Steel Plate Elements Research Articles

Local buckling behaviour and design of profiled sandwich panels

Fully profiled sandwich panels are commonly used in building structures, but are susceptible to local buckling failures. Current European design standard recommends the use of a modified effective width approach to include such local buckling effects in the design. Recent research has shown that this design method predicts unconservative strengths for panels with slender plates (high b/t ratios). The use of sandwich panels with high b/t ratios is very common in practice due to the increasing use of thinner and high strength steel plates. Therefore, a research project was conducted to investigate the local buckling behaviour of foam supported steel plate elements as used in fully profiled sandwich panels with a large range ofb/t ratios (50 to 500) using experiments and finite element analyses (FEA). Both experimental and FEA results revealed the inadequacy of the current design rule for sandwich panels with slender plate elements. An improved design method was therefore developed based on the large amount of data obtained from validated FEA studies. Finally full-scale tests of fully profiled sandwich panels were undertaken to confirm the accuracy of the new design method. This paper presents an overview of these experimental and finite element analysis studies and design rule development followed by the results of the full-scale tests.

Ultimate compressive strength of plate elements with pit corrosion wastage

The aim of the present paper is to investigate the ultimate strength characteristics of plate elements with pit corrosion wastage under axial compressive loads. Collapse tests on a box column type of steel-plated structures with different degrees of pit corrosion damage are undertaken. A series of ANSYS non-linear finite element analyses for steel plate elements under axial compressive loads are carried out, varying the degree of pit corrosion intensity and plate geometric properties. In this paper, a new parameter, i.e. the smallest cross-sectional area, is proposed to represent the ultimate strength reduction characteristics due to localized corrosion. It is proved that the proposed parameter-based approach is more useful than the traditional approach based on equivalent thickness in terms of the accuracy of ultimate strength predictions of pitted plates. Closed-form design formulae for the ultimate compressive strength of pitted plates, which are needed for the ultimate limit state-based risk or reliability assessment of corroded structures, are derived by regression analysis of the experimental and numerical results obtained from the present study. The insights developed will be very useful for the damage-tolerant design of plated structures with pit corrosion damage.

Finite element analysis and design of sandwich panels subject to local buckling effects

Past research into the local buckling behaviour of fully profiled sandwich panels has been based on polyurethane foams and thicker lower grade steels. The Australian sandwich panels use polystyrene foam and thinner and high strength steels, which are bonded together using separate adhesives. Therefore a research project on Australian sandwich panels was undertaken using experimental and finite element analyses. The experimental study on 50 foam-supported steel plate elements and associated finite element analyses produced a large database for sandwich panels subject to local buckling effects, but revealed the inadequacy of conventional effective width formulae for panels with slender plates. It confirmed that these design rules could not be extended to slender plates in their present form. In this research, experimental and numerical results were used to improve the design rules. This paper presents the details of experimental and finite element analyses, their results and the improved design rules.

Experimental investigation and design of sandwich panels subject to local buckling effects

The use of sandwich panels in Australia has increased significantly in recent years due to their widespread structural applications in building systems. Structural sandwich panels generally used in Australia comprise of polystyrene foam core and thinner and high strength steel faces. The fully profiled sandwich panels, when subjected to axial compression and/or bending effects, are susceptible to local buckling failures. A research project was undertaken using a detailed experimental study on 50 foam supported steel plate elements to investigate the local buckling and postbuckling behaviour of sandwich panels and to examine the adequacy of currently used effective width approach for design. Experimental results have revealed that the current method is adequate for the steel plate elements with low b/t ratios. However, it appears to be inadequate for the plate elements with higher b/t ratios (slender plates). This paper presents the details of the experimental studies on polystyrene foam supported steel plates, the results, and the evaluation of current design rules for profiled sandwich panels subject to local buckling effects.

Local buckling behaviour of steel plate elements supported by a plastic foam material

Sandwich panels comprising steel facings and a polystyrene foam core are increasingly used as roof and wall claddings in buildings in Australia. When they are subjected to loads causing bending and/or axial compression, the steel plate elements of their profiled facing are susceptible to local buckling. However, when compared to panels with no foam core, they demonstrate significantly improved local buckling behaviour because they are supported by foam. In order to quantify such improvements and to validate the use of available design buckling stress formulae, an investigation using finite element analyses and laboratory experiments was carried out on steel plates that are commonly used in Australia of varying yield stress and thickness supported by a polystyrene foam core. This paper presents the details of this investigation, the buckling results and their comparison with available design buckling formulae.

Openings in Thin-Walled steel structures

A review is made of the research work that has been carried out to date to account for the effects of openings on the behaviour of thin-walled elements in steel structures. Attention is directed to relatively thin steel plate elements typical of those that occur in plated structures. Plate elements that are subjected to uniaxial compression or biaxial compression or shear loading, stiffened plates, shear webs and cold formed steel sections are considered separately. Analytical and experimental work carried out on centrally or eccentrically placed, reinforced or unreinforced circular or rectangular openings are considered in the review. Design methods of thin-walled steel structural elements that account for the presence of openings are highlighted.

A DESIGN METHOD OF STEEL PLATE ELEMENTS IN CONCRETE FILLED SQUARE STEEL TUBULAR COLUMNS

In this paper, the ultimate strength of steel plate elements in the concrete filled square steel tubular columns is analyzed by using the F. E. M. based on the elastoplastic and large displacement theory. It is found through numerous parametric analyses that the influence of restrictions due to the concrete core upon the boundary conditions concerning the in-plane displacement of the steel plate element along the unloaded edges is tought to be negligible in an ordinary composite column. Furthermore, it is difficult to prevent the local buckling of steel plate elements by the shear connectors, even when they are sufficiently welded on the plate elements and anchored into the concrete core. A tentative design method is proposed by adopting a simplified ultimate strength curve and a column model approach using an effective stiffener which consists of a plate element and a longitudinal stiffener for unstiffend and stiffened steel plate elements, respectively.

Elasto-plastic analysis of orthogonally stiffened plates with initial imperfections under uniaxial compression

In general, the stiffened plates consisting of steel plate elements are unavoidably accompanied by initial imperfections such as residual stresses and initial deflections, which have considerable effects on their ultimate strength. Therefore, it is needed for designing them to develop more rational method taking the ultimate strength influenced by initial imperfections into account rather than the conventional design method being on the basis of the linear elastic buckling theory. From this point of view, this study aims to evaluate rigorously the ultimate strength of orthogonally stiffened plate with initial imperfections under uniaxial in-plane compression. The elasto-plastic finite element method is applied to attain this purpose. By a happy combination of modal analytical technique and conventional finite element method, much reduction of the degree of freedom can be expected to be realized herewith. Some numerical calculations are performed by means of this rigorous method to examine the exactness of the analysis. Moreover, the numerical results are compared with the experimental ones.