Approximate and refined analysis methods - Computational Analysis and Design of Bridge Structures - page 35

are different from the factors obtained for bridges with monolithic deck or
with transverse post-tensioning.

2.4.4 Finite strip method
A simplified finite element with bridge deck modeled end to end is called
inite strip (Figure 2.16). The displacement functions for in-plane and out-
of-plane deformation of the strip are of the form

n x
L

π

∑

w u v , , f y ( ) sin

= (2.10)

where:
x is the direction along the structure
y is the direction across the strip

The harmonic analysis is then performed. Further development on the finite
strip analysis extends to the curved circular structures with harmonic func-
tion (Fourier series) used for variations along circular arcs. As finite strip
method involves fewer nodes and a smaller matrix to solve, it is sometimes
more economical than other methods such as finite element. There are several
variations of finite strip method, semianalytical, spline, and boundary ele-
ment. The conventional finite strip method, because of its formulation, may
be very slow to converge with concentrated load and needs many series of
terms to achieve acceptable accuracy. With today's available computer speed
and memory, finite strip method is a plausible way to handle bridge problems.

Longitudinal
nodes

End
diaphragm
(a) (b)
Figure 2.16 Finite strip model. (a) Strip division of a box girder and (b) a closeup of strip
division of an I-girder.