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This article presents a new approach to construct reduced-order models for large nonlinear circuits excited by periodical or quasi-periodical sources. The key feature in the constructed reduced model is that it enables, through solving a much smaller system, tracing the variations in the periodical steady-state response of the original circuit with regards to variations in selected design parameters. The proposed approach is based on the notion of using discrete empirical interpolation to project the nonlinear operator of the circuit equation onto a smaller subspace. In addition, the original system equations are projected onto the subspace spanned by the first few derivatives of the solution with respect to the selected design parameters. Computational savings are made possible through solving a reduced system of equations instead of the full system. Numerical examples are presented to validate the accuracy and efficiency of the proposed approach.

Finite element analysis (FEA) has been used as a successful supplement to experimental testing in various studies for simulation of anchorage behaviour. Throughout the years, researchers have employed different modelling techniques in various FEA packages to capture the behaviour of post-installed anchors. However, the vast amount of knowledge accrued is yet to be reviewed. This article critically reviews all aspects of FEA from pre-processing to post-processing and provides a comprehensive review of published literature on FEA studies for predicting the behaviour of post-installed anchorage systems. Most current efforts focus on investigating failure mechanism of anchors in uncracked concrete under tensile loading. Findings show that developing finite element model for post-installed anchorage in concrete is very challenging due to complex geometrical configuration of anchors, difficulty in modelling concrete–anchor interface and lack of reliable information on selecting material properties and parameters. The analysis identified key gaps in research related to the effect of geometrical simplification, anchor subjected to dynamic loading and anchor performance in cracked concrete which needs attention in future research. This review article is a valuable resource in facilitating future research on assessing the performance of post-installed anchorage in concrete with FEA.

Reliable performance of the electricity distribution networks is critical to avoid outages and disruptions which may lead to substantial economic losses. Some of the important components of the electricity distribution networks include overhead cables, utility poles, cross-arms, substations, and transformers. These components are subjected to deterioration with aging and pose risks of failure creating safety concerns, specially under extreme weather conditions. Efficient maintenance and the use of accurate condition assessment techniques to monitor the integrity of the aforementioned components are key factors to be considered in managing the electricity distribution assets. This article presents a review of different condition assessment techniques employed for monitoring the electricity distribution infrastructure. The conventional inspection techniques and advancements in non-destructive testing methods are discussed outlining the relative advantages and disadvantages. Other than the normal failures of distribution infrastructure due to component ageing, unexpected and less frequent extreme weather events can have significant impacts on the resilience of the electrical power infrastructure. Thus, the effects of extreme weather conditions on the reliability of the electricity distribution networks and the failure rates of assets are reviewed in this study. Further, the maintenance and decision-making approaches implemented in the power distribution networks are also discussed.

There is a need to improve the Australian conformance practice for construction products. This paper presents an overview of the current operating environment of Australia and discusses the differe...

Microwave modeling and simulation are essential to designing microwave circuits and systems. Although fundamental concepts and approaches for modeling and simulation are mature, the drive to higher frequencies, tighter design margins, and more functionality/complexity of circuits continue to defy the capabilities of existing modeling and simulation methods. Newer algorithms are being developed to address the speed, accuracy and robustness of design algorithms. Coupled with the advent of more powerful computers and algorithms, microwave design automations are solving much more complex problems in much shorter time than previously imaginable. This paper describes the advances and state-of-the-art in automated modeling and simulation. Automated data-driven modeling approaches covering data sampling/generation, model structure adaptation, and model training/validation are described. Simulation of nonlinear microwave circuits is described covering formulations of simulation equations and advanced solution algorithms addressing problem size, convergence speed and solution accuracy. The descriptions highlight fundamental concepts, advanced methodologies, and future trends of development.

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.

Collapse prevention is the primary objective of earthquake-resistant design of structures; hence, the probability of collapse should be taken as a crucial performance indicator for risk-based desig...

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 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.

Due to space limitations, screw anchors may be used closer to the edge of the substrate than distances recommended by manufacturers, e.g. to connect bottom plates, base plates or handrails in resid...

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.

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...

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 ...

One of 2019's biggest scientific challenges is the coronavirus disease (COVID-19). The current COVID-19 epidemic is still a point of interest of all researchers from every field in the hope of finding a way to have it under control. COVID-19 vaccine development is a lengthy procedure that requires several clinical studies to prove its efficacy and overcome the virus mutations. Personal Protective Equipment (PPE) as masks and gloves are essential for moving the battle out of one's body. Developing a highly efficient PPE is crucial, not only to reduce the spread of virus, but also to protect people who work at the frontline. Virus infection is one of the most serious public health problems facing the world today. Between now and then, several antiviral medicines have been tested to determine their effectiveness as prospective COVID-19 treatments. The rise of viral resistance, as well as the adverse effects associated with antiviral medications, are posing further hurdles, resulting in a decrease in their efficiency as antiviral treatments. This opens the possibility for developing an alternative antiviral material that is both safe and effective. When it comes to their potential to destroy a wide range of viruses, silver nanoparticles (Ag-NPs) laden fiber mats have emerged as a novel antiviral platform, according to the findings of the current study. In the past, Ag-NPs have been extensively examined for their antibacterial properties against a wide range of microorganisms. Their ability to combat hepatitis B and HIV has also been demonstrated to be encouraging, as has their ability to inhibit other viruses such as herpes simplex, monkey pox, and respiratory syncytial virus. Here, we tested the potential effect of silver nanoparticles as an alternative antiviral therapeutic based on their unique properties. When compared to imitative antivirals, elemental silver nanoparticles have the ability to attack many virus sites, reducing the likelihood of the virus developing resistance. Our group has been developing silver nanoparticles loaded on toilet paper seat sheets, cellulose membranes, polymer dressings, and cotton textiles in response to the persistent issue. The new generation of fiber mats will be thoroughly described and tested against SARS-CoV-2 virus. SEM, EDS, TEM, and DLS will be utilized to identify the shape of our fibers and estimate the particle size of the embedded nanoparticles.

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.

The Hunt and Crossley model has been demonstrated to give accurate predictions of contact force generated by the impact of a solid object. The simulated contact force values have been demonstrated to match closely with experimental results as reported in the literature. However, derivation of the expression for finding the value of the damping coefficient has never been presented. The writing of this paper was motivated by the need to fill in the important knowledge gap.

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 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...

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.

Numerical modelling techniques enable forcing function at the point of contact in a hail impact to be predicted, but many models available in commercial software have not been verified by experiments. A recently developed deterministic model is only able to simulate the impact action of an idealised spherical hailstone. Results recorded from the impact testing of non-spherical simulated hail ice specimens show wide scatters and are different to spherical specimens. A stochastic model has been developed in this study to incorporate the variability of the modelling parameters representing the behaviour of non-spherical ice specimens and to generate time histories of contact force for given impact scenarios. A probabilistic model which was developed previously to provide predictions of the distribution of the size of hailstones in a severe category hailstorm has also been further developed to provide predictions of the maximum contact force values in probabilistic terms. For any given pre-defined forcing function denting into the surface of a steel plate can be estimated by finite element analysis or experimentally on a test machine. The new knowledge base introduced in this paper can be used by manufacturers and designers to re-assess existing products and in making improvements to future installations taking into account cost–benefit considerations.

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.

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.

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.

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.

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.

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.

The coronavirus disease 2019 (COVID-19) emerged as a worldwide challenge to researchers and scientists. All research communities are working relentlessly in their labs hoping to find cure for the current COVID-19 pandemic. Developing a new vaccine for COVID-19 is not down on the road, it is a long process that needs numerous clinical trials. Moving the battle out of the body requires personal protective equipment (PPE), particularly masks and gloves. Together, they will limit spread of the virus, whether by reinforcing the PPE and developing synergistic antiviral coatings or finding a cure and vaccine to COVID-19. Virus infection is one of the major global health challenges. In the meantime, several antiviral agents have been under testing to assess their efficacy as potential therapies for COVID-19. The viral resistance and the side effects associated with antiviral agents are adding more challenges, which resulted in lagging of their effectiveness as antiviral treatment. This opens the door for the development of safe and potent alternative antiviral drugs. In the current study, silver nanoparticles loaded fiber mat have emerged as a new antiviral platform in terms of their capability to deactivate a wide array of viruses. Silver nanoparticles have been studied exhaustively for their antimicrobial activity against wide-ranging of bacteria. Besides they have also shown promising activity versus several types of viruses including hepatitis B, human immunodeficiency virus (HIV), herpes simplex, monkey pox, and respiratory syncytial virus. Silver nanoparticles provide an alternative route as a new antiviral therapy. Interestingly, silver metals have the power to attack multiple targets in the virus, which results in diminishing its possibility to develop resistance as compared to imitative antivirals. Considering the ongoing challenge, our lab has been preparing silver nanoparticles loaded on filter papers, cellulose membrane, polymer dressings, and cotton fabrics. These new generation of fiber mats will be fully characterized and tested against several viruses. Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS) will be used to determine the morphology of our fibers and measure the particle size of the embedded nanoparticles.

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.

This paper presents the experimental testing and results of a recent study into panel-to-panel connections for jointed precast concrete building cores. Panel-to-panel connections are typically used to transfer vertical shear forces between adjacent panels to allow the individual panels to act as one combined composite cross-section. The experimental program consisted of three specimens, each constructed using a different type of connection. The first specimen was the ‘baseline’ specimen and was constructed using ‘industry standard’ welded stitch plate (WSP) connections. The second and third specimen were constructing using two new prototype connections, which were developed by the authors and are referred to as grouted panel pocket (GPP) and post tensioned corbel (PTC) connections. These connections were developed such that precast concrete building cores could be constructed without the use of wet joints or site welding, which are both costly aspects in precast wall construction. The experimental assessment showed both connections were stronger and stiffer than the baseline WSP connection. The paper is concluded with a detailed overview of the critical failure mechanism of each connection and the development of respective design models that could be used to predict the design performance of the connections.