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Code response spectrum models, which are used widely in the earthquake-resistant design of buildings, are simple to apply but they do not necessarily represent the real behavior of an earthquake. A code response spectrum model typically incorporates ground motion behavior in a diversity of earthquake scenarios affecting the site and does not represent any specific earthquake scenario. The soil amplification phenomenon is also poorly represented, as the current site classification scheme contains little information over the potential dynamic response behavior of the soil sediments. Site-specific response spectra have the merit of much more accurately representing real behavior. The improvement in accuracy can be translated into significant potential cost savings. Despite all the potential merits of adopting site-specific response spectra, few design engineers make use of these code provisions that have been around for a long time. This lack of uptake of the procedure by structural designers is related to the absence of a coherent set of detailed guidelines to facilitate practical applications. To fill in this knowledge gap, this paper aims at explaining the procedure in detail for generating site-specific response spectra for the seismic design or assessment of buildings. Surface ground motion accelerograms generated from the procedure can also be employed for nonlinear time-history analyses where necessary. A case study is presented to illustrate the procedure in a step-by-step manner.

This paper presents a statistical analysis of the actual mean material properties for typical grades of concrete and reinforcement available in Australia. The analysis was performed using a database of 3,447 concrete cylinder test results and 15,201 reinforcement tensile test results. The test results were taken over a period from 2009 to 2021. The paper provides a summary of the mean values and respective coefficient of variation values for the different grades of concrete and reinforcement that make up the database. Distinctive manufacturing trends and variability between suppliers were observed for reinforcement samples and appropriate recommendations have been proposed. Researchers or designers can adopt these values to undertake probabilistic assessments of RC structures. The paper also provides recommendations for mean material properties for the purpose of undertaking non-linear analysis of RC structures. The database of test results also includes early age strength data for concrete, which have been used to provide recommendations for predicting the early age strength of various standard grades of concrete available in Australia. The paper also presents an assessment of the theoretical characteristic values from the database for the various grades of reinforcement and concrete and how they compare to respective specified code requirements.

Displacement-based methods, such as a non-linear static pushover analysis (e.g. the capacity spectrum method), have many advantages compared to traditional force-based design methods. However, implementing a non-linear analysis and design method in accordance with the Australian Standard for concrete structures (AS 3600) introduces many difficult technical issues into the design, of which the standard provides little guidance. The aim of this study is to provide a framework and general guidance for designers who wish to perform non-linear displacement-based analysis methods for RC wall buildings. The paper will present how these methods can be used in accordance with the Australian Standard for earthquake actions (AS 1170.4) to assess seismic compliance and then provide recommendations for the requirements stipulated by AS 3600, which includes an experimentally validated tension stiffening model, nonlinear stress-strain material curves, mean material properties and material strain limits. The paper is concluded with a case study example of how a displacement-based seismic assessment can be performed using a typical case study building.

This paper presents an application of the Conditional Mean Spectrum (CMS) methodology for sourcing accelerogram records for use in dynamic analyses of structures in intraplate regions of lower seis...

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 facilitate the design of structural elements that are vulnerable to collision hazards, simple closed-form expressions have been stipulated in major codes of practice for quantifying the associated design impact actions. It is revealed in this article that the peak deflections from impact loading predicted using the closed-form expressions found in many of the major codes of practice around the world are in gross disagreement with observations from experimental testing in literature. This observation was following the review and assessment of the test results recorded from 68 dynamic experiments on reinforced concrete (RC) beams. The articles presenting these test results have not proposed new analytical models for guiding predictions nor have evaluated any existing analytical models. To fill this knowledge gap, this article proposes new closed-form expressions that were developed using displacement-based design principles and validated against 68 test results from literature, which showed the expressions provide accurate predictions of the deflection demand on RC beams subject to impact actions.

Columns in building frame systems are subjected to the combined action of bidirectional horizontal loading and axial load variation during an earthquake. Whilst the behaviour of RC columns under un...

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.

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 study aimed to quantitatively develop realistic quasi-static loading protocols for simulating bidirectional cyclic actions and axial load variation on building columns in a way that is...

The seismic behavior of ductile high-strength RC (HSRC) columns that are constructed in regions of high seismicity is well understood due to a number of experimental studies conducted over ...

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 ...

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.

This paper reviews the current seismic design procedures for reinforced concrete buildings in Australia, with direct reference to the Australian earthquake loading code, AS 1170.4 and Australian co...

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.

Landslides and rockfalls are major hazards in mountainous regions. The level of hazard tends to be on the rise amid climate change. Rockfall barriers are constructed as protective measures to protect lives and built infrastructure. Landslide hazard can be accentuated by the impact of boulders on protective installations such as reinforced concrete barriers. Impact action can be divided into localised and global actions. Localised actions are controlled by the amount of contact force generated by the impact. Contact force can be many times higher than quasi-static force which can cause permanent damage to the structure. A large scale experimental investigation was carried out on a reinforced concrete barrier with 280 and 1020 kg hemispherical headed steel impactors. Localised effects on concrete barrier at different impact locations have also been investigated. Experimental data recorded from large scale test will be presented in this paper. It is observed that the amount of contact force at different impact locations are not the same although the amount of delivered impact energy is the same. At high velocity of impact and hence high rate of loading shear failure can be the dominating failure mechanism.

Collapse of one or more columns under severe ground motions leads to redistribution of internal forces in a reinforced concrete (RC) frame system, and thus, may serve as a precursor to the progressive collapse of the whole structure. While axial load collapse behavior of limited ductile normal-strength reinforced concrete (NSRC) columns has been widely investigated, very few experimental studies explored the collapse behavior of limited ductile high-strength reinforced concrete (HSRC) columns. This paper presents the details of an ongoing experimental testing program to investigate the collapse behavior of limited-ductile HSRC columns prevalent in regions of low to moderate seismicity. Axial load ratio, transverse reinforcement ratio, concrete compressive strength and direction of loading are the variables of the study. The paper presents preliminary results of the testing program, in which two limited ductile high-strength RC columns are tested under variable axial load ratios.

Sustainability necessitates the protection of infrastructure from any kind of deterioration over the life cycle of the asset. Deterioration in the capacity of reinforced concrete (RC) infrastructure (e.g., bridges, buildings, etc.) may result from localised damage sustained during extreme loading scenarios, such as earthquakes, hurricanes or tsunamis. In addition, factors such as the corrosion of rebars or ageing may also deteriorate or degrade the capacity of an RC column, thereby necessitating immediate strengthening to either extend or ensure its design life is not limited. The aim of this paper is to provide a state-of-the-art review of various strengthening and repair methods for RC columns proposed by different researchers in the last two decades. The scope of this review paper is limited to jacketing techniques for strengthening and/or repairing both normal- and high-strength RC columns. The paper also identifies potential research gaps and outlines the future direction of research into the strengthening and repair of RC columns.

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.

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.

Current detailing practices in regions of low to moderate seismicity, which are typically intraplate regions, result in limited to moderately ductile reinforced concrete (RC) columns that are characterised by relatively low drift capacities in contrast to ductile RC columns in regions of higher seismicity. Rare or very rare seismic events occurring in these intraplate regions may impose larger drift demands on such columns, thereby making them vulnerable to collapse. This chapter presents a piecewise lateral force-displacement model that can serve as a tool for estimating the drift capacity of RC columns that can be used to check if the RC columns in the building are meeting the seismic performance objectives

This paper endeavors to enhance the understanding of the non-linear force-displacement hysteretic behavior of reinforced concrete (RC) columns subjected to bidirectional earthquake actions with different loading paths and magnitudes of lateral displacement in the two axes. RC column testing in literature has traditionally been focused towards the unidirectional testing of both normal and high strength concrete columns or the bidirectional testing of normal strength concrete columns only. This study will address this important knowledge gap by experimentally investigating the biaxial lateral capacity of high-strength RC columns with limited ductile detailing. The results of this experimental study and other previous studies are also used to develop a simplified model for predicting the non-linear backbone force-displacement behavior of RC columns. The paper will firstly present the six full-scale column specimens, the test setup, and the loading procedure. The test results will then be presented and analyzed. Three different bidirectional loading protocols were adopted to study the effects of loading history. The important effects of axial load ratio on the collapse behavior (i.e. maximum drift) are also examined in detail. The paper will conclude with an overview of the proposed backbone model for predicting the force-drift behavior of RC columns subjected to bidirectional loading.

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.

This paper presents an overview of how designers could undertake a displacement-based seismic assessment of rectangular reinforced concrete (RC) walls in accordance with Australian codes and standards. RC detailing in Australia generally results in a limited ductile RC structure and as such will be the focus of this paper. The various seismic performance objectives set out by Australian codes and standards are summarised herein. The paper will outline how a non-linear static pushover analysis could be performed in accordance with the Australian concrete structures standard to determine the force-displacement response curve of a rectangular wall. Mean stress-strain curves representing the actual performance of reinforcement and concrete are presented. The method presented for determining the force-displacement response curve is validated against large scale laboratory test results with very good correlation shown. The paper concludes with a parametric study of rectangular walls looking at how the overstrength and displacement ductility vary with changes in the axial load ratio, effective height, concrete strength and vertical reinforcement ratio.