STRUCTURAL APPLICATIONS OF COMPOSITES IN INFRASTRUCTURE
also being used in combination with concrete slabs to develop and test new model bridges by M. Saiidi and F. Gordaninejad at University of Nevada, Reno. Since the 1930's, glass fiber reinforced plastic (GFRP) has been considered a good substitute for steel as a reinforcement ofconcrete or to create an initial state ofcompressive stress in concrete by prestressing GFRP tendons~ Reinfofcement and prestressing of concrete are common ways to miti.gate the lo\v tensile strength of concrete in order to take advantage of its high compressive strength~ In fact, reinforced concrete is a fiber reinforced composite material in '''hieh the advantageous properties of the constituents are high tensile strength of the rebars (steel or FRP) and the high compressive strength of the concrete matrix.. Surface protection of certain types of continuous glass fibers, particularly E..glass fibers, from attacks by the environment or alkaline reaction with concrete has been accomplished by coatings, including resins. For example, a typical continuous E..glass fiber reinforced plastic rebar has a 55% glass vol.ume fraction enlbedded in a matrix ofv'inylester or isophthalic resin~ These thermoset resin systems have ex~ ceHent resistance to corrosion a.nd impact, are good electrical and thermal insulators, are easy to manufacture, and are cost effective~ Thermoplastic rebars, which are more expensive than thermosets, have a potential for reshaping and \velding in the field which motivates current investigation oftheir potential applications in constnlction# Aramid fibers (e.g#, DuPont's Kevlar® 29, 49, 149) with higher tensile strength (3~62 GPa) and stiffness (124 G·:Pa for Kevlar@ 49) than glass fibers are being used to devel.op high strength rebars and cables by DoS. and Japanese manufac~ turerso AraIuid fibers have good chemical resistance to sol .. vents, dilute ac...i.ds~ and bases, as well a..1O) excellent fatigue strength and low relaxationo Carbon fiber reinforced plastic rebars and seven wire strands (cables) \vith higher stiffness than glass or aramid fiber rehars are also manufactured as reinforcing or prestressing eleluents for structural appHca~ tions, Ho\vever, carbon fiber rebars and cables are even more expensive than aramid or glass rebars, Chopped fiber rein-· forced plastic rods are being manufactured by extrusion~ 'fhesr.
Mechanical Behavior of Polypropylene-based Honeycomb-Core Composite Sandwich Structures
This article presents results from an experimental study, investigating the effects of core thickness on the mechanical properties of composite sandwich structures with polypropylene(PP)-based honeycomb core and glass fiber-reinforced polymer (GFRP) face-sheets fabricated by hand lay-up technique. Epoxy matrix and non-crimp glass fibers were used for the production of GFRP laminates. Flatwise compression (FC), edgewise compression (EC), three-point bending (3PB) and double cantilever beam (DCB) tests were performed to evaluate the mechanical behavior of the composite sandwich structures (CSSs). Based on the FC tests, an increase in the compressive modulus and strength was observed with an increase in the core thickness. For EC tests, peak loads up to crush of the sandwich panel is discussed using core thickness. According to the 3PB tests, a decrease in core shear stress and facesheet bending stress was observed as the core thickness increases.
Study of External Parasites Infesting Carcharhinus Melanopterus Fish From The Red Sea In Jeddah, Saudi Arabia
Parasitic diseases are harmful and limiting factors in breeding and rearing ornamental fish industry, such as the Monogenea ( Dactylogyrus sp and Erpocotyletiburonis ) and copepod ( Pandarus sinuatus  and Anchistrotostangi ). The copepod and the monogenean are gill parasites found on the shark; CarcharhinusMelanopterus . The primary purpose of this study was to determine the parasitic infections of sharks in red sea in Jeddah. For this purpose, 19 female C. Melanopterus and 14 male C. Melanopterus were first examined for ectoparasites using wet mount under a light microscope. All male sharks had Monogenea and/or copepod in their gill and only 3 females haven’t infections. Then, we aimed to find a combination of copepod and monogenea infection in C. Melanopterus gills. 50% of male and 42% of female were infected by copepod and monogenea. Our findings revealed that the protozoan infections are very common among sharks. Although, no gross pathology was observed among infected shark, but it is likely that in case of any changes in the environment, then parasitic infections could be harmful.