Introduction - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 1

CHAPTER 1
Introduction
1.1 GENERAL REMARKS
Steel and steel-concrete composite bridges are commonly used all over the
world, owing to the fact that they combine both magnificent aesthetic
appearance and efficient structural competence. Their construction in a
country not only resembles the vision and inspiration of their architects
but also represents the country's existing development and dream of a better
future. Compared to traditional reinforced concrete (RC) bridges, steel
bridges offer many advantages, comprising high strength-to-self weight
ratio, speed of construction, flexibility of construction, flexibility to modify,
repair and recycle, durability, and artistic appearance. The high strength-to-
self weight ratio of steel bridges minimizes dead loads of the bridges, which is
particularly beneficial in poor ground conditions. Also, the high strength-to-
self weight ratio of steel bridges makes it easy to transport, handle, and erect
the bridge components. In addition, it facilitates very shallow construction
depths, which overcome problems with headroom and flood clearances, and
minimizes the length of approach ramps. Furthermore, high strength-to-self
weight ratio of steel bridges permits the erection of large components, and in
special circumstances, complete bridges may be installed in quite short
periods. The speed of construction of steel bridges is attributed to the fact
that most of the bridge components can be prefabricated and transported
to the construction field, which reduces working time in hostile environ-
ments. The speed of construction of steel bridges also reduces the durations
of road closures, which minimizes disruption around the area of construc-
tion. Flexibility of construction of steel bridges is attributed to the fact
that the bridges can be constructed and installed using different methods
and techniques. Installation may be conducted by cranes, launching,
slide-in techniques, or transporters. Steel bridges give contractors the flex-
ibility in terms of erection sequence and program. The bridge components
can be sized to suit access restrictions at the site, and once erected, the steel
girders provide a platform for subsequent operations. Flexibility to modify,
repair, and recycle steel bridges is a result of the ability to modify the current
status of the bridges such as widening the bridges to accommodate more
lanes of traffic. Also, steel bridges can be repaired or strengthened by adding