Comparative Analysis of Composite Box Girder Bridges Using Beam on Elastic Foundation (BEF) Method, Space Frame Method, Finite Element Method and Computer Programming

Abstract

Composite steel box girder superstructures are designed for almost any
span length and configuration but are particularly economic and
efficient for medium and long-span highway bridges. The primary
reason for the efficiency of steel boxes is their torsional stiffness.
However, the analysis of such sections is more complicated due to the
combination of flexure, shear, torsion, and distortion. In this study,
comparisons were made using a beam on elastic foundation, space
frame, finite element and java programming methods for analysing
these complications. The results obtained from this study include
deflections, transverse bending moments, longitudinal stresses and
shear flow with and without bracing under direct loading. The
numerical results of distortion at BEF and space frame were found to
be the same. Divergence was observed on comparison with the space
frame method, as the maximum percentage variation was 3.57% and
17.82% by falling into the range of 0.002m and 0.009m in distortion,
and 3.51% and 11.76% by falling into the range of 0.001MNm/m and
0.002MNm/m in transverse bending moments for computer
programming and finite element method respectively. Whereas there
was a full convergence (below 2%) with the space frame method as the
maximum percentage variation was 0.25% and 1.12% by falling into
the range of 0.33Mpa and 1.10Mpa in longitudinal warping stresses
for computer programming and finite element method respectively. The
results obtained also showed that the load distribution behaviour of the
structure was greatly improved when transverse bracing or framing
was introduced at positions along the box. The numerical results were
compared and validated to be in good agreement by falling within close
range of the different methods used. Thereby proving the viability and
workability of the methods developed and used.