses, the dynamic nature of the mainframe data file means that crash numbers can continue to change long after the incident year. The Iowa DOT, its Office of Driver Services (the “data owner”), and institutional data users/distributors must establish data use, distribution, and labeling protocols to deal with the new, dynamic nature of data. In order to set these protocols, data must be collected concerning the magnitude of difference between database records and crash narratives and diagrams. This study determines the difference between database records and crash narratives for the Iowa Department of Transportation’s Office of Traffic and Safety crash database and the impacts of this difference.

Motor Vehicle Crash Fatalities for Week Ending, March 21, 2008

Motor Vehicle Crash Fatalities

Motor Vehicle Crash Fatalities for Week Ending, March 28, 2008

Motor Vehicle Crash Fatalities

Motor Vehicle Crash Fatalities for Week Ending: April 4, 2008

Vehicle fatalities from around the state of Iowa.

Motor Vehicle Crash Fatalities for Week Ending, April 4, 2008

Motor Vehicle Crash Fatalities

Motor Vehicle Crash Fatalities for Week Ending, April 11, 2008

Motor Vehicle Crash Fatalities

Motor Vehicle Crash Fatalities for Week Ending, April 18, 2008

Motor Vehicle Crash Fatalities