a b s t r a c tThis paper presents the optimisation of cold-formed steel open columns using the recently developed self-shape optimisation method that aims to discover new profile shapes. The strength of the coldformed steel sections is calculated using the Direct Strength Method, and the rules developed in the present work to automatically determine the local and distortional elastic buckling stresses from the Finite Strip and constrained Finite Strip Methods are discussed. The rules are verified against conventional and optimum sections yielded in this research, and found to accurately predict the elastic buckling stresses. The optimisation method is applied to singly-symmetric (mono-symmetric) cold-formed steel columns, and the operators behind the method for the special case of singlysymmetric open profiles are introduced in this paper. ''Optimum'' cross-sections for simply supported columns, 1.2 mm thick, free to warp and subjected to a compressive axial load of 75 kN are presented for column lengths ranging from 1000 to 2500 mm. Results show that the optimum cross-sections are found in a relatively low number of generations, and typically shape to non-conventional ''bean'', ''oval'' or rounded ''S'' sections. The algorithm optimises for distortional and global buckling, therefore likely subjecting the cross-sections to buckling interaction. A manual attempt to redraw the ''optimum'' cross-sections to include limitations of current manufacturing processes is made. Future developments of the method for practical applications are also discussed.

Australia's utility pole network is aging and approaching its end of life. It is estimated that 70% of the 5 million poles currently in-service nationally were installed within the 20 years following the end of World War II and require replacement or remedial maintenance. Additionally, an estimated 21,700 high-durability new poles are required each year to support the expansion of the energy network. Utility poles were traditionally cut from native forest hardwood species. However, due to agreements which progressively phase out logging of native forests around Australia, finding new sources for utility poles presents a challenge. This paper presents the development of Veneer Based Composite hardwood hollow utility poles manufactured from mid-rotation Gympie messmate (Eucalyptus cloeziana) plantation thinned trees (also referred to as "thinning"), as an alternative to solid hardwood poles. The incentives behind the project and benefits of the proposed products are introduced in the paper. Small diameter poles, of nominal 115 mm internal diameter and 15 mm wall-thickness, were manufactured in two half-poles butt jointed together, using 9 hardwood veneers per half-pole. The poles were tested in bending and shear, and experimental test results are presented. The mechanical performance of the hollow poles is discussed and compared to hardwood poles sourced from mature trees and of similar size. Additionally, the required dimensions of the proposed hollow pole to replace actual solid poles are estimated. Results show that the proposed product represents a viable technical solution to the current shortage of utility poles. Future research and different options for improving the current concept are proposed in order to provide a more reliable and cost effective product for structural and architectural applications in general.

For economical benefits, optimisation of mass-produced structural steel products has been widely researched. The objective is to minimise the quantity of material used without sacrificing the strength and practicality of the structural members. Current research focuses on optimising the main dimensions of conventional cross-sectional shapes but rarely considers discovering new optimum shapes. This paper introduces the concepts of a new optimisation method that enables the crosssection to self-shape to an optimum by using the evolution and adaptation benefits of Genetic Algorithm (GA). The feasibility and accuracy of the method are verified by implementing it to optimise the section capacity of thin-walled profiles. Specifically, the profiles are optimised against simple parameters for which analytical solutions are known, namely the optimisation of doublysymmetric closed profiles. Results show that the cross-section accurately self-shapes to its optimum in a low number of generations. Factors influencing the convergence are presented in this paper. The method is extended to optimisation of cold-formed steel open section columns in the companion paper.

Reinforced concrete (RC) flat-plate structures are vulnerable to punching shear failure at their slab-column connections, potentially leading to a catastrophic progressive collapse. In practice, the slab-column connection above an interior column, removed due to abnormal loads, may be subjected to a concentrated downward force due to the absence of the supporting column and further being pushed due to different live load intensities on individual stories. This force is different to the full design load that the column withstands in normal situation and, combined to the gravity load acting on the slab, may cause punching shear failure at the interior slabcolumn connection. This will further trigger failure propagation to the surrounding slab-column connections. This paper presents the experimental tests performed on two identical large scale 2×2-bay RC flat-plate specimens under an interior column removal scenario. A 5 kPa uniformly distributed load was applied first to the slab followed by an incremental concentrated force imposed on the slab-column connection above the removed interior column. The complete collapse resistant behavior and load redistribution pattern of the specimens were investigated and are reported herein. Results show that more than 90% of the applied concentrated force is solely distributed to the four nearest adjacent columns. Three load carrying mechanism phases, in form of flexural, tensile membrane, and a combination of one-way catenary and dowel actions can be distinguished in resisting the applied concentrated load.

This paper experimentally investigates the mechanical properties of rotary veneers peeled from small-diameter hardwood plantation logs, recovered from early to mid-rotation subtropical hardwood plantations. The study aims at providing essential probabilistic data needed to ultimately predict the capacity and reliability of veneered based composites structural products (such as LVL and plywood) from characteristics which can be measured in line during manufacturing. Two species planted for solid timber end-products (Gympie messmate-Eucalyptus cloeziana and spotted gum-Corymbia citriodora) and one species traditionally grown for pulpwood (southern blue gum-Eucalyptus globulus) were studied. The compressive and tensile Modulus of Rupture (MOR) of the veneers, parallel to the grain and for veneer based composite applications, were experimentally investigated. Results show that the compressive MOR for all species typically ranges from 30-50 MPa (for MOE < 12,000 MPa) to 60-90 MPa (for MOE > 22,000 MPa). The tensile MOR is typically lower than or in the range of the compressive MOR for MOE less than 12,000 MPa, while for larger MOE (MOE > 22,000 MPa), tensile MOR greater than 140 MPa were observed. The total knot area ratio (tKAR) of the veneers is also analysed and Weibull distributions were found to provide a good characterisation of the statistical repartition of the tKAR value along the length of a veneer sheet. For each species, equations to best predict a veneer MOR from its measured MOE and tKAR value are derived and fit the experimental results with a coefficient of determination between 0.63 and 0.74. The variability of the MOR of each species was accurately modelled by Weibull distributions, with the distribution parameters determined based on the experimental data. Results shown that southern blue gum and Gympie messmate is the most and least sensitive species to size effects.