Keywords: composite, curved, non-linear, shrinkage, viscoelastic.

A computational modelling procedure for bridge beams curved in-plan is presented in the paper. When the bridge beam is composite with a concrete deck and a steel girder that are connected by mechanical headed stud shear connectors, predicting the deformations is complicated, and this complication is exacerbated when the inevitable shrinkage and creep of the concrete slab are included [1]. Under service loading (typically up to 40% of the compressive strength of the deck), linear viscoelastic material modelling is sufficiently accurate to model creep effects, which can be characterised by the fact that the rate at which the inelastic strains develop depends not only on the current state of the stress and strain, but also on the full history of their development. To this end, shrinkage and creep of the deck are included by using a Maxwell-Wiechert representation [2]. Because of the presence of combined primary bending and torsion, the behaviour of curved members is fundamentally different to that of straight members, with research on the topic being comparatively recent when creep and shrinkage are included.

Since much contemporary bridge infrastructure is reliant on predicting very close tolerances to enable high speed travel, a model incorporating these aspects in curved bridges is much needed, and so the technique proposed includes a curved steel girder, curved concrete deck, partial interaction between the deck and girder in both the longitudinal and the radial directions, geometric non-linearity and shrinkage and creep of the deck. Geometric non-linearity is handled by an a priori statement of the strain-displacement relationships derived from the geometry of the deformation of the bridge girder. Virtual work equations are established at two infinitesimally adjacent times in the time history of the bridge, and their difference leads to the tangent stiffness relationships, whose solution is expedited using a Newton-Raphson procedure.

The formulation developed is shown to provide a very efficient technique. Representative examples are considered in the paper to illustrate the effects of initial curvature, partial interaction and geometric non-linearity on the time-dependent behaviour of composite beams curved in-plan.

1

M.A. Bradford, R.I. Gilbert, "Composite Beams with Partial Interaction under Sustained Loads", Journal of Structural Engineering, ASCE 118(7), 1871-1883, 1992. doi:10.1061/(ASCE)0733-9445(1992)118:7(1871)

2

Z.P. Bazant, S.T. Wu, "Rate-type Creep Law of Aging Concrete Based on Maxwell Chain", Materials and Structures, 7(37), 45-60, 1974. doi:10.1007/BF02482679

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 £145 +P&P)