@article {bnh-5625, title = {Vulnerability Functions for RC Shear Wall Buildings in Australia}, journal = {Earthquake Spectra}, volume = {35}, year = {2019}, month = {02/2019}, pages = {27}, chapter = {333-360}, abstract = {

This research investigates the development of analytical fragility functions for reinforced concrete shear wall buildings in Australia. A building stock for the city of Melbourne is used in conducting an assessment of these types of structures. The assessment uses the best information available for selecting the building parameters applicable to the low-to-moderate seismic region, site soil class, expected earthquake ground motions, and site response. The capacity spectrum method is used to derive vulnerability functions for low-, mid-, and high-rise reinforced concrete shear wall buildings. Although there is a paucity of earthquake damage data available in Australia, some comparisons are made using the results from the fragility functions derived here to the damage data from the Newcastle earthquake in 1989.

}, keywords = {buildings, earthquake, Emergency management, engineering}, doi = {10.1193/120717EQS251M}, url = {https://www.earthquakespectra.org/doi/abs/10.1193/120717EQS251M}, author = {Ryan D. Hoult and Helen M. Goldsworthy and Elisa Lumantarna} } @article {bnh-5157, title = {Plastic hinge analysis for lightly reinforced and unconfined concrete structural walls}, journal = {Bulletin of Earthquake Engineering}, volume = {16}, year = {2018}, month = {10/2018}, pages = {4825-4860}, chapter = {4825}, abstract = {

Poor performance of lightly reinforced and unconfined concrete structural walls have been observed in recent earthquake events. This research investigates the displacement capacity of such walls by comparing the results of a series of state-of-the-art finite element analyses for a range of different structural walls to that estimated using plastic hinge analyses. The common expressions used in estimating the yield curvature, yield displacement and plastic displacement are scrutinised for these types of walls. Some recommendations are given to improve the prediction of the displacement capacity of lightly reinforced and unconfined rectangular and C-shaped walls for flexural actions using a plastic hinge analysis. Importantly, a parameter has been recommended to be used in a {\textquotedblleft}modified{\textquotedblright} approach for estimating the nominal yield displacement of lightly reinforced concrete walls. Different expressions are also recommended depending on the amount of longitudinal reinforcement used in the wall in comparison to that required to initiate secondary cracking. This is important for providing better estimations of the displacement capacity of RC structural wall buildings in low-to-moderate seismic regions such that vulnerability studies can be conducted.

}, doi = {https://doi.org/10.1007/s10518-018-0369-x}, url = {https://link.springer.com/article/10.1007\%2Fs10518-018-0369-x}, author = {Ryan D. Hoult and Helen M. Goldsworthy and Elisa Lumantarna} } @article {bnh-5156, title = {Plastic hinge length for lightly reinforced C-shaped concrete walls}, journal = {Journal of Earthquake Engineering}, year = {2018}, month = {03/2018}, abstract = {

This research investigates the equivalent plastic hinge length of reinforced concrete C-shaped walls with reinforcement detailing typically found in low-to-moderate seismic regions. Reinforced concrete walls in these regions commonly have low amounts of longitudinal reinforcement and unconfined boundary regions, which have been shown to perform poorly in recent earthquake events. A series of state-of-the-art finite element analyses are undertaken to find the longitudinal strain distributions of low-rise, mid-rise, and high-rise C-shaped walls. The results of the equivalent plastic hinge lengths from the numerical investigation are shown to compare poorly to the predictions from some of the equations that currently exist in the literature. Subsequently, expressions are derived for the equivalent plastic hinge length for these types of walls and for the different modes of bending. The expressions derived from this research intend to improve the displacement capacity for these types of walls when using plastic hinge analyses.

}, doi = {https://doi.org/10.1080/13632469.2018.1453419}, url = {https://www.tandfonline.com/doi/abs/10.1080/13632469.2018.1453419}, author = {Ryan D. Hoult and Helen M. Goldsworthy and Elisa Lumantarna} } @article {bnh-3553, title = {Plastic hinge length for lightly reinforced rectangular concrete walls}, journal = {Journal of Earthquake Engineering}, year = {2017}, month = {05/2017}, pages = {1-32}, chapter = {1}, abstract = {

This research investigates the plastic hinge length in lightly reinforced rectangular walls typically found in regions of low-to-moderate seismicity. Poor performance has been exhibited by lightly reinforced concrete walls in past earthquake events. A series of finite element analyses have been carried out which demonstrate that if the longitudinal reinforcement ratio in the wall is below a certain threshold value, there will not be sufficient reinforcement to cause secondary cracking, and instead fracture of the longitudinal reinforcement at a single crack could occur. A plastic hinge length equation has been derived based on the results from the numerical simulations.

}, doi = {http://dx.doi.org/10.1080/13632469.2017.1286619}, url = {http://www.tandfonline.com/doi/full/10.1080/13632469.2017.1286619}, author = {Ryan D. Hoult and Helen M. Goldsworthy and Elisa Lumantarna} } @mastersthesis {bnh-4679, title = {Seismic assessment of reinforced concrete walls in Australia}, year = {2017}, month = {09/2017}, school = {University of Melbourne}, address = {Melbourne}, abstract = {

Some non-ductile reinforced concrete walls in buildings were observed to perform poorly in the 2011 Christchurch earthquake, with most of the lives lost from the event caused by the collapse of buildings that relied on these structural elements for lateral support. Reinforced concrete (RC) walls are widely used throughout the Australian building stock as the primary lateral support elements. It is possible that some of these structural elements would perform poorly in a very rare earthquake due to the low standard of detailing that is currently required in Australia, as well as the low earthquake return period that the Building Code of Australia stipulates for their design. The aim of this research has been to assess the seismic performance of reinforced concrete structural walls, both rectangular and C-shaped, in Australia, a region of low-to-moderate seismicity. The current Australian Standard for Earthquake Actions, AS 1170.4:2007, stipulates earthquake hazard values that are based on a seismic hazard map that is over two decades old. A probabilistic seismic hazard analysis was conducted for most of the capital cities in Australia using the AUS5 model to provide a more accurate prediction of seismic hazard in Australia. The results indicate that for some cities, such as Melbourne, the response spectrum is expected to be higher for large return periods in comparison to the design spectra derived using AS 1170.4:2007. Furthermore, a site response study was conducted using equivalent linear analyses to investigate the amplification of the soil response as classified in AS 1170.4:2007 using a range of ground motions that would be expected in Australia. The primary conclusions from the study showed that there can be a large dependency of the soil amplification on the intensity of the earthquake ground motions for the softer soil classes. Moreover, the low intensity ground motions resulted in a higher spectral shape factor for soil class Be and Ce in comparison to factors derived from the current AS 1170.4:2007. An investigation was undertaken to find the displacement capacity of rectangular lightly reinforced and unconfined walls using a finite element modelling (FEM) program, with emphasis on finding the equivalent plastic hinge length. A Secondary Cracking Model (SCM) was formulated, which is a simple, mathematical model that has the potential to predict if a RC wall has a sufficient longitudinal reinforcement ratio to enable {\textquotedblleft}secondary cracking{\textquotedblright} to occur. The SCM has been validated by comparison with results from the FEM analyses. Equivalent plastic hinge length equations were derived for the rectangular walls that were observed to form secondary cracking and a single, primary crack, and this can be used to predict the displacement capacity of these walls. This estimate of the displacement capacity assumes that the inelastic rotation that occurs over the inelastic region at the base of the wall can be modelled using an equivalent plastic hinge length over which the curvature is assumed to be a constant value. These estimates of the equivalent plastic hinge length are more appropriate for RC structural walls commonly found in Australia due to the parameters used in deriving them (e.g. mechanical properties of steel, longitudinal reinforcement ratio). Moreover, some expressions for the equivalent plastic hinge length that have derived by previous researchers were found to be inappropriate for the walls analysed in this research; these were particularly inaccurate for walls that do not have sufficient longitudinal reinforcement to force secondary cracks to form. The new expressions provide better estimates of the displacement capacity of lightly reinforced and unconfined walls when compared with recent experimental observations. One of the most widely used and popular cross-sections used in structural design of RC walls is the C-shaped section. There is a paucity of information available on the inelastic behaviour of such elements, and virtually no experimental data exists on non-rectangular concrete walls with inferior details commonly found in regions of low-to-moderate seismicity. An extensive number of nonlinear pushover analyses have been conducted based on FEM to investigate the seismic behaviour of C-shaped walls with detailing commonly found in Australia. Based on the FEM results, the SCM, that has been developed for rectangular walls, was found to be able to predict the potential of a single-crack forming in the walls. The direction of loading and mode of bending was found to be particularly important for the seismic performance of these walls. A non-ductile failure was observed for the majority of the walls investigated due to crushing of the unconfined concrete at the ends of the flanges in the governing direction of loading. Further analyses were conducted in the FEM program but with confined boundary ends to emphasise the importance of such structural detailing in allowing some plastic behaviour to be achieved for the governing direction of loading. The equivalent plastic hinge lengths derived from the extensive number of FEM analyses correlated poorly in comparison to the estimates from a number of expressions that exist in the literature, including a recently developed equation specifically for C-shaped walls. Therefore, equivalent plastic hinge lengths were derived from these results and for each direction of loading. A program has been written in MATLAB to derive vulnerability functions for low-rise, mid-rise and high-rise buildings in Australia that use structural walls as their lateral force-resisting system. The city of Melbourne was used as a template for conducting the analyses, and a dataset of thousands of buildings obtained from the National Exposure Information System (NEXIS) and Census of Land Use and Employment (CLUE) databases was included in the assessment. The displacement capacity of each of the buildings was estimated using a moment-curvature analysis followed by a plastic hinge analysis. A range of artificial earthquakes from GENQKE and real earthquakes from the PEER ground motion database on {\textquotedblleft}weathered bedrock{\textquotedblright} conditions were obtained. These ground motions were subsequently used in equivalent linear analyses using the program SHAKE2000 to find the site response at the surface of different soil columns from shear wave velocity profiles taken predominantly from sites around Melbourne. The National Regolith Site Classification Map was used to estimate the soil conditions underlying each of the building sites. The acceleration and displacement response spectra resulting from these ground motions were used to represent the seismic demand for different site conditions in the capacity spectrum method and to ultimately estimate the vulnerability of the buildings. Thus, vulnerability functions were derived from the results.

}, keywords = {AS3600; buildings, earthquake, emergency management., Intraplate, low-to-moderate}, url = {http://hdl.handle.net/11343/192443 }, author = {Ryan D. Hoult} } @conference {bnh-4407, title = {Seismic Assessment of the RC building stock of Melbourne from rare and very rare earthquake events}, booktitle = {Australian Earthquake Engineering Society 2017 Conference}, year = {2017}, month = {11/2017}, publisher = {Australian Earthquake Engineering Society}, organization = {Australian Earthquake Engineering Society}, address = {Canberra}, abstract = {

This paper focuses on a seismic vulnerability assessment of the Australian reinforced concrete structural (or shear) wall building stock using the Melbourne CBD as a case study. Each of the 1403 reinforced concrete buildings used in the assessment are assumed to be laterally supported by rectangular (peripheral) or C-shaped core walls. The assessment was conducted based on the Capacity Spectrum method, which involves a comparison between the capacity and demand curves in the form of acceleration-displacement response spectra. Plastic hinge analysis expressions were used to derive the capacity curves of the buildings. The 500-year ({\textquotedblleft}rare{\textquotedblright}) and 2500-year ({\textquotedblleft}very rare{\textquotedblright}) return period spectra derived from a Probabilistic Seismic Hazard Analysis for the city of Melbourne using the AUS5 earthquake recurrence model were used for the earthquake demand. The Australian Seismic Site Conditions Map from Geoscience Australia is used to find the expected site conditions for each building, while SHAKE-2000 is used to amplify the expected earthquake demand. The results show that only 34 (2.4\%) reinforced concrete buildings used in this assessment were deemed to reach the Collapse Prevention performance level for the 500-year return period event, whereas a total of 540 (38.5\%) buildings were estimated to reach this performance level for the 2500-year return period event.

}, author = {Ryan D. Hoult and Helen M. Goldsworthy and Elisa Lumantarna} } @article {bnh-3554, title = {Soil amplification in low-to-moderate seismic regions}, journal = {Bulletin of Earthquake Engineering}, volume = {15}, year = {2017}, month = {05/2017}, pages = {1945-1963}, chapter = {1945}, abstract = {

The results of a study that investigates potential revisions of the spectral shape factors used in standards in regions of low-to-moderate seismicity are presented here. Using an equivalent linear analysis, the investigation particularly focuses on the effects of seismic intensity associated with rare and very rare intraplate earthquake events on site response. The Pacific Earthquake Engineering Research Center ground motion database (PEER) is used in selecting appropriate acceleration-time histories for the intraplate region. The results are normalised for comparison with the current spectral shape factors given in the Australian Standards for Earthquake Actions AS 1170.4:2007, with some differences being observed. The dependency of site amplification on seismic intensity was only observed for soil classes Ce, De and Ee. The rock site of class Be had considerably higher response in the short period range relative to class Ee. The records from the PEER ground motion database were also used for comparison with the results from this study, using a modified normalisation approach. The results from this study correlate well with the records from PEER.

}, doi = {10.1007/s10518-016-0067-5}, url = {https://link.springer.com/article/10.1007/s10518-016-0067-5}, author = {Ryan D. Hoult and Elisa Lumantarna and Helen M. Goldsworthy} } @conference {bnh-3561, title = {Displacement Capacity of Lightly Reinforced Rectangular Concrete Walls}, booktitle = {Australian Earthquake Engineering Society 2016 Conference}, year = {2016}, month = {11/2016}, address = {Melbourne, Australia}, abstract = {

This paper investigates the displacement capacity of lightly reinforced rectangular walls. The design parameters and detailing of the walls considered in this study are typical of low-to-moderate seismic regions such as Australia. Obtaining accurate estimates of the displacement capacity of lightly reinforced walls is a vital step towards producing realistic estimates of fragility curves of RC buildings in low-to-moderate seismic regions. It is shown in this investigation that the nominal yield displacement capacity for reinforced concrete walls that have low amounts of longitudinal reinforcement can sometimes be overestimated using the existing equations. An alternative approach is proposed here which gives a better match with experimental and numerical results and is particularly important for the reinforced concrete walls that exhibit a single crack in the plastic hinge zone. An ultimate curvature equation is proposed for when a wall is estimated to form a single crack in the plastic hinge region. A plastic hinge length equation which has been specifically derived for these types of walls is also introduced to estimate the plastic displacement of the wall due to plastic rotation at the base. Experimental and finite element modelling results are used to compare the displacement capacity predictions.\ 

}, url = {https://www.researchgate.net/publication/310846070_Displacement_Capacity_of_Lightly_Reinforced_Rectangular_Concrete_Walls}, author = {Ryan D. Hoult and Helen M. Goldsworthy and Elisa Lumantarna} } @conference {bnh-3560, title = {Non-ductile seismic performance of reinforced concrete walls in Australia}, booktitle = {Australasian Structural Engineering Conference 2016}, year = {2016}, month = {11/2016}, address = {Brisbane, Australia}, abstract = {

Much of the Australian building stock comprises of reinforced concrete (RC) buildings that rely on RC walls or cores as their lateral load resisting system. Past research on the seismic behaviour of RC walls has primarily concentrated on highly reinforced and confined sections. However, there is a paucity of research focusing on lightly reinforced and unconfined sections that are commonly found in regions of low to moderate seismicity such as Australia. Moreover, some lightly reinforced concrete walls have been observed to perform poorly in recent earthquake events, with a single crack forming at the base within the plastic hinge region in contrast to the expected distributed cracks. This paper reports on an investigation into the seismic performance of rectangular walls with typical detailing and design parameters found in Australia. A simple model that can be used to predict the required amount of longitudinal reinforcement for the onset of secondary cracking is introduced. Finite element modelling results emphasise that a minimum amount of longitudinal reinforcement is required for secondary cracking to occur. Ultimately this will be useful for deriving a plastic hinge length that can be used for displacement capacity calculations of lightly reinforced walls.

}, url = {https://www.researchgate.net/publication/310728792_Non-ductile_seismic_performance_of_reinforced_concrete_walls_in_Australia}, author = {Ryan D. Hoult and Helen M. Goldsworthy and Elisa Lumantarna} } @conference {bnh-2075, title = {Improvements and difficulties associated with seismic assessment of infrastructure in Australia - peer viewed}, booktitle = {Adelaide Conference 2015}, year = {2015}, address = {Adelaide, Australia}, abstract = {

Research proceedings from the Bushfire and Natural Hazards CRC \& AFAC Conference in Adelaide, 1-3 September 2015.\ 

}, author = {Ryan D. Hoult and Helen M. Goldsworthy and Elisa Lumantarna} } @conference {bnh-2779, title = {Seismic assessment of non-ductile reinforced concrete C-shaped walls in Australia}, booktitle = {The Eighth International Structural Engineering and Construction Conference, Sydney, Australia.}, year = {2015}, month = {11/2015}, author = {Ryan D. Hoult and Elisa Lumantarna}, editor = {Helen M. Goldsworthy} } @conference {bnh-2778, title = {Torsional Displacement for Asymmetric Low-Rise Buildings with RC C-shaped Cores.}, booktitle = {Tenth Pacific Conference on Earthquake Engineering, Sydney, Australia.}, year = {2015}, author = {Ryan D. Hoult and Helen M. Goldsworthy and Elisa Lumantarna} } @conference {bnh-1891, title = {The 2012 Moe Earthquake and Earthquake Attenuation in South Eastern Australia}, booktitle = {Australian Earthquake Engineering Society Conference 2014}, year = {2014}, month = {11/2014}, abstract = {

In 2012 the state of Victoria experienced its largest earthquake in thirty years. The epicentre of the ML 5.4 earthquake is located near the town of Moe, within an area of elevated seismicity called the south-eastern seismic zone. The main event as well as over 200 aftershocks were recorded and located in a coordinated study by the University of Melbourne (UoM), Geoscience Australia (GA) and the Seismology Research Centre. At the time of the largest aftershock (ML 4.4), five instruments were operating within a 20km radius from the epicentre {\textendash} providing a unique near-source strong motion record. This paper presents the spectral acceleration response results captured from the two events at a range of distances. Estimations of the VS30 parameter have been obtained for the underlying soil structure of some of the recordings stations using available borehole data, soil classification maps, observation of the natural period and using the Horizontal to Vertical Spectral Ratio (HVSR) method. The acceleration response spectra calculated from the ground motions are thus at sites with estimated site-soil properties and these spectra have been compared with estimated values from potentially applicable attenuation models, including the latest NGA-West 2 functions released in 2014. These comparisons indicate the level of compatibility of spectra obtained using the actual data with predictions made using the different attenuation models. The results show a wide range of accuracy with the current attenuation models that are thought to be applicable to the region. This is of particular importance in assisting to select the most suitable attenuation models for future Probabilistic Seismic Hazard Analyses in eastern Australia (Non-Cratonic) and other regions of Australia; the results from this type of hazard analysis are highly dependent on the attenuation model chosen to represent the area of interest.

}, keywords = {Attenuation, Australia, GMPE, HVSR, Intraplate, Moe Earthquake, NGA-West 2, South Eastern}, author = {Ryan D. Hoult and Anita Amirsardari and D. Sandiford and Elisa Lumantarna and Helen M. Goldsworthy and G. Gibson and Michael Asten} } @conference {bnh-1889, title = {Deaggregating the differences between seismic hazard assessments at a single site}, booktitle = {Australian Earthquake Engineering Society Conference 2014}, year = {2014}, abstract = {

In the last few years there have been several probabilistic seismic hazard assessments (PSHA) of Adelaide. The resulting 500 year PGA obtained are 0.059, 0.067, 0.109 and 0.141. The differences between the first three are readily accounted for by choice of GMPE, how faults are included and differences in recurrence estimation, with each of these having a similar level of importance. As no GMPEs exist for the Mt Lofty and Flingers Ranges the choices of GMPEs were all based on geological analogies. The choice of at what weighting to include low attenuation, that is a stable continental crust, GMPE was most important. At a return period of 500 year the inclusion of faults was not necessarily significant. The choice of whether the faults behaved with Characteristic or Gutenberg-Richter recurrence statistics had the highest impact on the hazard with the choice of slip rate the next most important. A low slip rate Characteristic fault, while increasing the hazard for longer return periods (i.e. >=2500 years), results in only a minor increase at 500 years. The magnitude frequency distribution b-value for the four studies were 1.043, 0.88, 0.915 and 0.724. For the same activity in the magnitude range of 3.0 to 3.5, the activity level at M 6.0 is an order of magnitude higher for a b-value of 0.724 compared to a b-value of 1.043. This increase in activity rate of larger earthquakes significantly increases the hazard. The average of the first three studies is 0.078{\textpm}0.022 (0.056 {\textendash}0.100) g. This range is reflecting the intrinsic uncertainty in calculating PSHAs where many of the inputs are poorly constrained. The results for the highest hazard level PSHA study (i.e. 0.141g) can be explained by their use of a low b-value (i.e. 0.724).

}, author = {M. Leonard and Ryan D. Hoult and Somerville, P and G. Gibson and D. Sandiford and Helen M. Goldsworthy and Elisa Lumantarna and S. Spiliopoulos} } @conference {bnh-1890, title = {Seismic Performance of Typical C-Shaped Reinforced Concrete Shear Cores in Australia}, booktitle = {Australian Earthquake Engineering Society Conference 2014}, year = {2014}, abstract = {

Limited-ductile reinforced concrete structures have been known to perform poorly when subjected to large seismic ground motions. Many buildings in Australia rely on reinforced concrete shear-cores as their primary lateral load resiting system, but these are only required to have a low standard of detailing as per the current concrete material standards AS 3600. While there is some literature available on the numerical and analytical modelling of rectangular shaped shear walls, non-rectangular shear walls have not been extensively analysed. {\textquotedblleft}C-shaped{\textquotedblright} shear walls are commonly found enclosing a service core, lifts, stairs and toilets. This paper presents a study which looks at the seismic performance of C-shaped shear walls with different steel reinforcement ratios for low, mid and high-rise buildings. The current earthquake actions code AS 1170.4 has been used for a preliminary design of the walls using a force-based design approach within which the intention is to satisfy the performance objective of life safety in a 500 year return period earthquake design level event in Melbourne. The displacement capacity of these different core walls has been calculated using a Displacement-Based Assessment procedure and complemented with finite element modelling program SeismoStruct. The results of a probabilistic seismic hazard analysis (PSHA) using the AUS5 recurrence model that has been conducted for the city of Melbourne has been used to calculate more accurate predictions of the displacement response spectra for 500 and 2500-year return periods. The C-shaped core walls have then been assessed by comparing the displacement capacity at different structural performance limit states to the displacement spectra derived from the current earthquake loading code AS 1170.4 and the spectra results from the PSHA for both the 500 and 2500-year return periods and for soil classes Be and De.

}, keywords = {AUS5, Australia, capacity, concrete, Core, displacement-based, earthquake, limited-ductile, low-to-moderate, PSHA, seismicity, spectra, unconfined, Walls}, author = {Ryan D. Hoult and Helen M. Goldsworthy and Elisa Lumantarna} } @conference {bnh-1888, title = {Ground Motion Modelling and Response Spectra for Australian Earthquakes}, booktitle = {Australian Earthquake Engineering Society Conference 2013}, year = {2013}, abstract = {

Due to the relatively low frequency of large earthquake events in Australia, and the\ inadequacy of recorded data, engineering seismologists commonly adapt ground motion\ prediction equations (GMPEs) developed from other regions with similar conditions to the\ Australian continent for the calculation of acceleration and displacement response. Recent\ improvements using high quality recorded data have given rise to Next Generation\ Attenuation (NGA) ground motion models. However, these NGA ground motion models\ show significant discrepancies with other ground motion prediction equations that have been\ developed and used in Australia, and these include the models that have helped establish the\ new Australian Earthquake Hazard Map. This paper presents a study which looks at the\ possibility of a very rare earthquake occurring at close proximity to the Sydney CBD. The\ suitability of use in Australia of the various available ground motion models is discussed, and\ some of these models are used to calculate the acceleration and displacement response\ spectra. There is a large discrepancy observed between the western North American derived\ NGAs and some of the other Australian GMPEs. The SHAKE2000 computer program was\ used to illustrate amplification of response at a soil site relative to that at a rock site. An\ NGA-West 2 model, that will be available in 2013, is also shown to illustrate improvements\ to the original 2008 NGA models.

}, keywords = {Australian earthquakes, ground motion prediction equations, intra-plate, Next generation attenuation, NGA-West 2, SHAKE2000}, author = {Ryan D. Hoult and Elisa Lumantarna and Helen M. Goldsworthy} }