Civil Engineering Reference
In-Depth Information
1.5 CURRENT DESIGN CODES OF STEEL AND
STEEL-CONCRETE COMPOSITE BRIDGES
Design rules and specifications are proposed in different countries to define
standards and methods of analysis of steel and steel-concrete composite brid-
ges. The design guides are commonly based on experimental investigations
on small-scale bridges and small/full-scale bridge components. Many design
formulas specified in current codes of practice are in the form of empirical
equations proposed by experts in the field of bridges. However, the empir-
ical equations only provide guidance for design of the bridges and their com-
ponents in the ranges covered by the specifications. The ranges covered by
the specification depend on the number of tests conducted on the bridges at
the time of proposing the codes. Since there is continuing progress in
research to discover newmaterials, sections, connections, and different load-
ings, the codes of practice need to be updated from time to time. Further-
more, test programs on steel and steel-concrete bridges and their
components are dependent on the limits of the test specimens, loading,
boundary conditions, and so on. Therefore, the design equations specified
in current codes of practice always have limitations. Finite element analysis
can provide a good insight into the behavior of steel and steel-concrete com-
posite bridges outside the ranges covered by specifications. In addition, finite
element analysis can check the validity of the empirical equations for sections
affected by nonlinear material and geometry, which may be ignored in the
specifications. Furthermore, design guides specified in current codes of prac-
tice contain some assumptions based on previous measurements, for exam-
ple, assuming values for initial local and overall imperfections on the bridge
beams and compression members. Also, finite element modeling can inves-
tigate the validity of these assumptions. As mentioned previously, an exam-
ple of the shortcomings in current codes of practice for steel-concrete
composite bridges is that, up-to-date, there are no design provisions to con-
sider the actual load-slip characteristic curve of the shear connectors used in
the bridges, which results in partial degree of composite action behavior.
This topic will detail, for the first time, how to consider the correct and
actual slip occurring at the steel-concrete interface in composite bridges
through finite element modeling. This topic addresses the efficiency of finite
element analyses and the numerical results are able to improve design equa-
tions in the current codes of practice more accurately. However, it should be
noted that there are many specifications developed all over the world for
steel and steel-concrete composite bridges. It is not the intention to include
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