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CONTENTS
Volume 3, Number 6, December 2003
 

Abstract
Two new formulae for the design of beam-columns at room temperature have been proposed into Eurocode 3, prEN 1993-1-1 (2002), and are the result of great efforts made by two working groups that followed different approaches, a French-Belgian team and an Austrian-German one. Under fire conditions thernprEN 1993-1-2 (structural fire design) presents formulae, for the design of beam-columns based on the prENV 1993-1-1 (1992). In order to study the possibility of having, in part 1-1 and part 1-2 of the Eurocode 3, the same approach, a numerical research was made using the finite element program SAFIR, developed at the University of Liege for the study of structures subjected to fire.rn

Key Words
beam-column; buckling; lateral-torsional-buckling; fire; Eurocode 3; numerical modelling.

Address
P.M.M. Vila Real, N. LopesrnDepartment of Civil Engineering, University of Aveiro, 3810 Aveiro, PortugalrnrnL. Simoes da SilvarnDepartment of Civil Engineering, University of Coimbra, 3030-290 Coimbra, PortugalrnrnP. PilotornDepartment of Mechanical Engineering, Polytechnic of Braganca, Braganca, PortugalrnrnJ.-M. FranssenrnDepartment M&S, University of Liege, Liege, Belgium

Abstract
In the paper one investigates the benefits deriving from the introduction of SMA provisions in a structure subject to dynamic excitation and vertical loads. At this purpose one considers a multi-degree-offreedom(mdof) shear elastic-plastic frame and designs couples of super-elastic SMA tendons to be placed at critical locations of the structure. Particular attention is focused on the reduction of P-Δ effects.

Key Words
structural dynamics; smart materials; semi-active devices; shape memory alloys.

Address
University of Naples Federico II, Dept. Scienza delle Costruzioni, via Claudio 21, 80125, Naples, Italy

Abstract
Aging and deterioration of existing steel structures necessitate the development of simple and efficient rehabilitation techniques. The current study investigates a methodology to enhance the flexural capacity of steel beams by bonding Glass Fibre Reinforced Plastic (GFRP) sheets to their flanges. A heavy duty adhesive, tested in a previous study is used to bond the steel and the GFRP sheet. In addition to its ease of application, the GFRP sheet provides a protective layer that prevents future corrosion of the steel section. The study reports the results of bending tests conducted on a W-shaped steel beam before and after rehabilitationrnusing GFRP sheets. Enhancement in the moment capacity of the beam due to bonding GFRP sheet is determined from the test results. A closed form analytical model that can predict the yield moment as well as the stresses induced in the adhesive and the GFRP sheets of rehabilitated steel beam is developed. A detailed finite element analysis for the tested specimens is also conducted in this paper. The steel web and flanges as well as the GFRP sheets are simulated using three-dimensional brick elements. The shear and peel stiffness of the adhesive are modeled as equivalent linear spring systems. The analytical and experimental rnresults indicate that a significant enhancement in the ultimate capacity of the steel beam is achieved using the proposed technique. The finite element analysis is employed to describe in detail the profile of stresses and strains that develop in the rehabilitated steel beam.

Key Words
rehabilitation; steel beams; glass fibre reinforced plastic; experimental; finite element; analytical model.

Address
Dept. of Civil and Environmental Engineering, The University of Western Ontario, London, ON, Canada, N6A 5B9rn

Abstract
The finite strip transition matrix technique, a semi analytical method, is employed to obtain the buckling loads and the natural frequencies of symmetric cross-ply laminated composite plates with edges elastically restrained against both translation and rotation. To illustrate the accuracy and the validation of thernmethod several example of cross play laminated composite plates were analyzed. The buckling loads and the frequency parameters are presented and compared with available results in the literature. The convergence study and the excellent agreement with known results show the reliability of the purposed technique.

Key Words
buckling; vibration; finite strip; elastic restraint; laminated plates.

Address
Faculty of Engineering, International Islamic University Malaysia, 53100 Kuala Lumpur, Malaysia

Abstract
Details are given of a cold-formed steel portal framing system that uses simple bolted momentconnections for both the eaves and apex joints. However, such joints function as semi-rigid and, as a result, the design of the proposed system will be dominated by serviceability requirements. While serviceability is a mandatory design requirement, actual deflection limits for portal frames are not prescribed in many of the national standards. In this paper, a review of the design constraints that have an effect on deflection limits is discussed, and rational values appropriate for use with cold-formed steel portal frames are recommended.rnAdopting these deflection limits, it is shown through a design example how a cold-formed steel portal frame having semi-rigid eaves and apex joints can be a feasible alternative to rigid-jointed frames in appropriate circumstances.

Key Words
cold-formed steel portal frames; deflection limits; finite connection-length; semi-rigid joints; serviceability requirements.

Address
J.B.P. LimrnThe Steel Construction Institute, Silwood Park, Ascot, Berkshire SL5 7QN, UKrnD.A. NethercotrnImperial College, London, UK


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