@article {bnh-7482, title = {In-plane shear testing of unreinforced masonry walls and comparison with FEA and NZSEE predictions}, volume = {5}, year = {2020}, month = {01/2020}, abstract = {

The present study was conducted to investigate the global and local in-plane response of perforated URM walls under earthquake loading, based on observations of damage from previous earthquakes. To do so, full-scale cyclic in-plane testing of URM walls with an arched opening which were designed to represent walls in heritage URM structures in Australia was performed. The study investigated the behaviour of both pier and spandrel elements within the walls. Emphasis was also given to the position of walls within a multi-storey building by varying the pre-compression loads (representing gravity loads) on the walls. The tested walls were then simulated using nonlinear finite element analyses (FEA) where simplified micro-modelling (crack-shear-crush) approaches were used to analyse the wall behaviour. Finally, the shear capacities and the failure modes of the walls obtained from the experimental tests and FE analyses were compared to the proposed New Zealand Society for Earthquake Engineering (NZSEE) predictions.

}, keywords = {cyclic testing, FEA, finite element analyses, in-plane shear behaviour, NZSEE, unreinforced masonry, URM}, doi = {https://doi.org/10.1504/IJMRI.2020.104845}, url = {https://www.inderscienceonline.com/doi/abs/10.1504/IJMRI.2020.104845}, author = {Milon Howlader and Mark Masia and Michael Griffith} } @article {bnh-5487, title = {Final report on vulnerability of as-built and retrofitted URM buildings}, number = {474}, year = {2019}, month = {03/2019}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

As reported in the previous project reports {\textquotedblleft}Fragility Curves for URM Buildings{\textquotedblright} (Derakhshan and Griffith, 2018) and {\textquotedblleft}Fragility Curves for Retrofitted URM Buildings{\textquotedblright} (Vaculik and Griffith, 2018), fragility curves are an important tool for estimating the economic loss due to earthquakes. In this report, Fragility is used as a proxy for Vulnerability.\  As a follow-up to the work presented in the previous two reports, this report presents fragility curves for {\textquoteleft}as-is{\textquoteright} and {\textquoteleft}retrofitted{\textquoteright} URM buildings in terms of {\textquoteleft}probability of exceedance{\textquoteright} versus {\textquoteleft}peak ground acceleration{\textquoteright} (PGA) for four damage ratios, D1 {\textendash} D4. With this additional information, it will be possible to estimate the reduced damage due to seismic retrofit for cost-benefit analyses for a range of earthquake scenarios in order to ensure cost-effective seismic strengthening policy.

With this in mind, the remainder of this report should be treated as an addendum to the previous two project reports (Derakhshan and Griffith, and Vaculik and Griffith, 2018), hereafter referred to as the August and October 2018 reports.

In the October 2018 report, we described the methodology used to produce empirically-based fragility curves for seismically strengthened URM buildings on the basis of performance reported for 78 heritage-listed buildings in Christchurch during the 2010 and 2011 earthquake sequence.\ 

Empirical fragility curves for the global damage of strengthened buildings have been derived using the simplifying assumption that the PGA to cause a particular probability of a given damage state in a strengthened building can be obtained as a scalar multiple of the probability to cause the same damage state in the unstrengthened building. On the basis of this assumption, PGA scaling multipliers are calibrated which can be used to apply a rightward shift to the unstrengthened building curves (from the August 2018 report) to produce the corresponding curves for strengthened buildings. These multipliers were calibrated using the Christchurch earthquake damage data for two levels of retrofit. It was found that a multiplier of 1.4 produces good agreement for buildings with a full building strengthening level of retrofit, and a multiplier of 1.1 for buildings with partial or incomplete strengthening.\  These relatively low values are a result of the fact that the unreinforced masonry buildings in Christchurch were retrofitted as many as 50 years ago when seismic strengthening technologies for URM buildings were in their infancy.\  With advances in our understanding and improved retrofit technologies of today, where the seismic strengthening techniques have been experimentally validated, slightly higher scaling multipliers of 1.25 and 1.6 are justified and were used to generate the fragility curves for partial and full seismic retrofit, respectively.

}, keywords = {Built Environment, earthquake, URM}, author = {Jaroslav Vaculik and Michael Griffith} } @conference {bnh-6384, title = {Modelling the vulnerability of old URM buildings and the benefit of retrofit}, booktitle = {Australian Earthquake Engineering Society 2019 Conference}, year = {2019}, month = {12/2019}, abstract = {

The Shire of York is partnering with the WA Department of Fire and Emergency Services (DFES), the University of Adelaide and Geoscience Australia in a collaborative project that will examine the opportunities for reducing the vulnerability of the township of York to a major earthquake. The project forms part of the Bushfire and Natural Hazards Collaborative Research Centre (BNHCRC) project {\textquotedblleft}Cost-effective Mitigation Strategy Development for Building Related Earthquake Risk{\textquotedblright}. The township of York has a number of valuable historical buildings that contribute greatly to the town{\textquoteright}s economic prosperity and, at the same time, are vulnerable to earthquakes.

One of the benefits of retrofitting an old building is the reduction in physical building repair required following a damaging earthquake. To evaluate this benefit it is necessary to know the vulnerability of the unmitigated building and how this changes following retrofit.

This paper describes the approach taken to quantitatively estimate the vulnerability of unmitigated and retrofitted pre-WW1 unreinforced masonry (URM)buildings typical of the buildings found in York. Challenges in estimating vulnerability are discussed. Vulnerability curves are presented for one of six generic building types subjected to a range of retrofit scenarios and the economic benefit of each retrofit scenario is presented and discussed.

}, keywords = {earthquake, retrofit, URM, Vulnerability}, url = {https://aees.org.au/wp-content/uploads/2019/12/02-Mark-Edwards.pdf}, author = {Mark Edwards and Martin Wehner and Hyeuk Ryu and Michael Griffith and Jaroslav Vaculik} }