Keywords: corrugated web, accordion effect, composite structure, prestressed concrete, finite element analysis.

Prestressed concrete box girders with corrugated steel webs are one of the promising concrete-steel hybrid structures applied to highway bridges [1,2]. The decreased dead weight of corrugated steel web, compared to concrete web, leads to reduced seismic forces and smaller substructures, which will result in a lower construction cost of the bridge. The corrugated steel webs have a higher shear-buckling strength than flat plate steel webs. Prestress can be efficiently introduced into the top and bottom concrete flanges due to the so-called "accordion effect" of corrugated webs. The accordion effect is a rather complicated three-dimensional (3-D) phenomenon including both the in-plane and out-of-plane deformations of the corrugated web.

In this paper a simple approach is presented to account for the 3-D accordion effect within a two-dimensional finite element analysis, with attention towards a design of the new type of concrete-steel hybrid structures. In the 2-D modelling of the corrugated steel web, each of the inclined panel plate is cut vertically along its centre line and is replaced by two horizontal plates with a reduced length and an equivalent thickness. 2-D zero-size link elements are then inserted connecting the nodes of two separated steel elements, to model the accordion effect of the corrugated steel web. In the horizontal direction, the link stiffness is given a value calculated from the out-of-plane bending of each trapezoidal corrugation. In the vertical direction, however, links are given a very high stiffness to fully transmit vertical shear force. Thus the accordion effect developed continuously in the corrugated steel web is lumped into the horizontal link springs.

Three types of elements are used in the analysis: 1) plane stress elements represent both the concrete continuum and the steel web, 2) 1-D truss elements represent the upper and lower steel flanges welded to the corrugated web and the reinforcing bars in the concrete flanges, and 3) link elements model the accordion effect of the corrugated web. Viability of the approach is demonstrated through comparison of experimental and numerical results for a large scale specimen of a prestressed concrete beam with corrugated steel web, which was tested by Ata et al. [3]. The following conclusions are made concerning the modelling used in this research and its application to hybrid PC beams.

1. The proposed 2-D modelling was successful in representing the 3-D accordion effect of corrugated steel webs on the deflection curve, strains induced by prestressing, and the strain distribution under vertical loadings.
2. The use of corrugated steel webs has a strong effect on the distribution of axial strain over the web due to its accordion effect. That is, the axial strain decreases rapidly to zero over the central portion of the web, although the concentration of strain in the web local to the upper and lower flanges is witnessed in both the test and the analysis.
3. Flexural rigidity of the hybrid PC beam is not affected very much by the accordion effect of the corrugated steel web. However, an appreciable error is introduced into its deflection calculated by elementary beam theory neglecting the shear deformation of steel web, due to the large flexural rigidity and rather small web area of the hybrid PC beam.
4. The web stiffening provided by a cross-frame or a diaphragm is highly effective for restricting the local accordion effect of the corrugated web nearby a concentrated load.

1

Combault, J., Lebon, J.D., Pei, G., "Box-Girders Using Corrugated Steel Webs and Balanced Cantilever Construction", in "Proceedings of the FIP Symposium '93", Kyoto, 417-424, 1993.

2

Yamaguchi, K., Yamaguchi, T., Ikeda, S., "The Mechanical Behaviour of Prestressed Concrete Girders with Corrugated Steel Webs", Concrete Research and Technology, Vol. 8, No.1, 27-41, 1997.

3

A ta, Y., Ochiai, M., Mizoe, Y., Machida, F., "Static and Fatigue Test of Beam Specimens for Prestressed Concrete Bridge with Corrugated Steel Web", Prestressed Concrete Journal, Japan, Vol.43, No.4, 72-81, 2001.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £125 +P&P)