Civil Engineering Reference
In-Depth Information
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Introduction
1.1 ADVANCEMENTS IN COMPOSITES
Fiber-reinforced polymer (FRP) composites are relatively new compared to conven-
tional construction materials. These composites are manufactured by combining small-
diameter fibers with polymeric matrix at a microscopic level to produce a synergistic
material. FRP composites have been considered in aerospace applications since the
mid-1950s, when they were used in rocket motor casings (Ouellete, Hoa, and Sankar
1986). Because of their light weight and design versatility, they have since entered struc-
tural systems in aerospace, automotive, marine, offshore drilling, and civil engineering
applications, in addition to sporting goods such as skiing equipment, commercial boats,
golf clubs, and tennis rackets (Jones 1975; Gibson 1994; ACI 440R-96 1996).
Typical structural elements made of advanced composites in fighter aircraft
include horizontal and vertical stabilizers, flaps, wing skins, and various control
surfaces, totaling weight savings of 20% (Gibson 1994). Other important structural
elements are helicopter rotor blades. As for the use of advanced composites in com-
mercial aircraft, they enter into the manufacturing of up to 30% of the external
surface area (Gibson 1994). However, currently they are only conservatively used in
secondary structures in large aircraft.
Advanced composites are used in a variety of additional industries as well.
Structural systems constructed of graphite/epoxy composites in space shuttles
include cargo bay doors and the solid rocket booster motor case (Gibson 1994).
Typical structural elements made of composites in the automotive industry include
leaf springs, body panels, and drive shafts (Gibson 1994). Typical pultruded struc-
tural shapes are used in lightweight industrial building construction to offer corrosion
and electrical/thermal insulation advantages. Another use of advanced composites in
civil engineering applications is in the building of lightweight, all-composite, hon-
eycomb-core decks for rapid replacement of short-span bridges (Kalny, Peterman,
and Ramirez 2004). Glass FRP (GFRP) reinforcing bars were produced using a pul-
trusion process created by Marshall Vega Corporation for use with polymer-based
concrete in the late 1960s (ACI 440R-96), and these bars continue to improve in
their characteristics, such as the addition of helically wound GFRP deformations for
enhanced bonding to concrete.
1.2 INFRASTRUCTURE UPGRADE
The transportation infrastructure in the United States and worldwide is aging due to
material deterioration and capacity limitations. Since complete rebuilding of such
infrastructure requires a huge financial commitment, alternatives of prioritized
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