Search

• 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 an experimental investigation of the flexural buckling behaviour and resistance of innovative self-compacting lightweight concrete (LWSCC)-filled cold-formed built-up box section (CFBBS) columns. A series of sixteen LWSCC-filled CFBBS columns and four reference hollow columns formed by two nested asymmetric lipped channel sections using breakstem rivets at flanges with various member relative slendernesses ratios, concrete strengths and section sizes were tested under pin-ended boundary conditions. Material tests and initial global geometry imperfection measurements were carried out and reported in present study. The failure modes and deformation developments, lateral deflection distribution along the column specimens, flexural buckling resistance and load-end shortening relationship of the specimens were scrutinised and discussed concerning the effect of parameters and the associated coupling effects. Furthermore, a comprehensive strain analysis was conducted and reported based on the longitudinal and lateral strain developments at both compression and tension zones under flexure; it was found that the composite action abated as the member length increased. Finally, as there is no existing design codes for LWSCC-filled CFBBS columns, the experimental results were used to evaluate the applicability of relevant international codified provisions, including Eurocode (EC4), Australia/New Zealand Standard (AS/NZS 2327) and America Specification (AISC 360-16). It was found that AS/NZS 2327 yielded the most accurate and moderately scattered predictions while the predictions from EC4 were found to be the most scattered but with reasonable accuracy and those from AISC 360-16 were overly conservative, albeit the least scattered among these design codes. • Pin-ended tests were performed on the LWSCC-filled CFBBS columns. • The flexural buckling behaviour and resistance of LWSCC-filled CFBBS columns were studied. • Influences of concrete strength, member slenderness, section sizes and their coupling effects were discussed. • Comprehensive strain analysis was conducted to scrutinise the composite action. • Existing design provisions were assessed for their applicability to LWSCC-filled CFBBS columns. [ABSTRACT FROM AUTHOR]

• 3D mass timber substructures were tested under an edge column removal scenario. • The applied load was mainly transferred to the three nearest columns. • CLT floors were found to be the critical elements in redistributing the applied load. • Connectors designed with progressive collapse in mind can enhance ductility. • Current industry design method for progressive was found to be conservative. Mid-rise to tall mass timber buildings are becoming internationally popular and are required, for instance in the Eurocode or the Australian building code, to be designed against progressive collapse. Designing against progressive collapse is especially important for mass timber buildings as, when compared to reinforced concrete and steel, timber is a more brittle construction material and mass timber buildings are deemed to be more elastic and have limited rotational capacities at the beam-to-column connections. However, whilst the ability of reinforced concrete and steel buildings to resist such an extreme event has been widely researched, limited studies were carried out on mass timber buildings. Their load transfer mechanisms and structural response after the loss of a load-bearing element are currently unclear. Consequently, this paper presents the outcomes of three experimental tests performed on three scaled-down, 2 × 2-bay, post-and-beam mass timber substructures under an edge column removal scenario. The capacity of the 3D substructures to resist progressive collapse was investigated for two types of beam-to-column connectors, namely two tests performed with a connector type commonly used in Australia in mass timber buildings and one test with a proposed novel connector. In the tests, Uniformly Distributed Pressures (UDP) were applied to the floors in two stages: (i) a constant UDP of 4.8 kPa was first applied to the bays not adjacent to the removed column and (ii) an idealised UDP was then increasingly applied to the remaining two bays through a hydraulic jack connected to a six-point loading tree. The load redistribution mechanisms or alternative load paths, structural response and failure modes were recorded and are presented in this paper. Results showed that the applied load was principally transferred to the three columns closest to the removed column and that the Cross Laminated Timber (CLT) panels spanning over two bays were efficient in resisting and transferring the load. The substructure with the proposed novel connector showed an 8.5% increase in capacity and higher ductility than the substructures assembled with the commonly used connector. A simplified theoretical model consistent with the methodology currently used by industry to predict the collapse resistance capacity of post-and-beam mass timber buildings was compared to the test results. The model underpredicted the test capacity by 53%. [ABSTRACT FROM AUTHOR]

• Australian water pipes failure lifetime data are studied by probabilistic methods. • A simple stress concentrated model is used to describe the cast iron pipe failure subjected to corrosion. • The proposed model captures some essential features that can be used for remaining life prediction of corroded pipelines. At present, a significant proportion of Australia's ageing water infrastructure is composed of cast-iron pipes. The corrosion of cast-iron pipes is the main triggering factor for Australia's water industry. It has been found that the failure mode of small diameter water mains (<300 mm external diameters) from Yarra Valley Water is mainly the longitudinal failure (hoop-stressed) instead of broken back failure, which is unexpected. Therefore, the purpose of this paper is to examine the failure mechanism of longitudinal failure of small diameter cast-iron pipes. The observational failure database provided by Yarra Valley Water show limited data availability. This has stimulated the focus of this paper: to examine the corrosion mechanism by utilising probabilistic inverse analysis for unknown physical parameters. Focusing on the likelihood of failure, this paper investigates the performance of small diameter cast-iron pipes by using statistical analysis based on the observational failure lifetime data within pipe cohorts. Background studies on the deterioration of cast-iron pipes due to corrosion are made to help set up the probabilistic physical modelling (PPM). Using the updated corrosion parameters, the lifetime probabilities of failure and the hazard rate of the cast iron model are derived from PPM. Last, it is found that the modelling results agree reasonably well with prediction curves of statistical data, indicating that the proposed method for pipe lifetime prediction is promising. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) Tab connections are popular due to their rapid fastening and ease of installation, and their applications have increased recently in Pacific countries, including Australia and New Zealand. This type of connection consists of a Tab plate formed from the web of the supporting beam and is screwed to the joist web, providing a dependable load path from the joist to the galvanized C-section supporting beam. However, no studies have been reported in the literature for the shear capacity of such connections. This paper presents a shear test program designed to determine the shear capacity of CFS Tab connections and to identify their failure mechanism. The experimental program included three different beam sizes, C-150, C-190 and C-240. Each test was repeated three times, resulting in nine tests in total. All the specimens failed in plate yielding and plate tearing, which occurred on the tension side of the plate (top region). Nonlinear finite element (FE) models were then developed and verified against the test results. The FE results showed good agreement with the test results in terms of connection stiffness, connection strength and failure modes. Finally, it was shown that the design equations given in the Australia/New Zealand standard (AS/NZS 4600) and American Iron and Steel Institute (AISI S100) for predicting the combined bending and shear capacity could predict the ultimate shear capacity of CFS Tab connections investigated in this study. • The results of monotonic shear tests of a novel CFS Tab connection are reported. • CFS Tab connections failed in plate yeailding and tearing. • A nonlinear FE model is developed. Results showed good agreement with the test results. • A design procedure is proposed for predicting the shear capacity of CFS Tab connections. [ABSTRACT FROM AUTHOR]

• Flat-ended circular hollow sections were tested in tension. • Three bolt configurations were established in flattened ends. • Bearing failure and net-section fracture were observed. • The test load increased with increase in the number of bolts. • An adjusted bearing coefficient is suggested for bearing. Experiments were performed to investigate the behaviour of 28 circular hollow sections (CHSs) in tension, with flat ends and three bolt configurations (2, 3 and 4 bolts). The length of the members between the flat ends was kept constant at 1500 mm for all CHSs, and the sizes of the sections ranged from 60.3x2.0 to 101.6x4.5. Two modes of failure were observed, viz; bearing failure (BF) and net-section fracture (NSF). CHSs connected with 2 bolts failed in bearing, whilst net-section fracture was dominant in sections with 3 and 4 bolts. The notion that the change in the number of bolts can lead to different behaviours of the connections is a significant contribution to knowledge, particularly if flat-ended CHSs are used as structural truss elements. This paper demonstrates that the sections are capable of supporting large loads, however, the capacity of the tested specimen did not reach the full yield strength. It is apparent from the tensile strengths that a larger increase in strength was accomplished when the number of bolts was increased from 2 to 3 bolts than from 3 to 4 bolts. A comparison of the tensile strength with the strengths predicted by the North American standard (AISI S100-16w/S1-18), Australia/New Zealand standard (AS/NZS-4600:2018) and European standard (EN 1993–1-3) confirm that both standards provides a reasonable assessment of the strength of the 3 and 4 bolt configuration, which failed purely by net-section fracture. However, for the 2-bolted connections, which failed in bearing, it is proposed to use AS/NZS 4600:2018, with a bearing coefficient of C = 2.85, instead of C = 3.0, to increase the accuracy of the bearing strength expression for these specimens. [ABSTRACT FROM AUTHOR]

In this paper, the structural stability and compressive capacity of pin-ended cold-formed stainless steel angle columns with different slenderness were experimentally investigated. The experimental programme was performed on press-braked lean duplex stainless steel equal-leg angle sections with nominal dimensions of 80 × 80 × 4 mm, and involved material testing, initial imperfection measurements and 11 column tests. The test setup and procedure, together with the key experimental results, axial load vs. lateral deflections, axial load vs. torsional rotations and characterised failure modes, were fully reported and analysed. The experimental observations reveal that the failure mode type, including local/torsional, flexural-torsional and flexural effects, is highly dependent on the column's slenderness and initial imperfections. The measured compressive strengths were compared with the resistance predictions determined according to European and Australia/New Zealand codified design procedures. It was found that experimentally obtained ultimate capacities are significantly higher than those calculated according to the specifications. However, the database of test results is still quite limited, and a further research is needed to amplify the data needed to enable a more precise assessment of the codified procedures. • Eleven pin-ended cold-formed stainless steel equal-leg angle columns were tested. • Different buckling failure modes were systematically investigated. • Failure loads conservatively predicted by European and Australian design procedures. [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]