Andrew Wheeler

Measured imperfections in six thin-walled steel tubes

Abstract The structural behaviour of thin-walled members is often extremely imperfection sensitive. For many types of such members only little information of the exact nature of the present imperfections is available. A method of measuring imperfections of circular cylindrical members has been developed and was used to measure six thin-walled tubes. The method is simple to implement in a laboratory environment yet very accurate. Numerical methods to process the measurements into three-dimensional imperfection maps and an algorithm to distinguish between significant imperfection patterns from measurement “noise” have been derived. Results of the measurement of these six tubes are presented in this paper. Conclusions about the nature of the imperfections are drawn and imperfection amplitudes for the six tubes are given.

A New Design Proposal for Secondary Composite Beam Shear Connections Incorporating Trapezoidal Steel Decking

Abstract An extensive experimental program was undertaken to investigate the behaviour of secondary composite beam shear connections incorporating trapezoidal steel decking. Based on the test results, a new design proposal to determine the shear connection strength was developed, which also incorporates the application of stud reinforcing devices that have been found to significantly improve the behaviour of the shear connection. The new proposal has been coupled with a reliability analysis that has been calibrated to provide a safety index similar to stud applications currently in use. Simple strength reduction factors for the types of trapezoidal steel decking available in Australia are presented, and can be applied to the current shear connection strength as given in AS 2327.1 (Standards Australia, 2003) for a fast and simplified design.

Strength of headed stud shear connection in composite beams

Abstract The paper summarises the results of an extensive review of various push-out test series in order to determine the mean strength of headed stud shear connectors in solid slab applications. It also investigates the influence that different test set-ups can have on the connector strength. Based on the findings, an analysis of previous test series of stud shear connection incorporating trapezoidal steel decking is undertaken which indicates the unreliable and unconservative nature of the reduction factor approach.

Behaviour and design of webs in high strength steel under flexural loading

Publisher Summary The flexural behavior of steel beam sections subjected to flexural loading is studied extensively in the chapter, and detailed design methods are developed. The chapter presents a number of experiments carried out to investigate the flexural behavior of webs in high-strength steel beams. An experimental program is conducted to study the behavior of webs in beams subjected to flexure using sections constructed of high-strength steel with nominal yield strength of 690 MPa. The results are compared with the relevant design provisions in the current Australian steel structures standard. The slenderness of the webs is varied to investigate compact and non-compact sections and sections approaching slender as defined in the standard. The experimental program demonstrated that the prescribed plastic and elastic limits for webs in the Australian Steel Structures Standard AS 4100-1998 are appropriate for high strength steel.

Membrane imperfections measured in cold formed tubes

The use of concrete filled steel tubes in the construction industry continues to increase as an economic alternative to traditional construction methods. This paper presents a new method for measuring and analyzing the imperfections of cylindrical members. The method is simple to implement in a laboratory environment yet very accurate. From the measurement results, three-dimensional imperfection maps for the measured tubes were produced. In producing the maps, a method of analysis is applied to filter out any noise and the presence of any repetitive imperfections possibly caused by the manufacturing process assessed. To assist with future research the results are assessed using a Fourier analysis coupled with cross validation, to determine the dominant Fourier terms.

Effect of concrete infill on non-compact tubes subjected to pure bending

Publisher Summary The use of concrete filled thin walled steel tubes in structural applications is widespread, particularly for axially loaded members. While extensive experimental studies is carried out on tubes subjected to primarily axial loads, some with limited eccentricities, few studies are carried out into the flexural behavior of such members. This chapter presents the results from a testing program carried out at the University of Western Sydney. The program is designed to demonstrate the effect of the concrete in-fill on the flexural behavior of the tubes, and will be used as a basis for developing design rules for concrete filled tubes subjected to flexure. Parameters hat are investigated include the diameter to wall thickness ratio and concrete strength. Comparisons are made with identical tests carried out on bare steel tubes. The chapter has described a test program on the behavior of both bare steel and concrete filled large diameter thin walled sections subjected to flexural loading. A detailed description of the test procedure and results has been presented. The tests clearly demonstrated that the behavior of the tube, when filled with concrete, is enhanced. The ultimate strength of the sections is increased by over 20%. The ductility of the section is also increased with deflections exceeding four times those measured for the bare steel tubes.

Flexural Behaviour of Concrete-Filled Thin-Walled Steel Tubes with Longitudinal Reinforcement

Concrete filled steel tubes (CFTs) are efficient members in structural applications including bridges, buildings and piled foundations and their use in the building industry is increasing. To date their primary use has been in axial applications, with the design methodology based on theory and tests of columns under loads applied axially or at relatively small eccentricities. Limited in to research into the behaviour of CFTs subjected to large eccentricities or loading in pure flexure have been conducted, with preliminary experimental investigation suggesting that stiffness of composite members tending towards that of the tube at relative low loads. An ongoing research program on the flexural behaviour of CFTs is being undertaken at the University of Western Sydney with a particular emphasis on thin-walled steel tubes that can provide an economical form of construction. In this paper, the results from additional experimental work will be presented with a particular emphasis on the stiffness of the members when subjected to flexural loading. The experimental work to date has demonstrated that even in composite specimens where there is negligible end slip; the stiffness of the specimens under pure flexure tends to the stiffness of the bare steel tube. A numerical model will also be presented that can accurately generate the bond/slip relationship of the concrete within the steel tubes and consequently the behaviour of the specimens modelled. From the experimental results and the numerical model some guidelines for the design of concrete filled tubes subjected to primarily flexural loading will be presented.