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• The compressive behaviour of square RACFSST stub columns after exposure to fire is investigated. • Twelve post-fire compression tests are conducted. • The influences of heating durations and RCA replacement ratios are discussed. • Thermal and mechanical FE models are validated against test results and then used to conduct parametric studies. • The relevant design codes are assessed against the test and FE data. Experimental and numerical studies on the cross-section compressive behaviour and residual resistances of square recycled aggregate concrete-filled stainless steel tube (RACFSST) stub columns after exposure to fire are reported in this paper. An experimental programme was firstly carried out on twelve stub column specimens with three recycled coarse aggregate replacement ratios (0%, 35% and 70%) after exposure to the ISO-834 standard fire for 0 min (i.e. at ambient temperature), 15 min, 30 min and 45 min. The test results, including load–end shortening curves, failure loads and failure modes, were presented, with the initial compressive stiffness and confinement effect analysed. The experimental programme was followed by a numerical modelling programme, where thermal and mechanical finite element models were developed and validated against the test results and afterwards used to conduct parametric studies to generate additional numerical data over a wide range of cross-section dimensions. Based on the test and numerical data, the relevant design rules for square natural aggregate concrete-filled carbon steel tube stub columns at ambient temperature, as specified in the European code, Australia/New Zealand standard and American specification, were evaluated, using post-fire material properties, for their applicability to square RACFSST stub columns after exposure to fire. The evaluation results generally revealed that the European code and Australian/New Zealand standard led to a good level of design accuracy, while the American specification resulted in slightly conservative post-fire cross-section compression resistance predictions. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical investigations into the post-fire cross-section compressive behaviour and resistances of circular recycled aggregate concrete-filled stainless steel tube (RACFSST) stub columns. Twelve stub column specimens, fabricated from concretes with three recycled coarse aggregate replacement ratios (0%, 35% and 70%), were tested after exposure to the ISO-834 standard fire for 0 min (i.e. at ambient temperature), 15 min, 30 min and 45 min. The experimental investigation included heating and cooling of specimens, cylinder tests and post-fire tensile coupon tests and stub column tests. The test results, including load–end shortening curves, failure loads and failure modes, were fully reported and the initial compressive stiffnesses and confinement effect were discussed. The numerical investigation was subsequently conducted, where thermal and mechanical finite element models were developed and validated against the test results and then used to perform parametric studies to generate further numerical data. Given the absence of design codes for stainless steel–recycled aggregate concrete composite structures after exposure to fire, the relevant design rules for circular natural aggregate concrete-filled carbon steel tube stub columns at ambient temperature, as set out in the European code, Australia/New Zealand standard and American specification, were assessed, using post-fire material properties, for their applicability to circular RACFSST stub columns after exposure to fire, based on the test and numerical data. The assessment results generally revealed that the European code and the Australian/New Zealand standard led to an acceptable level of design accuracy and consistency, while the American specification resulted in rather conservative and scattered post-fire cross-section compression resistance predictions. • The compressive behaviour of circular RACFSST stub columns after exposure to fire is investigated. • Post-fire compression tests on twelve circular RACFSST stub column specimens are conducted. • The influences of heating durations and RCA replacement ratios are analysed. • Thermal and mechanical FE models are validated against test results and then used to conduct parametric studies. • The relevant design codes are assessed against the test and FE data. [ABSTRACT FROM AUTHOR]

Cold-formed steel sections are used in many different shapes based on their applications. Recently, a new C-section known as SupaCee was introduced in Australia with higher flexural capacities compared to traditional channel sections. However, all cold-formed steel sections are vulnerable to web crippling failures due to their higher plate slenderness. Australian/New Zealand (AS/NZS 4600) and North American (AISI S100) Standards use a unified web crippling design equation with four coefficients while Eurocode 3 Part 1.3 uses different design equations to predict the web crippling capacities of cold-formed steel sections. The web crippling coefficients were developed based on the experimental studies undertaken since the 1940s. These experimental studies utilised different test set-ups and specimens lengths and hence the accuracy of predictions using these coefficients may be inadequate. No coefficients are available for unlipped channel sections with fastened supports and high strength SupaCee sections while the same coefficients are used for lipped channels with fastened and unfastened supports. To address these shortcomings, the web crippling behaviour of unlipped and lipped channel and SupaCee sections was experimentally investigated based on recently developed AISI S909 web crippling test guidelines. Finite element analyses were then performed to extend the range of cold-formed steel sections. Using the web crippling capacity results from both experiments and finite element analyses, new equations were proposed to determine the web crippling capacities of lipped and unlipped channel and SupaCee sections. Suitable direct strength method based web crippling design equations were also developed. This paper presents the important details of several detailed web crippling studies undertaken recently including a suite of web crippling design equations that can be adopted in relevant cold-formed steel standards. • Investigated web crippling behaviour of several cold-formed steel sections. • Developed advanced finite element models, validated and used in detailed parametric studies. • Proposed improved web crippling coefficients for AS/NZS4600/AISI S100 equations. • Developed predictive equations for the buckling loads for DSM based design. • Developed DSM equations for the web crippling design of cold-formed steel sections. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the results of an experimental program investigating blind bolted T-stub connections to unfilled hollow section columns in the tension and compression regions under static loading. The T-stub connection is proposed as an alternative connection to the welded connection currently used as a moment connection for unfilled hollow section columns in the Australian construction industry. The flexural performance of the T-stub connection, in terms of stiffness, has been evaluated in accordance with EC3 classifications and was found to behave as a semi rigid connection under serviceability loading. Results from the experiments have been compared with existing theoretical models that predict the maximum load the flexible column face can carry in the tension region before yielding occurs, and good agreement has been achieved. Furthermore, the experimental results have been used to validate a detailed three dimensional finite element (FE) model which simulates the proposed connection. The developed FE model in turn has been used to perform a sensitivity analysis which is presented in this paper. [Copyright &y& Elsevier]

The reliable assessment of the stability of saturated slopes becomes a challenging task when slopes are consisting of discontinuous materials and containing pre-existing joints. The discontinuous nature of the slopes' material could increase the overall permeability of the slope, while existing joints facilitate groundwater leakage through the joint surfaces into the slope which subsequently exerts a major impact on deformation and the effective stress distribution. This paper aims to study the Pore Water Pressure (PWP) distribution changes in a saturated fractured slope by conducting advanced coupled pore fluid diffusion and stress-strain analyses, while investigating the sensitivity of results to the variation of permeability and leakage properties of fracture surfaces. Modelling of jointed slopes is carried out using the e-Xtended Finite Element Method (XFEM) in conjunction with the Finite Element Method (FEM). In this study, the fluid flow inside the joint is the major focus at which the constitutive response of the fluid inside the joint considers both tangential and normal flows. To demonstrate the state-of-the-art simulation technique presented in this paper, simulation of a fractured slope at the second largest open-pit mine in Australia is performed as a case study. This study shows the effect of a variable leak-off coefficient of the joint surfaces and the permeability magnitude on the pore water pressure distribution. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a fully 3-D numerical investigation into the effect of salinity on ore-forming hydrothermal fluid flow, and develops a highly conceptualized hydrological model to simulate the fluid plumbing system early in the history of the Mount Isa basin, northern Australia when lead–zinc deposits were formed therein. Our numerical modeling results indicate that the active synsedimentary faults and clastic aquifer form a favourable hydro-framework for regional-scale fluid flow, and variations in salinity have important implications for fluid migration and heat transport. When salinity is constant throughout the basin, hydrothermal fluid flow mainly circulates within the more permeable faults as 2-D convection cells, unless the contrast in permeability between the faults and aquifer is less than one order of magnitude. Enhanced salinities on the basin floor due to evaporation of seawater facilitate the development of full 3-D thermohaline flow systems. The 3-D convection rolls established by the evaporitic conditions tend to be stretched if only longitudinal faults exist, but become ‘mushroom-shaped’ when a cross fault is added to intersect the longitudinal ones. The intersection of the two sets of the faults enables seawater to channel downwards to a greater depth and circulate through larger volumes of the source rocks to leach more metal content, and eventually the heated basinal brines ascend to the basin floor via a more ‘localized’ discharge zone at higher venting fluid velocity and temperature, potentially forming giant ore deposits. [Copyright &y& Elsevier]

Aluminium alloys are increasingly popular in structural engineering applications because they have high strength, low weight and great durability. However, the mechanical properties of aluminium alloy material may be significantly affected by high temperature. This paper presents a numerical study on the behaviour of aluminium alloy channel section columns at elevated temperatures. A non-linear finite element (FE) model was developed and validated against 27 experimental results at high temperature. The validated FE model was used to conduct an extensive parametric study, in which a total of 360 aluminium alloy channel section columns were generated at elevated temperatures. The key parameters for the parametric study include two types of aluminium alloys (6061-T6 and 6063-T5), three lengths (360 mm, 1000 mm and 2000 mm) of columns and ten temperatures (range from 24 °C to 600 °C). The design strengths were calculated using American, Australia/New Zealand and European Standards and compared with the numerical results generated from parametric study. In addition, a reliability analysis was used to assess the reliability level of the considered design methods. • Review of test data on aluminium alloy columns at elevated temperatures. • Development and validation of aluminium alloy column models at elevated temperatures. • Parametric studies to generate numerical results on aluminium alloy channel columns at elevated temperatures. • Comparison of test/FE results with existing design methods. • Assessment of existing methods by reliability analysis. [ABSTRACT FROM AUTHOR]

The reliable and optimised design of a drainage system for saturated slopes is often a challenging geotechnical task. Such a task becomes even more challenging when a slope contains pre-existing joints and discontinuities. In saturated and semi-saturated conditions, the existence of joints may lead to a complex distribution of pore water pressure within the slope, affecting the effective stress distribution and the stability of the slope. This paper aims to study the effect of horizontal borehole drainage systems with different arrangements on pore water pressure distributions within a saturated fractured slope. In this study, several coupled pore fluid diffusion and stress-strain analyses were conducted using the e-Xtended Finite Element Method (XFEM) in conjunction with the Finite Element Method (FEM) to simulate the efficiency of a drainage system of a deep slope at the second largest open-cut mine in Australia. As one of the objectives of this study, the effect of water flow inside a joint and normal to the joint surface (normal flow) is considered as an essential simulation component. The results show that the pore water pressure distribution at the vicinity of the joint is considerably influenced by the magnitude of normal flow. Such influence should be taken into account when designing a drainage system, as the magnitude of normal flow and the performance of the drainage system may affect each other directly. [ABSTRACT FROM AUTHOR]

• Radiata Pine manufactured cross laminated timber (CLT) using heterogeneous lamella were investigated. • There was a good agreement in bending results of CLT between the theoretical methods and experimental tests. • Developed FE modelling technique could capture the structural performance of CLT. • Improved bending performance was observed for panels with thinner thickness. Cross laminated timber (CLT) is a sustainable and innovative engineered timber product validated as a viable alternative to more traditional construction materials like reinforced concrete and steel for use in mid-rise prefabricated construction. The structural response of CLT heavily relies on the species of timber used in manufacturing with feedstock varying significantly due to the original source and plantation stand. In Australia, Radiata Pine commonly used for general purpose structural timber mainly in residential house framing. Australia's largest CLT manufacturer, XLam, use Radiata Pine to produce panels for prefabricated construction. The present paper investigates the out-of-plane bending behaviour of 24 XLam CLT panels utilising four-point loading configurations. Experimental results indicated brittle failure modes when the samples were loaded along both the major and minor axes. In addition, plane cross-sections remain plane assumption were confirmed from the strain data obtained from the experimental tests. Various analytical methods (Timoshenko, Gamma (γ), K, and Shear Analogy methods) assessed the bending properties of the test samples, with the shear analogy method yielding the most accurate prediction. Other theoretical methods produced reasonable outcomes in accessing the effective bending stiffness together with bending and shear strengths. Finally, the bending properties of CLT were investigated using finite element analysis, which capture the overall behaviour of Radiata Pine CLT panels adequately. The effect of panel thickness was then examined numerically to observe its effect on bending. [ABSTRACT FROM AUTHOR]

Timber utility poles represent a significant part of Australia's infrastructure for electricity distribution and telecommunication networks. Annual replacement of timber poles are undertaken to avoid pole failures and approximately 40–50 million dollars are spent annually on maintenance and asset management. However, currently practiced inspection techniques for timber poles are mostly subjective in nature and have a lack of reliability, hence, the condition-assessment results provide great difficulties for the asset owners to plan the renewal works. Commonly used wave-propagation based non-destructive testing (NDT) techniques for piles and other concrete structures were adopted and modified to assess the condition of timber poles. The effectiveness of the developed method to detect defects relies on the propagation and reflection of generated shear waves by a transverse impact. However, the orthotropic material properties of timber, the effect of soil embedment, the availability of natural imperfections in timber, and a highly dispersive nature of shear wave propagation make the analysis complex. Therefore, advanced signal-processing techniques are required to identify the damage, the damage location and to accurately assess the damage severity. This paper focuses on damage detection of timber poles using Hilbert-Huang transform as an effective time-frequency analysis technique. A numerical model for an in-situ pole system is developed to simulate the shear wave propagation and to evaluate the capability of the proposed signal-processing technique for an accurate detection of damages. The developed numerical model is validated with the experimental data from the pole yard test and with the data from field-testing. The validated model is then used to simulate different defect profiles, locations and multiple damages to further evaluate the effectiveness of the proposed damage detection technique. [ABSTRACT FROM AUTHOR]