Keywords: externally plated beams, side-plated beam, tension-face plated beam, longitudinal response, transverse response, slip, Reissner beam.

This paper presents a new mathematical model and its finite element formulation for the non-linear analysis of the mechanical behaviour of a constant cross-section planar beam strengthened with bolted plates or adhesively bonded plates to their sides. For the numerical solution of the stress-strain state of the structure a modified principle of virtual work is employed in formulating the finite element method. The basic unknowns of the problem are strains [1,2]. The following assumptions are adopted in the model: (i) for each layer (i.e. the beam and both of the side-plates) the geometrically linear and materially non-linear Bernoulli's beam theory is assumed, (ii) materials can in general differ from layer to layer, (iii) the debonding phenomena between the side-plate and the beam arising from, for example, a local buckling of the side-plate, is not possible. Regarding the connection of the beam to its side-plates at the interface, both, the longitudinal as well as the transversal partial interaction between layers are considered. The suitability of the theory is validated by the comparison of the numerical solution and experimental results by Su et al. [3] and Siu et al. [4]. A good agreement between both results is observed for any load level. There are more researchers for example [5,6] in the last few years reporting the good mechanical behaviour of side-plated beams in comparison to the alternative of tension-face plated beams. Also a comparison of the effects of these two positions of strengthening plates (side plates and tension-face plates) for two different contact connections (a stiff and a flexible connection) on the performance (ductility, bearing capacity and stiffness) of an externally strengthened RC beam is presented. In the case of the stiff connection a higher increase in the bearing capacity of the beam but a less ductile and a less flexible mechanical response is observed when the tension face strengthening plate is employed. When the connection is sufficiently flexible, the conclusions are just the opposite. Here a better strength enhancement, smaller vertical displacements and a higher rate of loss in ductility of the structural response are observed in the case of the side-plated beam. We conclude that side plates can efficiently enhance the bearing capacity of flexural beams and can, in some cases, over perform the alternative tensile-face strengthening plates in a lower rate in the loss of ductility, especially when the interlayer connection is sufficiently stiff.

1

B. Cas, M. Saje, I. Planinc, "Non-linear finite element analysis of composite planar frames with an interlayer slip", Computers and Structures, 82(23-26), 1901-1912, 2004. doi:10.1016/j.compstruc.2004.03.070

2

B. Cas, M. Saje, I. Planinc, "Non-linear analysis of composite steel-concrete beams with incomplete interaction", Steel Composite Structures, 4(6), 489-507, 2004b.

3

R.K.L. Su, W.H. Siu, S.T. Smith, "Effects of bolt-plate arrangements on steel plate strengthened reinforced concrete beams", Engineering Structures, 32(6), 1769-1778, 2010. doi:10.1016/j.engstruct.2010.02.028

4

W.H. Siu, R.K.L. Su, "Effects of plastic hinges on partial interaction behaviour of bolted side-plated beams", Journal of Constructional Steel Research, 66(5), 622-633, 2010.

5

I.S.T. Liu, D.J. Oehlers, R. Seracino, "Tests on the ductility of reinforced concrete beams retrofitted with FRP and steel near surface mounted plates", Journal of Composites for Constructions, 10(2), 106-114, 2006. doi:10.1061/(ASCE)1090-0268(2006)10:2(106)

6

N.T. Nguyen, D.J. Oehlers, M.A. Bradford, "An analytical model for reinforced concrete beams with bolted side plates accounting for longitudinal and transverse partial interaction", International Journal of Solids and Structures, 38(38-39), 6985-6996, 2001. doi:10.1016/S0020-7683(01)00036-1

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 £130 +P&P)