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Reinforced concrete (RC) walls subject to in-plane lateral loads are essentially subject to axial compression and tension forces in the respective end regions of the wall. The tension forces initially result in elastic tensile stresses in both the concrete and longitudinal reinforcement. Cracking occurs after the maximum tensile stress of the concrete has been exceeded and results in the reinforcement providing the sole tensile resistance at each crack location. The mechanical interlock between the reinforcement and concrete means that a portion of the tensile stress in the reinforcement at each crack is transferred back into the concrete between adjacent cracks. This mechanism stiffens the concrete in tension and is referred to as tension stiffening. This paper presents a generalised tension stiffening model developed for limited ductile (i.e. lightly confined) RC walls. However, it is also applicable for lightly confined RC elements generally. The model was validated against 14 boundary element prism specimens subject to cyclic loading, with very good correlation observed between the theoretical model and the experimental results. This model can easily be adopted into a sectional analysis procedure to account for tension stiffening in both the elastic and inelastic regions of response in an RC wall.

To produce plastic parts of high geometrical quality and dimensional stability through injection moulding process there are several key variables that must be considered. These include processing parameters such as packing time, cooling time, packing pressure, melt temperature, mould temperature and the intrinsic melt flow characteristics of polymeric materials used to produce the part. The challenge of producing high quality part is further compounded if the input polymer material is of reclaimed waste streams with inherent inconsistency in their nature. In this work, significant number of simulation-based studies are conducted using Autodesk Moldflow software to delineate the contributing issues pertinent to the part quality and achieve topological optimization by reducing critical parameters of shrinkage and warpage while ensuring overall cycle time viable for industrial production rates. Key simulation variables were obtained through experimental characterization of flow and thermal properties of the recycled olefin plastics. Different gate locations were simulated, and the best gate locations were selected for a two-gate system. These gates were provided with gate valve controllers for controlling the polymer flow to create cascaded injection moulding scenarios. Such scenarios were iterated with the objective of reducing the pressure required for cavity filling and thereby reducing the clamp force required. Optimized melt and mold temperatures of 245 °C, 20 °C were used for all the simulations performed. The result obtained from the most optimized simulation showed an average cycle time of 10.42 secs, volumetric shrinkage of 5.08%, warpage of 1.05 mm and clamp force of 79.81 tonne would be required to produce a part of 200 mm*100 mm*1.5 mm dimensions. Following a cascaded injection setup, it was shown that the clamp force could be reduced by 60.57%.

This article investigates the development of the following material properties of concrete with time: compressive strength, tensile strength, modulus of elasticity, and fracture energy. These properties were determined at seven different hydration ages (18 h, 30 h, 48 h, 72 h, 7 days, 14 days, 28 days) for four pure cement concrete mixes totaling 336 specimens tested throughout the study. Experimental data obtained were used to assess the relationship of the above properties with the concrete compressive strength and how these relationships are affected with age. Further, this study investigates prediction models available in literature and recommendations are made for models that are found suitable for application to early age concrete. Results obtained indicate that the relationship between the splitting tensile strength and concrete compressive strength can be approximated with a power function between 0.7 and 0.8, and this correlation is not affected by age. Fracture energy of the concrete and modulus of elasticity values obtained in this study correlate well with the square root of the compressive strength and it was found that this relationship holds true for all hydration ages investigated in this paper. Inverse analysis on the wedge-splitting test was conducted to determine the direct tensile strength. Values of tensile strength obtained from the inverse analysis have been validated numerically by carrying out finite element analysis on the wedge split, and anchor pull-out tests. The ratio of the tensile strength obtained from the inverse analysis to the splitting tensile strength was found to be in the range of 0.5&ndash, 0.9 and 0.7 on average.

Precast concrete building cores are a widely used lateral load resisting system in low and mid-rise multi-storey buildings. However, despite their widespread use in countries like Australia or New Zealand, a very little research or experimental testing has been undertaken to assess their lateral drift behaviour. This article will present the findings and observations of a recent experimental testing programme into reinforced concrete precast building cores, which included three large-scale ‘box-shaped’ precast building core specimens. Adjacent panels in each specimen were connected together using welded stitch plate connections and then connected to foundation blocks on the top and bottom using grout tube connections. The results of the testing showed that the welded stitch plate connections were too flexible to allow full composite action to be developed in the cross-section, which meant the precast building core specimens were around 25% more flexible than an equivalent cast in-situ version. The testing also highlighted common detailing and construction deficiencies that can severely inhibit the ductility of the core.

Timber utility poles are significantly used in power and telecommunication infrastructures all over the world. The deterioration of timber with time is common due to various factors including termi...

Timber utility poles represent a significant part of the power distribution and telecommunication infrastructure. Weathering, decay induced by fungus, and termite attacks deteriorate the condition of timber poles, causing a loss in their strength and toughness. Routine inspections are carried out to assess the condition of poles using conventional inspection techniques. However, the reliability of these techniques is in question. This paper proposes the stress wave propagation (SWP) technique for condition assessment of timber poles and the direct application of the artificial neural network (ANN) pattern recognition algorithm for signal classification. A Fourier-based signal decomposition method has been adopted and the frequency domain statistical features of the decomposed subcomponents were extracted to be used as the inputs for the ANN. Experiments were conducted using both intact and defective timber poles subjected to stress wave propagation. Different ANN models have been developed to classify the signals, and several controlling parameters were evaluated to obtain the best performance model. Further, the support vector machine (SVM) and k-means clustering algorithms were employed to classify the stress wave signals from intact and defective poles. Finally, the results of developed ANN models, SVM classifiers and k-means clustering models for pole classification were compared. The obtained success rates of the ANN model, the SVM classifier and the k-means clustering algorithm were 92%, 87% and 81%, respectively. Further, the trained ANN model was used to predict the health status of in-service poles, which were uprooted and subjected to full-scale bending tests after performing the stress wave propagation.

Screw anchors are widely used in applications such as fastening base plates in steel and metal construction, formwork and bracing, structural steel applications, railings and handrails. At present, researchers and design engineers rely on the Concrete Capacity Design (CCD) method to predict the strength of screw anchors under the tensile loading as the only method available in literature. In CCD method, the underlying assumption is that the concrete cone and combined concrete cone and pull-out failure modes are the main failure mode for anchors, whereas, previous studies have demonstrated that pull-out is also a very common failure mode of screw anchors. In this paper, experimental results of more than 180 tests on one particular type of screw anchors are studied to better understand their behaviour under tensile loading. Experimental results are classified based on the observed failure modes. New equations are proposed to predict the tensile capacity of this particular type of screw anchors associated with each of the above mentioned dominant failure modes for the first time. The experimental results are compared with the predicted values by the CCD method and specifications provided by the anchor manufacturer. It is also shown that in majority of cases, the CCD method overestimates both the experimental results and the specifications given by the manufacturer.

Behaviour of low rise cold-formed steel-framed residential structures when subject to lateral loading (e.g. wind and earthquake loads) is significantly influenced by both structural and non-structural elements. The ceiling is normally considered as a horizontal diaphragm for the distribution of such lateral loads to the bracing walls. In Australia, the ceiling diaphragm, in single and two storey cold-formed steel-framed houses, is made of plasterboard lining fixed to ceiling battens which in turn are screwed to the roof trusses. Determination of the stiffness and strength of the ceiling diaphragm is crucial for accurate distribution of the lateral load to the lateral resisting elements (e.g. bracing walls). This paper presents experimental results from tests of typical ceiling diaphragms. Further, a detailed finite element model is described which was validated against the experimental results. The model is capable of reproducing the initial stiffness, non-linear deformation and ultimate strength. The finding from this work would assist engineers in designing the lateral load resisting system for houses.

The application of hysteretic damper has gained major attention in seismic resistant design of buildings. It provides an efficient and cost-effective solution to reduce the level of damage induced on the building due to seismic excitations. The efficiency of the damper is influenced by parameters such as yield strength, yield displacement and brace-damper assembly system stiffness. The premise of this paper is to investigate the effect of the uncertainty associated with the hysteretic damper design parameters on the probabilistic seismic performance of steel buildings. Two steel buildings which are designed in accordance with the European Standard design code are evaluated. The uncertainties associated with the damper design parameters are incorporated using the Optimised Latin Hypercube sampling method for different confidence levels. The building response is obtained by conducting nonlinear time history analyses in OpenSEES. The annual frequency of exceeding a damage limit state, which is quantified by integrating the seismic fragility curves and hazard curves, is computed for the steel buildings with and without consideration of the design parameter uncertainties.

The project ‘Cost-Effective Mitigation Strategy Development for Building Related Earthquake Risk’ under the Bushfire and Natural Hazards Cooperative Research Centre (BNHCRC) aims to develop knowled...

This paper presents the tensile behaviour of individual Double Headed Anchored Blind Bolts (DHABBs) which are anchored within Concrete Filled Square Hollow Section (CFSHS) tubes. The DHABB consists of a conventional Headed Anchored Blind Bolt (HABB) with one additional middle head, between the existing end head in the embedded region and head next to the tube wall. A series of experiments were conducted on the pull-out of single DHABBs under monotonic and cyclic loading using different tube sizes, bolt sizes and concrete types. Detailed results from the experimental work are presented in this paper. A comprehensive three dimensional finite element model was developed and the results were compared with full scale pull-out test results. A good agreement was obtained between the FE and experimental results.

In this paper, the cyclic behavior of groups of double-headed anchored blind bolts (DHABBs), which are anchored within concrete-filled square hollow sections (CFSHSs), is investigated. The ...

Timber utility poles are extensively used in power distribution and telecommunication sectors to support the overhead cables and other attachments. These utility poles are designed to have sufficient inherent capacity to withstand the imposed actions. However, timber poles deteriorate with time losing the strength and toughness mainly due to weathering, decay and termite attacks. Therefore, pole failures occur when the imposed stresses on the pole exceed the remaining strength of the pole. It is essential to avoid pole failures which will have severe safety concerns and significant economic impacts. This paper presents a brief review of the currently available timber deterioration models and proposes a framework for evaluating the residual strength of the in-service timber utility poles. The developed framework permits the asset managers to evaluate the structural reliability of these assets and to determine the optimum pole replacement rates. The residual strength of an in-service pole is directly related to the remaining section modulus of the pole at its critical section which is the ground line region of the pole. Hence, this paper presents the evaluation of the remaining section modulus for sectioned pole specimens which were condemned from service due to pole replacements. Further, the variation of section modulus with the service life is illustrated for the analysed Australian pole specimens and compared with the predictions of the current deterioration models.

Modular buildings are built using factory manufactured building units or modules that are transported and assembled on-site. Among the many different types used, modules of volumetric form analogous to intermodal freight containers have the greatest potential to achieve complete building systems or fully-modular building systems where on-site work could be reduced to foundation, module assembly and the finishing of module-to-module interfaces as required. However, despite the many reported benefits, volumetric module use has some technical, logistical and regulatory issues that have constrained its widespread application. Two of such issues that have been widely reported are the lack of efficient structural systems for lateral load transfer and the lack of high-performance inter-module connections that can not only meet structural demands but can also fulfil certain constructional and manufacturing needs as well. Therefore, this paper focuses specifically on the latter of the two identified issues and briefly summarises the work conducted into its resolution.

The work of breathing through north- and south-facing Portex Polar 'Blue-Line' paediatric tracheal tubes of sizes 3.0-7.0 mm ID has been measured using sinusoidal flow at equivalent ventilatory rates of 10-50 breaths min-1 with tidal volumes of 10-500 ml. North-facing tubes are designed to sit with the connection on the forehead after intubation, whilst south-facing ones are designed so that the connection sits on the chin of the patient. It was found that the total work of breathing through north-facing tubes is approximately 8% higher than the total work of breathing through south-facing tubes of the same size, irrespective of tidal volume or respiration rate. The total work of breathing was dependent on total tube length but independent of tube design. The endotracheal connectors themselves were found to contribute a significant proportion of the total work of breathing but there was no significant difference between the inspiratory and expiratory performance of the tubes.

Reinforced concrete (RC) impact-resistance barriers, such as rockfall barriers, often consist of a cantilever RC wall, which is expected to experience flexural bending under impact loading ...

The Christchurch earthquake has given a renewed impetus to the development and use of low damage connections within moment-resisting frames in New Zealand. When using a low-damage technology, the building is designed to be easily repairable after a severe earthquake and is hence expected to be more resilient and cost-effective. This paper reports on a sub-assemblage test that investigates the behaviour of a newly proposed low damage connection between a steel beam and composite column. The connection incorporates blind-bolts, curved T-stubs and replaceable buckling restrained fuses (RBRFs). The RBRF is the only element which is allowed to yield when the earthquake level is higher than the design-based earthquake, so the establishment of a suitable strength hierarchy is vital to the success of the design. Two loading protocols have been applied using the same sub-assemblage but with a new RBRF at the start of each test; i.e. the RBRF was replaced after each test. The contributions of the connection, beam, and column to the total rotation have been summarised. The results show that a semi-rigid connection can be achieved by using this type of connection. Furthermore, an analytical approach has been proposed to predict the behaviour of this type of connection.

Exterior beam-column joint is typically the weakest link in a limited-ductile RC frame structure. The use of diagonal haunch element has been considered as a desirable seismic retrofit option for reducing the seismic demand at the joint. Previous research globally has focused on implementing double haunches, whilst the performance of using single haunch element as a less-invasive and more architecturally favourable retrofit option has not been investigated. In this study, the feasibility of using a single haunch system for retrofitting RC exterior beam-column joint is explored. This paper presents the derivation of the key formulations for the implementation of a single diagonal haunch as well as the generalization of the formulations for all three systems: the non-retrofitted subassembly, the double haunch retrofitting system, and the single haunch retrofitting system. The formulations have then been validated by available experimental data for non-retrofitted subassembly and double haunch retrofitting system. Finally, the effectiveness of the single haunch retrofitting system is compared with that of the double haunch retrofitting system through a parametric study.

Impact of hailstone and flying debris in extreme weather conditions is a major contributor to damage to glazing panels and other types of building facades. Localized damage to the glazing panel in the form of Hertzian fracture is controlled mainly by the amount of force that is developed at the point of contact. Weibull statistics forms the foundation of contemporary probabilistic models designed to estimate the value of the limiting force to result in Hertzian fracture. This conventional approach to probabilistic modelling has significant shortcomings as the calibrated probabilistic parameters have to be specific to the type of installations. The alternative approach of predicting risks of Hertzian fracture is by stochastic simulations of Griffith flaws. This paper presents an adaptive stochastic simulation methodology for predicting risks of Hertzian fracture of glass which is subject to the impact by hail and flying debris. The proposed simulation model has been verified experimentally for annealed glass based on comparison of the simulated contact force values against results from experimental measurements. The introduced simulation procedure has been used for assessing the risk of Hertzian fracture in both annealed and toughened glass. The use of the adaptive stochastic modelling methodology for predicting Hertzian failure in scenarios of hail impact is illustrated in this paper by examples.

Modular building construction is an emerging trend in the construction industry. During the course of road transportation of the modular unit of a building, vehicular vibrations on the truck-trailer may cause damage to components that are attached to the unit. The amount of dynamic loading depends on many parameters including the level of loading on the vehicle, location of the centre of mass, suspension setup of the truck-trailer, and amount of damping of the vibrating parts. The effects of these parameters on the vertical motion of the trailer-chassis are the focus of interest in this study. The acceleration response spectrum representing the filtering effects of the suspension system and that of the mounting can be calculated by modelling road roughness as a stationary Gaussian process , whereas the truck-trailer-trailer is represented as a 2D pitch-plane model. Parametric variations in the acceleration response spectra are presented in the compact form of peak value curves. An algebraic expression for calculation of the maximum spectral accelerations experienced by attachments to the unit is also presented. It is concluded at the end of the study that a component mounting should be designed to withstand a vertical acceleration of the component of up to 32 m/s. 2 (or 3.3 g) in both directions in addition to gravitational acceleration . The design of mountings and their connections which satisfy this strength requirement can be deemed sufficiently robust to withstand vibration in the normal course of road transportation without the need for any further assessment. Less conservative predictions of the strength demand can be obtained using recommended algebraic expression or design charts provided in the paper.

Modular building construction relies on prefabricated modules which are assembled onsite to form complete buildings. The assembly requires modules to be connected at discrete locations and results in the formation of discontinuous diaphragms. Diaphragm discontinuities could potentially lead to structural instability or possible diaphragm failure if unaccounted for. Therefore, the primary objective of this study is to evaluate the influence of in-plane diaphragm stiffness and strength on the seismic performance of multi-story modular buildings. A simplified method is presented to establish diaphragm service stiffness considering shear deformation of individual module diaphragms as well as shear and axial deformation of diaphragm connections. This method is used to construct numerical models of a four-by-four bay four-story modular steel building. Three diaphragm stiffness levels, namely rigid, stiff and flexible, are considered for these models and were each subjected to 44 horizontal ground motions relating to seismic events having a return period of 500 years. The results show that increased diaphragm flexibility leads to inter-story drifts that are dramatically large and inertial forces that are considerably different from calculated values using the equivalent lateral force procedure described in current seismic codes. This study is extended further to evaluate performance targets for both elastic and inelastic diaphragm response under a seismic event having a return period of 2500 years. The results are used to propose new seismic design factors, which include force and ductility amplification, and could be implemented for the design of diaphragm connections in multi-story modular buildings.

Cast-in fastenings for use in concrete are widely used in Australia. While design guidelines for headed fasteners are currently in place in Europe and the US, guidance on the design of hold-down bo...

Low-damage technologies have been developed in recent years which limit the damage imposed on structural elements when a building is subjected to a very rare earthquake event. This has been achieved by a capacity design approach applied to the connections in which the ductile part of the connections yields and all other structural elements remain elastic. Examples of low-damage connections are the sliding hinge joint in steel buildings and variations associated with this, and a combination of a post-tensioning system and mild steel dissipater in precast concrete and timber buildings. A system developed by the authors uses replaceable buckling restrained fuses (RBRFs) that do not require a post-tensioning system to be used conjointly. This system has been studied both experimentally and numerically. This paper considers the use of RBRFs as an energy dissipation device installed at beam-column connections in composite moment-resistant frames. These RBRFs could be replaced after a major event, and hence would cause little disruption. A 2D building frame has been modelled for a case study and its behaviour under 100-year, 500-year and 2500-year return period earthquake events has been summarised. A consecutive earthquake with a return period of 500 years or 2500 years has been applied to the building following both 500-year and 2500-year return period earthquake events. This study was performed since there is a possibility that the consecutive earthquake would occur prior to the replacement of the RBRFs. The results show that the building could still sustain the consecutive earthquakes with little additional residual displacement.

Concrete Filled Steel Tubes (CFSTs) are being used as columns in moment resisting frames in many parts of the world. Because of their aesthetic appearance, favourable ductility and large load bearing capacity, they are popular with architects and engineers. The use of CFSTs is limited in some countries (like Australia) due to the problems and cost associated with the connection of steel beams to the closed column section, unlike open H-shaped columns where ordinary structural bolts can be used. In this paper, a structural system is proposed which uses moment resisting frames as the lateral load resisting system. This system eliminates the use of welds at the site, which is the most common method, although expensive, which is used to achieve a moment resisting connections. The proposed system uses double T-stub connections to connect universal beams on opposite sides of the CFST column, and headed anchored blind bolts are used to connect those T-stubs to the column. This system provides sufficient stiffness and strength to be used in low to mid-rise buildings in low to moderate seismic regions. The proposed system uses a capacity design method to limit the load and non-recoverable damage in the connection (especially in the anchorage). One of the components in the connection, the web of the bottom T-stub, is designed as a fuse to create a low damage system for very rare earthquakes.

Condition monitoring of mining conveyor is a highly essential task to ensure minimum disruption to the mining operational system. Failure of one or more conveyor components can result in significant operational downtime, economic loss, and safety risks. The current monitoring method still involves subjective measure from maintenance engineers, where at some cases, fault can be left undetected and leads into site incident. Therefore, there is a high demand for real-time condition monitoring technology to detect early fault on conveyor. In this study, the effective application of distributed optical fibre sensor (DOFS) was explored for long distance real-time condition monitoring of mining conveyor. The fault detection framework was developed by integrating and modifying the Isolation Forest algorithm to analyse optical signals for effective detection of defective idlers. Further, the optical signal was analysed to extract the damage progression of defective idler with time and space. The results were used to classify various levels of damage and to set appropriate damage thresholds. Also, software interface, that can be used to set the sensing parameters, to collect, analyse, and visualise the signal in real-time, was developed. Finally, the developed condition monitoring system was used to monitor a 1.6 km long section of a conveyor structure in Western Australia for a period of 10 months. The results and findings from the field monitoring were presented together with automated fault detection framework for condition monitoring of mining conveyor.

In regions of low-to-moderate seismicity, the design of multi-story buildings with strong-beams weak-columns are quite common, which triggers the formation of a soft-story collapse mechanism during rare ground motions. A design approach to overcome this issue is introducing a ductile soft-story at the first level, such that the damage is controlled, while the above stories remain in the elastic response range. In this approach, the ductile soft-story acts as an isolator and limits the damage at only the first-level, thereby reducing the cost and time of repair and improving the safety and resilience of these buildings. The use of concrete-filled steel tube (CFT) columns can be considered as an attractive solution to construct such ductile soft-stories. To validate this concept, the multi-axis substructure testing (MAST) system at Swinburne University of Technology is used to conduct a set of 3D quasi-static cyclic tests on CFT columns with both circular (CCFT) and square (SCFT) cross-section shapes. A combination of bidirectional horizontal load protocol with vertical load variation is applied to the specimens. The data obtained from these experiments are used to study the physical damage progression and hysteresis response of CCFT and SCFT columns under complex 6-DOF boundary forces. The obtained experimental data are then used to calibrate FE numerical models to conduct performance-based fragility analysis of the soft-story buildings, at the system level, and vulnerability assessment of CFT columns, at the component level. The results show confidence in the superior seismic performance of CFT columns and highlight the advantages of using these elements in the construction of seismic resilience and sustainable buildings.

This paper provides an overview and the results of a recent experimental study testing the lateral cyclic displacement capacity of limited ductile reinforced concrete (RC) walls. The experimental program included one monolithic cast in-situ rectangular wall specimen and one monolithic cast in-situ box-shaped building core specimen. The specimens were tested using the MAST system at Swinburne University of Technology. They were tested under cyclic in-plane unidirectional lateral load with a shear-span ratio of 6.5. The specimens were detailed to best match typical RC construction practices in regions of lower seismicity, e.g. Australia, which generally results in a ‘limited ductile’ classification to the Australian earthquake loading code. This reinforcement detailing consisted of constant-spaced horizontal and vertical bars on each face of the wall and lap splices of the vertical reinforcement at the base of the wall in the plastic hinge region. The rectangular wall and building core specimens both achieved a relatively good lateral displacement capacity given the limited ductile reinforcement detailing adopted. The lap splice at the base of the specimens resulted in a somewhat different post-yield curvature distribution being developed. Rather than a typical plastic hinge with distributed cracks being developed, a ‘two crack’ plastic hinge was formed. This consisted of one major crack at the base of the wall and another at the top of the lap splice, with only hairline cracks developing between these two major cracks. The majority of the plastic rotation was concentrated in each of these two major cracks.

Ground-borne vibrations induced by mine blasting are typically of low amplitudes, which are not considered a major concern for modern engineered structures. However, historic structures are often c...

This paper presents a simplified approach to estimate the pull-out behaviour of headed anchor blind bolts (HABB) from concrete filled circular hollow section (CFCHS). The approach was developed based on a multi-linear component spring model representing the behaviour of the blind bolt’s components, i.e. the bolt’s shank, the embedded head, and the washer bearing on the inside of the tube wall. Extensive finite element analyses (FEA) were used to develop and calibrate the nonlinear behaviour of each component for monotonic loading only, in which the yield and ultimate strength, as well as the initial and secant stiffness of each component were taken into account. Important parameters such as the diameter of the HABB, diameter and thickness of the circular hollow section (CHS), embedment depth of the embedded head, and concrete strength are also incorporated in defining the component spring behaviour. The proposed method was able to yield a good match with both the FEA and test results for the individual component behaviour in terms of the initial and secant stiffness as well as the ultimate strength. Moreover, the load transfer and failure sequences of the HABB within a CFCHS are discussed, and the assembly procedures of the component springs are proposed, by which the combined component behaviour is identified and matches well with both the FEA and test results.

behaviorA detailed parametric study was conducted to determine the influence of the key parameters affecting the cyclic axial of replaceable buckling restrained fuses (RBRFs). These RBRFs a...

The impact by debris can result in extensive damage to building facades and roof coverings in extreme climate conditions such as windstorms and hailstorms. Damage can be in the form of denting on the surface of a metal cladding panel, which is controlled by the amount of force developed at the point of contact between the debris object and the surface of the panel. Amid the lack of guidelines for assessing damage to the building envelope, it is common to conduct impact tests on a cladding specimen. Such tests often involve the use of a gas gun to fire projectiles; however, there are shortcomings with this approach as it is mostly undertaken to check compliance and to observe permanent damage to the specimen. This paper presents the use of quasi-static tests to simulate the impact induced damage to metal cladding in storm scenarios. The contact force value generated during the impact action is predicted using the two-degree-of-freedom system model so that the impact action can be applied in a quasi-static manner on an MTS machine to predict damage in the form of indentation or perforation. This experimental technique for predicting damage is illustrated and verified in this paper by conducting confirmatory impact experiments. The risk of damage to metal cladding caused by impact in storm scenarios could then be assessed with confidence without having to conduct repetitive impact testing involving accelerating projectiles onto specimens of metal cladding. This research provides designers with an accurate and cost effective means of quantifying impact induced damage on building facades, and allows system developers to adapt and utilise existing and new materials to develop innovative solutions for withstanding impact.

Past studies have confirmed that the behaviour of an infill-frame can be remarkably different from that of a bare frame. This becomes specifically critical when the structure is under lateral loads such as wind and earthquake. This paper looks into the fundamentals of the most commonly used analytical method for the analysis of such structures, i.e. equivalent strut modelling. It is shown that even though several equivalent strut models have been proposed since the 1950s, none can be considered as a suitable generic tool to represent the behaviour of all infill-frame structures. It is further demonstrated that not only the total width of strut(s), but also the number and location of strut(s) may vary from one infill-frame to the next. It is also shown that even for the same infill-frame the strut properties change at different drift values. A methodology is proposed to develop an appropriate strut model incorporating the material nonlinearities for any given infill-frame. This methodology requires the analytical results of a primary FE model at a micro level to determine the geometric properties of struts.

Impact by flying debris in windstorms conditions has been a major contributor to damage to aluminium and other types of building facades. The damage so caused to cladding panels was mainly controlled by the amount of force that was developed at the point of contact between the debris object and the surface of the target. However, no codified design guidelines are currently available to quantify the required impact resistance of an aluminium panel for given storm scenarios. Current analytical expressions derived for analysing impact actions as reported in the literature are mostly based on the use of energy principles. The influence of the hardness of the debris object and the magnitude of the contact force has not been taken into considerations. Thus, the amount of deformation that is inflicted on the panel by the impact of a non-rigid projectile object can be over-stated. This paper presents an analytical expression that has been developed for estimating the severity of damage to the surface of a cladding panel (and to determine if leakage of rainwater from the panel can be resulted) for given mass of the debris object, velocity of impact, and importantly, parameters characterising the stiffness properties of the impactor object.

This paper presents an overview and results of a recent experimental testing program of nonductile reinforced concrete (RC) wall boundary elements. The experimental program consisted of 17 boundary element prism specimens that are meant to represent the end regions of nonductile RC walls. The failure mechanisms of interest were global out‐of‐plane buckling and local bar buckling of the vertical reinforcement. The matrix of test specimens included: high and low slenderness ratios (that is, height-to-thickness ratio); cast-in‐place and precast wall construction methods; and specimens that were detailed with either a single central layer of vertical reinforcement or two layers of vertical reinforcement, one per face. Strain-rate affects were also assessed in the experimental program. The paper concludes with a detailed discussion of the test results, comparisons with similar experimental programs and design models in literature, and guidance on tensile strain limits for the displacement-based design of nonductile RC walls.

Timber poles are extensively used in power and telecommunication networks all around the world. Timber utility poles have high initial strength, but susceptive to fungus and termite attacks which results in deterioration with time. It is difficult to observe the defects by looking from outside and in most of the cases, defects are observed below the ground. Power distribution and telecommunication companies conduct routine inspections on utility poles to assess the structural integrity and to avoid failure of poles which will have serious safety concerns. But most of the present pole inspection techniques are subjective methods and highly qualified personnel are required for inspection. In comparison, non-destructive testing (NDT) methods can be effectively used to assess the condition of timber utility poles. This paper provides a brief review on in-service assessment methods and focuses on stress wave propagation technique as a non-destructive test for the condition assessment of timber utility poles. Theory behind stress wave propagation technique is the observation of reflection patterns of stress waves generated by an impact load on timber pole. Longitudinal waves or transverse (shear) waves may be generated depending on the direction and location of the impact. Resulting signals due to the response of the pole are processed in time and frequency domains to obtain important information about the condition of the utility pole. Wavelet transformation is used as an effective tool for processing the signals obtained from numerical models and practicality of the mentioned method is verified using the signals obtained from field testing.

A large scale instrumented impact experiment was conducted on a fixed base reinforced concrete wall in view of the lack of such experiment in the literature. A 1.5 m tall, 3 m wide and 0.23 m thick reinforced concrete wall fully fixed to the ground was used as the specimen. Two steel impactors with mass of 280 and 435 kg were released from controlled heights ranging from 0.2 to 1.4 m to strike the top of the wall. The experiment was carried out in a fully controlled laboratory environment with the impact conditions and structural behavior of the specimen recorded. Over 60 pieces of instruments were employed to achieve that. In this paper, the details of the test setup, specimen, impactors and instrumentation will be presented, alongside with some of the recorded results. A key observation from the results is that the structural response of the target wall can vary significantly when the impact energy was kept the same across different impactor mass. It was also found that the maximum contact force applied to the structure is not representative of the structure’s actual impact response.

An experimental investigation involving the use of a full-scale pendulum device to deliver solid object impact on a reinforced concrete (RC) barrier specimen that was fitted with a layer of gabion cushion is reported in this paper. The deflection behaviour of the stem wall of the RC barrier including the tensile strains developed in the longitudinal reinforcement was of interests. Results recorded from the tests are compared with results from control experiments which were without the protection of any cushion materials. The introduction of a layer of cushion is shown to be able to have the contact force reduced by more than 95% and deflection demand reduced by about 70%. An analytical procedure employing the Hunt and Crossley contact model, Swiss code model and two-degrees-of-freedom (2DOF) system modelling technique is presented for calculating the flexural response behaviour of the cushioned barrier and validated by comparison with experimental measurements. An important outcome from the study is a simple hand calculation procedure featuring the use of a closed form expression along with a design chart which is illustrated by a worked example, to facilitate uptake in design practices.

Hillside RC barriers protected by gabion cushion layers are commonly used as passive defence measures to contain landslides and rockfalls. Gabions are expensive and require extensive maintenance. However, the design of gabion-free rockfall barriers cannot be implemented because of the lack of knowledge with the performance of a bare concrete surface when exposed to low-velocity impact hazards. The key contribution of this article is the adaptation, and experimental validation, of a theoretical model based on the principles of solid mechanics for predicting localised damage (denting and spalling) on a concrete surface. The theoretical model, which consists of closed-form expressions, can be executed using MATLAB or EXCEL for predicting the occurrence of denting and spalling in practical applications. The accuracy of predictions from the theoretical model has been validated by both large-scale impact testing and finite element simulations. The use of the model is illustrated with a worked example to facilitate the application of the presented methodology in engineering practices. The presented methodology has potential utility in the design of structural concrete which is exposed to an abrasive environment. The design of gabion-free RC rockfall barriers is an example of such utility.

A new type of moment-resisting bolted connection was developed for use in composite steel- concrete construction to connect composite open section steel beams to concrete filled steel square tubular columns. The connection was made possible using anchored blind bolts along with two through bolts. It was designed to act compositely with the in-situ reinforced concrete slab to achieve an enhanced stiffness and strength. The developed connection was incorporated in the design of a medium rise (five storey) commercial building which was located in low to medium seismicity regions. The lateral load resisting system for the design building consisted of moment resisting frames in two directions. A major full scale test on a sub-assembly of a perimeter moment-resisting frame of the model building was conducted to study the system behaviour incorporating the proposed connection. The behaviour of the proposed connection and its interaction with the floor slab under cyclic loading representing the earthquake events with return periods of 500 years and 2500 years was investigated. The proposed connection was categorized as semi rigid for unbraced frames based on the classification method presented in Eurocode 3. Furthermore, the proposed connection, composite with the floor slab, successfully provided adequate lateral load resistance for the model building.

This paper presents the findings of a recent reconnaissance survey of the reinforced concrete (RC) construction industry in Australia. The survey involved the review of the structural documentation of a set of case study buildings constructed in Australia. The types of walls and observed methods of detailing are documented. Upper and lower bound values for typical wall attributes have been presented which researchers can utilise to design laboratory test specimens or perform parametric computer studies, to ensure their study accurately represents real-world conditions. A literature review of experimental testing of the lateral in-plane capacity of RC walls is included. The literature review identified 81 experimental studies, in which 501 RC wall test specimens have been tested worldwide. It is shown that very little experimental studies have been performed on RC walls that match what is being constructed in Australia.

Screw anchors are gaining popularity in construction due to simplicity of their installation, ability to load them straight after the installation and ease of their removal. Existing models to predict the strength of screw anchors under tensile loading are based on the assumption that anchors are installed in mature concrete. This assumption is normally violated to escalate construction time. There is limited knowledge available in literature on behaviour of screw anchors in early age concrete. This research focuses on evaluating the behaviour of screw anchors installed and loaded in early age concrete. The relationship between the tensile and compressive strength of concrete as well as the ultimate strength of anchors and observed modes of failure are presented for a particular screw anchor based on 70 tensile tests. The experimental results have also been compared with the predicted values from the literature and specifications provided by the anchor manufacturer.

An important advancement in structural engineering in recent years has been the development of performance-based design (PBD). However, its application to cold-formed steel framed buildings remains largely unexplored. This paper presents the assessment of the bracing capacity of cold-formed steel stud bracing wall panels using a direct-displacement based design (DDBD) approach. The fundamentals of DDBD using equivalent damping, and inelastic displacement response spectra approaches are presented. These wall parameters needed for each approach are evaluated from experimental load–deflection response behaviour under quasi-static cyclic loading. Results obtained from the DDBD approach are compared with results from conventional non-linear time history analyses (NLTHA) to confirm the validity of the adopted approach. It is found that results estimated from DDBD method using inelastic displacement response spectra approach correlated much better with NLTHA results than the equivalent damping method.

Yield penetration or slip deformation is characterised by a rigid body rotation of the column associated with a gap opening at the column-foundation interface from the penetration of inelastic strain in the tensile reinforcement embedded in the foundation. The rigid-body end rotation increases the total drift significantly and has to be separated from flexural deformation obtained from curvature distribution over the column height. The yield penetration deformation model is developed based on a displacement-controlled principle using a new approach where the local steel strain as a function of the column global displacement is presented. In order to solve the strain incompatibility between steel and concrete, a correlation between compressive concrete strain and neutral axis depth is developed and a complete algorithm is presented that modifies the fibre cross section analysis to operate under curvature control as a function of top column displacement instead of strain control.

Domestic houses built of cold-formed steel (CFS) are typically supported laterally by wall panels that are made of braced steel studs. The behavior of those panels under cyclic strain reversals in an earthquake is too complex to analyse and is best evaluated by physical experimentation. Dynamic testings of full-scale wall specimens on a shaker table have been undertaken in previous studies but repeating those tests for different design configurations and base excitations can be very costly. This article presents seismic performance behavior of CFS wall panels based on monotonic, and cyclic, quasi-static tests followed by incremental dynamic analyses (IDA). Five accelerogram ensembles comprising artificial, and recorded, accelerograms, totaling 60 records, were employed for the nonlinear time-history analyses of single-degree-of-freedom models the hysteretic behavior of which had been calibrated to match with test results. Although IDA as a procedure has been around for a long time it has always been diffi...

Impact by windborne debris can cause severe and wide spread damage to building facades and other exposed installations. There is no clear guidance on how to estimate the amount of force generated by the impact of windborne debris when design codes of practices only provide estimates of the wind pressure. The model presented in this paper enables the value of the peak contact force generated by the impact of a piece of debris to be predicted. Results of calculations employing the derived relationships have been verified by comparison with experimental results across a wide range of impact scenarios. Once the impact action has been quantified the predicted impact force can be applied to the target in a quasi-static manner for predicting damage.

Recent research on steel moment-resisting connection between steel beams and concrete filled steel tubes has shown that there are considerable advantages to be obtained by anchoring the connection to the concrete infill within the tube using anchors in blind bolts. In the research reported here, extensive experimental tests and numerical analyses have been performed to study the anchorage behaviour of cogged deformed reinforcing bars within concrete filled circular steel tubes. This data in essential knowledge for the design of the steel connections that use anchored blind bolts, both for strength and stiffness. A series of pull-out tests were conducted using steel tubes with different diameter to thickness ratios under monotonic and cyclic loading. Both hoop strains and longitudinal strains in the tubes were measured together with applied load and slip. Various lead-in lengths before the bend and length of tailed extension after the bend were examined. These dimensions were limited by the dimensions of the steel tube and did not meet the requirements for "standard" cogs as specified in concrete standards such as AS 3600 and ACI 318. Nevertheless, all of the tested specimens failed by bar fracture outside the steel tubes. A comprehensive 3D Finite Element model was developed to simulate the pull-out tests. The FE model took into account material nonlinearities, deformations in reinforcing bars and interactions between different surfaces. The FE results were found to be in good agreement with experimental results. This model was then used to conduct parametric studies to investigate the influence of the confinement provided by the steel tube on the infilled concrete.

The point fixed glass façade system is popular and considered a more elegant façade option compared to the framed glass façade system mainly for storefront, walkways and lobby areas in buildings. Point fixed glass façade system is fixed to the support structure using special bolt fittings and structural spider arms. Generally, the racking performance of these systems is not considered at the design stage in low to moderate seismic region and the system may be vulnerable if there is insufficient in-plane drift capacity compared with the demand imposed during earthquakes and wind actions. A unique full-scale in-plane racking laboratory test on a typical point fixed glass façade system was conducted and a maximum drift of 2.1% was measured before catastrophic failure. Non-linear finite element models were then developed and benchmarked against experimental results. The experimental results and finite element analyses indicated that a significant amount of the drift capacity was attributed to the rigid body translation in the façade system connections at the built-in oversize holes provided for construction tolerances. In this article, the laboratory test setup and the experimental results are summarised, and the finite element modelling methodology and non-linear analysis approach undertaken using ANSYS for the experimental test are discussed along with number of parametric studies.

A displacement-based (DB) model is introduced in this article alongside its detailed derivations to predict the flexural response behaviour of a cantilevered reinforced concrete (RC) wall that is subjected to combined actions of boulder impact and sustained load (e.g. debris flow). In order to validate the model, a large-scale experiment was carried out by striking a 1.5 m tall, 3 m long and 0.23 m thick reinforced concrete wall using of two impactors weighing 280 kg and 435 kg to simulate different boulder impact intensities. A sustained load of 36 kN was applied to the wall using two prestressed custom-fabricated spring assemblies. Wall deflection and reinforcement tensile strain values measured from the experimental tests are shown to be within about 10–20% of predictions calculated from the proposed DB model. Errors of the predictions are consistently conservative across all the considered impact scenarios. These experimental findings are original given that no impact tests of the scale presented in this paper, which incorporate the effects of co-existing sustained lateral forces (e.g. debris flow), can be found in the literature. The proposed DB model was found to accurately predict both the deflection of the wall as well as the amount of tensile strain experienced by the reinforcement at the base of the wall. This paper concludes with a step-by-step design procedure that utilises the proposed DB model for designing RC rockfall barriers, which will be useful for practitioners aiming for a more optimised barrier design.

The literature available on structural performance of screw anchors is very limited. The most significant research on screw anchors was performed in the early 2000 when there was little variety of screw anchors. One of the findings of this early study was that the thread profile of screw anchors has little effect on their structural performance, such as the ultimate tensile capacity and failure mode. Currently, there is a much greater variety of screw anchors in the market, and they have gained much further popularity in construction industry. In this study, six types of screw anchors with different thread profiles and from different manufacturers were tested under tension. Given there is similarity between some of the anchors that are made by different manufacturers, the anchors were carefully selected in order to represent as many different thread patterns available in the international market as possible. Anchors were installed in two grades of concrete at two different embedment depths. The results from this study show that there is a much higher correlation between the tensile capacity of anchors and their thread profiles than the level suggested by the studies in the early 2000 that are currently considered by design standards. The effect of the thread profile of screw anchors on their ultimate tensile capacity, load-displacement curve and the related failure mode are further discussed in this paper.

Modular buildings are built using factory manufactured building units or modules that are transported and assembled on-site. Among the many different types of building units used, volumetric modules have the greatest potential to achieve complete building systems, where on-site work can be reduced to having only foundation, module assembly and the finishing of module-to-module interfaces. However, despite many reported benefits, the use of volumetric modules have some technical, logistical and regulatory issues that constrain its widespread application. The aims of this paper is to articulate two key technical issues that have been widely reported, namely, the lack of efficient structural systems for lateral load transfer and the lack of high-performance inter-module connectivity. Accordingly, a general overview regarding these two issues is presented that covers the behaviour of diaphragms in multi-story modular buildings and the essential characteristics required for inter-module connections. It is expected that inter-module connectivity should meet structural needs along with satisfying manufacturing and construction requirements. Brief descriptions of existing inter-module connecting systems that are available in both literature and the public domain including a critical review of those connections against the identified performance requirements are also presented. The outcomes of this paper are expected to assist in the future development and application of fully-modular superstructure construction systems for multi-story modular buildings.