Behavior and strength of beams cast with ultra high strength concrete containing different types of fibers

Ultra-high performance concrete (UHPC) is a special type of concrete with extraordinary potentials in terms of strength and durability performance. Its production and application implement the most up-to-date knowledge and technology of concrete manufacturing. Sophisticated structural designs in bridges and high-rise buildings, repair works and special structures like nuclear facilities are currently the main fields of applications of UHPC. This paper aimed to evaluate the behavior of ultra-high strength concrete beams. This paper also aimed to determine the effect of adding fibers and explore their effect upon the behavior and strength of the reinforced concrete beams. A total of twelve simple concrete beams with and without shear reinforcements were tested in flexure. The main variables taken into consideration in this research were the type of fibers and the percentage of longitudinal reinforcement as well as the existence or absence of the web reinforcement. Two types of fibers were used including steel and polypropylene fibers. The behavior of the tested beams was investigated with special attention to the deflection under different stages of loading, initial cracking, cracking pattern, and ultimate load. Increased number of cracks was observed at the end of loading due to the use of fibers, which led to the reduced width of cracks. This led to increased stiffness and higher values of maximum loads

Morphology and properties of polymer matrix nanocomposites

Carbon nanotubes (CNTs) have become strongly promising nano-particles for developing novel smart polymer matrix nanocomposites to satisfy the ever increasing design requirements of the recent avenues of space industry and other special structural applications. The objective of this paper is to investigate the influence of doped and dispersed CNTs in polymer matrix on its intrinsic properties. Three different types of polymers; polyvinylchloride (PVC), polymethylemethacrylate (PMMA), and polystyrene (PS) were subjected to this experimental investigation. CNTs/polymer matrix composites with a content ratio of CNTs up to 5% by weight were synthesized in lab. The nanocomposites were then characterized by measuring their mechanical, electrical, and thermal properties. In addition, thermo gravimetric analysis (TGA), Fourier transform infra red spectroscopy (FTIR), and scanning electron microscopy (SEM) were applied, and the results are presented and discussed. It can be generally concluded that both PMMA and PS polymers disclosed much better matching ability and cross linking ability with the interweaving CNTs than the PVC. Both PMMA and PS polymers may thus be nominated for further extension of the investigation to cover a wider range of CNTs content ratios in an endeavour towards searching for maximum specific performance properties of such nanocomposites

Eclipse ESCET™: The Eclipse Supervisory Control Engineering Toolkit

The Eclipse Supervisory Control Engineering Toolkit (ESCET™) is an open-source project to provide a model-based approach and toolkit for developing supervisory controllers, targeting their entire engineering process. It supports synthesis-based engineering of supervisory controllers for discrete-event systems, combining model-based engineering with computer-aided design to automatically generate correct-by-construction controllers. At its heart is supervisory controller synthesis, a formal technique for the automatic derivation of supervisory controllers from the unrestricted system behavior and system requirements. Vital for the future development of these techniques and tools is the ESCET project’s open environment, allowing industry and academia to collaborate on creating an industrial-strength toolkit. We report on some crucial developments of the toolkit in the context of research projects with Rijkswaterstaat and ASML that have considerably improved its capability to deal with the complexity of real-life systems as well as its usability