Pushover analysis of an existing reinforced concrete bridge:Jamboree Road Overcrossing in Irvine, California

The work for the present thesis started in California, during my semester as an exchange student overseas. California is known worldwide for its seismicity and its effort in the earthquake engineering research field. For this reason, I immediately found interesting the Structural Dynamics Professor, Maria Q. Feng's proposal, to work on a pushover analysis of the existing Jamboree Road Overcrossing bridge. Concrete is a popular building material in California, and for the most part, it serves its functions well. However, concrete is inherently brittle and performs poorly during earthquakes if not reinforced properly. The San Fernando Earthquake of 1971 dramatically demonstrated this characteristic. Shortly thereafter, code writers revised the design provisions for new concrete buildings so to provide adequate ductility to resist strong ground shaking. There remain, nonetheless, millions of square feet of non-ductile concrete buildings in California. The purpose of this work is to perform a Pushover Analysis and compare the results with those of a Nonlinear Time-History Analysis of an existing bridge, located in Southern California. The analyses have been executed through the software OpenSees, the Open System for Earthquake Engineering Simulation. The bridge Jamboree Road Overcrossing is classified as a Standard Ordinary Bridge. In fact, the JRO is a typical three-span continuous cast-in-place prestressed post-tension box-girder. The total length of the bridge is 366 ft., and the height of the two bents are respectively 26,41 ft. and 28,41 ft.. Both the Pushover Analysis and the Nonlinear Time-History Analysis require the use of a model that takes into account for the nonlinearities of the system. In fact, in order to execute nonlinear analyses of highway bridges it is essential to incorporate an accurate model of the material behavior. It has been observed that, after the occurrence of destructive earthquakes, one of the most damaged elements on highway bridges is a column. To evaluate the performance of bridge columns during seismic events an adequate model of the column must be incorporated. Part of the work of the present thesis is, in fact, dedicated to the modeling of bents. Different types of nonlinear element have been studied and modeled, with emphasis on the plasticity zone length determination and location. Furthermore, different models for concrete and steel materials have been considered, and the selection of the parameters that define the constitutive laws of the different materials have been accurate. The work is structured into four chapters, to follow a brief overview of the content. The first chapter introduces the concepts related to capacity design, as the actual philosophy of seismic design. Furthermore, nonlinear analyses both static, pushover, and dynamic, time-history, are presented. The final paragraph concludes with a short description on how to determine the seismic demand at a specific site, according to the latest design criteria in California. The second chapter deals with the formulation of force-based finite elements and the issues regarding the objectivity of the response in nonlinear field. Both concentrated and distributed plasticity elements are discussed into detail. The third chapter presents the existing structure, the software used OpenSees, and the modeling assumptions and issues. The creation of the nonlinear model represents a central part in this work. Nonlinear material constitutive laws, for concrete and reinforcing steel, are discussed into detail; as well as the different scenarios employed in the columns modeling. Finally, the results of the pushover analysis are presented in chapter four. Capacity curves are examined for the different model scenarios used, and failure modes of concrete and steel are discussed. Capacity curve is converted into capacity spectrum and intersected with the design spectrum. In the last paragraph, the results of nonlinear time-history analyses are compared to those of pushover analysis.

Corpora e universali della traduzione in ambito sociologico: il caso degli anglicismi nella rivista “Lavoro Sociale”

Contacts between languages have always led to mutual influence. Today, the position of authority of the English language affects Italian in many ways, especially in the scientific and technical fields. When new studies conceived in the English-speaking world reach the Italian public, we are faced not only with the translation of texts, but most importantly the rendition of theoretical constructs that do not always have a suitable rendering in the target language. That is why we often find anglicisms in Italian texts. This work aims to show their frequency in a specific field, underlying how and when they are used, and sometimes preferred to the Italian corresponding word. This dissertation looks at a sample of essays from the specialised magazine “Lavoro Sociale”, published by Edizioni Centro Studi Erickson, searching for borrowings from English and discussing their use in order to make hypotheses on the reasons of this phenomenon, against the wider background of translation studies and translation universals research. What I am more interested in is the understanding of the similarities and differences in the use of anglicisms by authors of Italian texts and translators from English into Italian, so that I can figure out what the main dynamics and tendencies are. The whole paper is has four parts. Chapter 1 briefly explains the theoretical background on translation studies, and introduces and discusses the notion of translation universals. After that, the research methodology and theoretical background on linguistic borrowings (especially anglicisms) in Italian are summarized. Chapter 2 presents the study, explaining the organisation of the material, the methodology used and the object of interest. Chapter 3 is the core of the dissertation because it contains the qualitative and quantitative data taken from the texts and the examination of the dynamics of the use of anglicisms. Finally, Chapter 4 compares the conclusions drawn from the previous chapter with the opinions of authors, translators and proof-readers, whom I asked to answer a questionnaire written specifically to investigate the mechanisms and choices behind their use of anglicisms.

Studio retrospettico sul ruolo della strumentazione nei fallimenti meccanici a seguito di Trattamento Chirurgico nelle Scoliosi dell'adulto

The spinal column performs important functions in the body, including the support of the entire weight of the human body, the ability to orientate the head in space, bending, flexing and rotating the body. Diseases affecting the spine are manifold: the most frequent is scoliosis, which often affects the female population. It is often treated surgically with a very high percentage of failures. The aim of the thesis is to study the role of instrumentation in mechanical failures encountered 12 months after surgery in the treatment of scoliosis. For the purposes of the study, we analyzed specific biomechanical parameters. The pelvic angles determine the position of the pelvis, while the imbalance parameters the structure of the body. We infer other parameters by analyzing the characteristics of the implanted instrumentation. Initially, the anatomy is described of the spine and vertebrae, the equipment used and the possible failures that may occur after surgery. Subsequently, the materials and methods used for the analysis of the above-mentioned parameters for the 61 patients are reported. All data are obtained by the observation of pre and post-operative x-rays with a special program, by reading reports from operators and by medical records. In the fourth chapter, we report the results: the overall failure rate is 60.9%; the types of failures that occurred are rupture of bars and rupture of bars simultaneously to PJK. The most influential parameters on results of the progress of the surgery are the type of material used and the BMI. It is estimated a high percentage of failures in patients treated with implants of cobalt chromium alloys (90.0%). According to the results obtained, it is possible to understand the aspects that in the future should be studied, in order to find a solution to the most frequent surgical failures.