Pre-Stressed FRP-Concrete Composite Structural Members

Fiber reinforced plastic FRP formed about concrete piles and columns. The FRP components generally includes an exterior shell and an interior protruding portions. The concrete filled FRP tubes are enhanced by prestressing the concrete core, thereby increasing the bond with the tube and placing the tube in an active hoop tension. The prestressing can be developed by either post-tensioning a series of strands(or tendons) that are placed inside the core, or by using expansive core materials which do expand upon curing and will therefore impose an active pressure on the confining tube. The bond can be developed by either internal resin grids, FRP spirals, FRP orthotropic grids, sand-resin coating, bonding agent or protruded ribs. The system can be used as a fender pile, bearing pile, bridge pier column, or any structural column. The system can be made by pultrusion, SCRIMP, REM, centrifugal methods or hand lay-up. The invention can additionally enhance the compressive, flexural and shear

Performance of FRP-Retrofitted Concrete Bridge Columns Under Blast Loading

Contrary to military or essential government buildings, most bridges are designed without any consideration for blast resistance. Fiber-reinforced polymers (FRPs) can provide an effective means for strengthening of critical bridges against such loading. This study has focused on the effectiveness of FRP retrofitting in the dynamic response of reinforced concrete bridge columns under blast loading. Using a simplified equivalent I-section with a virtual material lumped at the two flanges; a lightly meshed uniaxial finite element model was developed and successfully validated against previous studies. The proposed model was then used for a thorough parametric study on the blast resistance of bridge substructures in the form of a single-column, two-column pier frame, and an entire bridge. The study showed the benefits of strengthening with composites against blast loading. The FRP tensile strength and diameter-to-thickness ratio, steel reinforcement ratio, and column length and damping ratio significantly affect the blast resistance of an FRP-retrofitted bridge. Finally, based on the parametric study results, predictive equations with multiple linear regression and high order terms were developed statistically for the FRP retrofit design of single columns against blast loading

User-centric Music Information Retrieval

The rapid growth of the Internet and the advancements of the Web technologies have made it possible for users to have access to large amounts of on-line music data, including music acoustic signals, lyrics, style/mood labels, and user-assigned tags. The progress has made music listening more fun, but has raised an issue of how to organize this data, and more generally, how computer programs can assist users in their music experience. An important subject in computer-aided music listening is music retrieval, i.e., the issue of efficiently helping users in locating the music they are looking for. Traditionally, songs were organized in a hierarchical structure such as genre-\u3eartist-\u3ealbum-\u3etrack, to facilitate the users’ navigation. However, the intentions of the users are often hard to be captured in such a simply organized structure. The users may want to listen to music of a particular mood, style or topic; and/or any songs similar to some given music samples. This motivated us to work on user-centric music retrieval system to improve users’ satisfaction with the system. The traditional music information retrieval research was mainly concerned with classification, clustering, identification, and similarity search of acoustic data of music by way of feature extraction algorithms and machine learning techniques. More recently the music information retrieval research has focused on utilizing other types of data, such as lyrics, user access patterns, and user-defined tags, and on targeting non-genre categories for classification, such as mood labels and styles. This dissertation focused on investigating and developing effective data mining techniques for (1) organizing and annotating music data with styles, moods and user-assigned tags; (2) performing effective analysis of music data with features from diverse information sources; and (3) recommending music songs to the users utilizing both content features and user access patterns

Prevention of non-communicable disease in a population in nutrition transition: Tehran Lipid and Glucose Study phase II

<p>Abstract</p> <p>Background</p> <p>The Tehran Lipid and Glucose Study (TLGS) is a long term integrated community-based program for prevention of non-communicable disorders (NCD) by development of a healthy lifestyle and reduction of NCD risk factors. The study begun in 1999, is ongoing, to be continued for at least 20 years. A primary survey was done to collect baseline data in 15005 individuals, over 3 years of age, selected from cohorts of three medical heath centers. A questionnaire for past medical history and data was completed during interviews; blood pressure, pulse rate, and anthropometrical measurements and a limited physical examination were performed and lipid profiles, fasting blood sugar and 2-hours-postload-glucose challenge were measured. A DNA bank was also collected. For those subjects aged over 30 years, Rose questionnaire was completed and an electrocardiogram was taken. Data collected were directly stored in computers as database software- computer assisted system. The aim of this study is to evaluate the feasibility and effectiveness of lifestyle modification in preventing or postponing the development of NCD risk factors and outcomes in the TLGS population.</p> <p>Design and methods</p> <p>In phase II of the TLGS, lifestyle interventions were implemented in 5630 people and 9375 individuals served as controls. Primary, secondary and tertiary interventions were designed based on specific target groups including schoolchildren, housewives, and high-risk persons. Officials of various sectors such as health, education, municipality, police, media, traders and community leaders were actively engaged as decision makers and collaborators. Interventional strategies were based on lifestyle modifications in diet, smoking and physical activity through face-to-face education, leaflets & brochures, school program alterations, training volunteers as health team and treating patients with NCD risk factors. Collection of demographic, clinical and laboratory data will be repeated every 3 years to assess the effects of different interventions in the intervention group as compared to control group.</p> <p>Conclusion</p> <p>This controlled community intervention will test the possibility of preventing or delaying the onset of non-communicable risk factors and disorders in a population in nutrition transition.</p> <p>Trial registration</p> <p>ISRCTN52588395</p

NDT and instrumentation in an undergraduate concrete lab

The first year implementation of an NSF-ILI project for enhancing the concrete lab with NDT and instrumentation modules is discussed. A two-semester laboratory is developed to parallel the lectures in the two concrete courses; namely, Reinforced Concrete Structures and Concrete Design project. The new laboratory has significantly increased students\u27 interest in, and learning from, the courses

Dynamic Buckling And Post-Buckling Of Stressed Composite Arches

A stressed composite arch differs from its rigid counterpart by two distinctive characteristics; first, each section of the arch contains a non-uniform distribution of prestressing forces, and second, geometry of the arch is a function of the prestressing forces. Dynamic snap-through buckling of stressed composite arches is investigated using a convected corotational formulation of a two-node three-layer sandwich beam element. The model includes both geometric and material nonlinearities. Dynamic response is analyzed in the time domain using a Wilson-θ implicit integration scheme. Results indicate good stability behavior for stressed composite arches as compared to their homogeneous counterparts

A New Concrete-Filled Hollow Frp Composite Column

An effective use of fiber reinforced plastic (FRP) shapes in infrastructure is in the form of composite construction with reinforced concrete. A novel composite column is proposed that is similar to the classic concrete-filled steel tubes, except that steel has been replaced with a hollow FRP shell. The FRP shell, while an integral part of the structure, is also the pour form for concrete. The shell may be a filament-wound or a multi-layer FRP pipe with a layer of longitudinal fibers sandwiched between two piles of circumferential fibers. The proposed column offers high strength and ductility in addition to excellent durability. Behavior of the proposed column is studied by developing two analytical tools; a new passive confinement model for externally reinforced concrete columns, and a composite action model that evaluates the lateral stiffening effect of the jacket. Results are compared with recent studies of fiber-wrapped columns

Novel Frp-Concrete Composite Construction For The Infrastructure

A novel composite column is proposed that is similar to the classic concrete-filled steel tubes, except that steel has been replaced with Fiber Reinforced Plastic (FRP) shapes. The FRP tube, while an integral part of the structure, is also the pour form for concrete. The tube may be a filament-wound pipe or a multi-layer FRP shape with a layer of longitudinal fibers sandwiched between two layers of circumferential fibers. The principle behind the proposed system is the same as in fiber-wrapping practice where concrete core is both protected and confined by a fiber jacket. A new passive confinement model is proposed for external confinement of concrete columns with fiber-wraps or FRP tubes. The model accounts for the varying lateral expansion of concrete (Poisson\u27s effect), and the non-ductile behavior of fiber composites. Results are compared with recent studies of fiber-wrapped columns

Behavior of concrete columns confined by fiber composites

External confinement of concrete by means of high-strength fiber composites can significantly enhance its strength and ductility as well as result in large energy absorption capacity. The confinement mechanism may include fiber-wrapping of existing columns as a retrofitting measure or encasement of concrete in a fiber reinforced plastic (FRP) tube for new construction. Proper design of such hybrid columns, however, requires an accurate estimate of the performance enhancement. Current design methods use simple extension of the models developed for conventional reinforced concrete columns. Results from a series of uniaxial compression tests on concrete-filled FRP tubes are compared with the available confinement models in the literature. The present study indicates that these models generally result in overestimating the strength and unsafe design. The study also shows a unique characteristic of confinement with fiber composites in that, unlike steel, FRP curtails the dilation tendency of concrete, as it reverses the direction of volumetric strains. This paper provides a framework for better understanding of the behavior of fiber-wrapped or FRP-encased concrete columns