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.
Structural evaluation of a novel box beam system of Pultruded Fibre Reinforced Polymer shapes
Presented in this thesis is an evaluation of a novel box beam system of Pul- 
truded Fibre Reinforced Polymer (PFRP) shapes. The flat-pack modular beam 
system consists of separate PFRP flange and web shapes joined together with 
a new method of mechanical fastening. It is based on the first generation Star- 
tlink building system, conceived by UK engineers in 1999. The Startlink building 
system is introduced, and classified within the scope of Modern Methods of Con- 
struction (MMC), and its merits are discussed. In the context of MMC a critical 
review by the author finds that, although the proposed 1999 generation Startlink 
system offers design flexibility, it will probably have a limited market potential. 
The novel use of the steel MlO Unistrut connection method as a means of 
fastening distinct PFRP shapes in a building system is characterised. Individ- 
ual connector design parameters for joint stiffness and resistance are identified 
and determined, under pure shear loading. The results of a series of physical 
tests show no significant loss of stiffness or strength with long term environmen- 
tal exposure. Values of key mechanical properties for design calculations are 
recommended. 
A 400 x 200 x 2848 mm prototype PFRP box beam assembly is fabricated from 
two flange and two web panel-type shapes, cut from existing off-the-shelf PFRP 
shapes. This is 60 mm deeper than the largest single PFRP shape that could 
be used as a beam. The assembly is joined at the web-flange junction with M10 
Unistrut connectors set at various spacing's, in the range 50 to 400 mm. These 
connectors carry the longitudinal shear that is generated between the joined 
shapes when the modular assembly is in flexure, Theoretical deflections, cal- 
culated using a modified form of a partial-interaction analysis model developed 
for composite concrete and steel structures, are predicted for the assembly ac- 
counting for the finite shear stiffness of the web-flange connection. A series of 
16 four-point bending load tests on the beam assembly, across two load arrange- 
ments, show that its performance is linked to the designated spacing of the M10 
Unistrut connections. The flexural rigidity and degree of interaction present in 
the assembly are determined from analysis of vertical deflections and longitudi- 
nal strains, as the beam is deformed. The influence of secondary effects, due to 
the poor tolerances achieved in the hand fabrication of the beam's assembly, are 
found to greatly affect the ability of the deflection analysis to give the required 
measured deflections. Comparison of the effective joint shear rigidities obtained 
from theory and testing indicates a higher individual connection stiffness in the 
prototype beam than previously determined by way of the individual Unistrut 
connector characterisation. 
It is found through the combined analytical and physical testing research that 
the M10 Unistrut connection method can only provide the necessary joint shear 
stiffness and resistance to the 400 mm deep beam if the connector spacing, along 
the four joints, is ≤ 50 mm. The total number of connectors this represents in the 
beam is likely to make this modular construction approach too expensive for it to 
be commercially viable. Although the M10 connector could be used to fabricate 
beams of lesser depths, since the number of connectors will then be reduced, these 
beams would find it difficult to compete with the available off-the-shelf PFRP 
beam shapes, of up to 300 mm deep. There is however scope to use the Unistrut 
method of connection to provide longitudinal shear resistance in building systems 
where, for example, a floor panel is to be stiffened by a channel shaped beam and 
the overall depth is ≤ 300 mm. 
The research work contained in this thesis has contributed to a radical change 
in the PFRP product offerings now proposed in the 2006 generation Startlink 
building system.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.