michael griffith

Equivalent frame modelling of an unreinforced masonry building with flexible diaphragms

Publisher: New Zealand Society for Earthquake Engineering

Date: 30-09-2016

DOI: 10.5459/BNZSEE.49.3.234-244

Abstract: A case study was conducted to investigate the applicability of the equivalent frame modelling for the nonlinear time-history analysis of unreinforced masonry buildings with flexible diaphragms. The dynamic responses calculated from the equivalent frame models were compared against shake table test results of a full-scale two-storey stone masonry building. The investigated modelling approach reflected the simplifications commonly assumed for the global analysis of buildings namely, considering the diaphragms to behave elastically and neglecting the stiffness and strength contributions of the out-of-plane responding walls. The sensitivity of the analysis to different idealisations of the equivalent frame, as well as to the diaphragm stiffness values, were also investigated. Discussions are provided on the accuracies and limitations of the investigated modelling approach, which may serve as a useful guidance for practical application.

Seismic analysis of in-plane loaded walls in unreinforced masonry buildings with flexible diaphragms

Publisher: New Zealand Society for Earthquake Engineering

Date: 31-12-2014

DOI: 10.5459/BNZSEE.47.4.275-289

Abstract: It is well recognised that the dynamic response of unreinforced masonry buildings with flexible timber diaphragms typically contains multiple dominant modes associated with the excitations of the diaphragms and the in-plane walls. Existing linear analysis methods for this type of structure commonly account for the multi-mode behaviour by assuming the independent vibrations of the in-plane loaded walls (in-plane walls) and the diaphragms. Specifically, the in-plane walls are considered to be rigid and the unmodified ground motion is assumed to be transmitted up the walls to the diaphragm ends. While this assumption may be appropriate for many low-rise unreinforced masonry buildings, neglecting the dynamic interaction between the diaphragms and the in-plane walls can lead to unreliable predictions of seismic demands. An alternative analysis approach is proposed in this paper, based on the mode properties of a system in which (1) the mass ratios between the diaphragms and the in-plane wall are the same at all levels, and (2) the periods of the diaphragms are the same at all levels. It is proposed that under these conditions, two modes are typically sufficient to obtain the peak seismic demands of the in-plane walls in elastically responding low-rise regular buildings. The applicability of the two-mode analysis approach is assessed for more general diaphragm configurations by sensitivity analysis, and the limitations are identified. The two-mode approach is then used to derive a response modification factor, which may be used in conjunction with a linear static procedure in the seismic assessment of buildings with flexible diaphragms.

Detailed seismic assessment and improvement procedure for vintage flexible timber diaphragms

Publisher: New Zealand Society for Earthquake Engineering

Date: 30-06-2014

DOI: 10.5459/BNZSEE.47.2.97-118

Abstract: Currently there is little guidance available on an experimentally-validated detailed seismic assessment procedure for vintage flexible timber diaphragms such as are routinely encountered in New Zealand unreinforced masonry buildings. The results from recent testing of full-scale diaphragms are presented and interpreted with particular attention given to the definition of shear stiffness and shear strength values, whilst acknowledging that the recommendations derive from a small data set. References are provided to information previously published elsewhere to justify the theoretical framework adopted, and the procedure is linked to ASCE 41-13 for guidance regarding diaphragm scenarios that have not been studied by the authors. A procedure is provided to account for the effects on diaphragm response of supplementary stiffness due to masonry end walls. The performance of several diaphragms that were improved with either overlays or underlays is reported as potential proof-tested standard solutions. The assessment procedure is demonstrated by providing a mock worked ex le of a detailed diaphragm assessment.

Manufacturing ultra-high performance concrete utilising conventional materials and production methods

Publisher: Elsevier BV

Date: 05-2016

DOI: 10.1016/J.CONBUILDMAT.2016.02.102

Seismic fragility assessment of nonstructural components in unreinforced clay brick masonry buildings

Publisher: Wiley

Date: 16-12-2020

DOI: 10.1002/EQE.3238

Digital image correlation (DIC) for measurement of strains and displacements in coarse, low volume-fraction FRP composites used in civil infrastructure

Publisher: Elsevier BV

Date: 03-2019

DOI: 10.1016/J.COMPSTRUCT.2019.01.024

Seismic assessment of out-of-plane loaded unreinforced masonry walls in multi-storey buildings

Publisher: New Zealand Society for Earthquake Engineering

Date: 30-06-2014

DOI: 10.5459/BNZSEE.47.2.119-138

Abstract: A procedure is proposed to evaluate the dynamic out-of-plane stability of cracked unreinforced masonry (URM) walls located in multi-storey URM buildings. The equations of dynamic motion are derived from first principles and representative single-degree-of-freedom (SDOF) models are proposed. The models have nonlinear stiffness properties that correspond to the restoring gravitational forces. A method is suggested to transform the nonlinear problem to a corresponding linear equivalent so that conventional spectral methods can be used to calculate wall response. The dynamic interaction between the URM building as the main structural system and the out-of-plane loaded walls as secondary elements is addressed by developing floor response spectra. Several buildings were assumed in a parametric study and subjected to code-compatible ground motion records. The absolute acceleration response at floor levels was calculated and the response spectra for that modified acceleration were subsequently obtained. The results from the study suggest that modifications should be made to the equations proposed for the Parts response spectra in the New Zealand seismic loading standard, NZS 1170.5:2004, in order to calculate the spectral response of out-of-plane loaded URM walls. Several worked ex les are presented to demonstrate application of the procedure.

Performance of masonry buildings and churches in the 22 February 2011 Christchurch earthquake

Publisher: New Zealand Society for Earthquake Engineering

Date: 31-12-2011

DOI: 10.5459/BNZSEE.44.4.279-296

Abstract: As part of the ‘Project Masonry’ Recovery Project funded by the New Zealand Natural Hazards Research Platform, commencing in March 2011, an international team of researchers was deployed to document and interpret the observed earthquake damage to masonry buildings and to churches as a result of the 22nd February 2011 Christchurch earthquake. The study focused on investigating commonly encountered failure patterns and collapse mechanisms. A brief summary of activities undertaken is presented, detailing the observations that were made on the performance of and the deficiencies that contributed to the damage to approximately 650 inspected unreinforced clay brick masonry (URM) buildings, to 90 unreinforced stone masonry buildings, to 342 reinforced concrete masonry (RCM) buildings, to 112 churches in the Canterbury region, and to just under 1100 residential dwellings having external masonry veneer cladding. In addition, details are provided of retrofit techniques that were implemented within relevant Christchurch URM buildings prior to the 22nd February earthquake and brief suggestions are provided regarding appropriate seismic retrofit and remediation techniques for stone masonry buildings.

The Mw 6.3 Abruzzo (Italy) earthquake of April 6th, 2009

Publisher: New Zealand Society for Earthquake Engineering

Date: 31-12-2009

DOI: 10.5459/BNZSEE.42.4.302-307

Abstract: On April 6th, 2009, at 3:32 am local time, a Mw 6.3 earthquake struck the Abruzzo region in Italy. This earthquake killed 305 people, with a further 1,500 people injured and approximately 15,000 buildings damaged. Many buildings of significant historical and architectural value were destroyed and several modern buildings were also severely damaged with some having fully collapsed. The authors visited the disaster zone one month after the earthquake. The most badly affected areas in L’Aquila historical centre and three other villages – San Gregorio, Pagánica and Onna – were inspected. The main observations made during this reconnaissance trip are briefly presented, highlighting the relevant lessons for engineering practice in New Zealand and Australia.

Australian earthquake engineering

Publisher: New Zealand Society for Earthquake Engineering

Date: 30-06-2003

DOI: 10.5459/BNZSEE.36.2.117-124

Abstract: The Australian Earthquake Engineering Society was established in 1990 with its main objective to promote and advance the practice of earthquake engineering and engineering seismology in Australia. In the decade or so since its establishment the Society has had some successes in this regard as well as some disappointments. In this paper, the author will highlight these along with research and other important professional developments during this period. The perceived obstacles to getting a better take-up of earthquake engineering amongst Australian practitioners and the role of the Society in furthering the cause of earthquake engineering in Australia will then be discussed. The paper will conclude with an outline of possible strategies for overcoming these obstacles.

Geometric characterisation and out-of-plane seismic stability of low-rise unreinforced brick masonry buildings in Auckland, New Zealand

Publisher: New Zealand Society for Earthquake Engineering

Date: 30-06-2014

DOI: 10.5459/BNZSEE.47.2.139-156

Abstract: The 2010-2011 Canterbury earthquakes and corresponding Royal Commission reports have resulted in changes to the legislative environment and led to increased public awareness in New Zealand of the earthquake performance of unreinforced masonry (URM) buildings. As a result, building regulators, owners, tenants, users and heritage stakeholders will be facing a unique challenge in the near future where assessments, improvements and demolitions of URM buildings are expected to occur at an unusually high rate. Auckland is the largest city in New Zealand and because of the relative prosperity of Auckland during the period 1880-1935 when most URM buildings were being constructed in New Zealand, the city has the largest number of URM buildings in the country. Identifying those buildings most at seismic risk in Auckland’s large and varied building stock has warranted a rapid field assessment program supplemented by strategically chosen detailed assessments. Information that can be procured through rapid field inspections includes the building geometric typologies (e.g., heights, building footprint geometry and isolated versus row configuration), elevation type (e.g., perforated frame versus solid wall), wall construction (e.g., solid versus cavity, number of leaves) and basic construction material type (e.g., clay brick versus stone). Furthermore, investigation into the architectural history, heritage status and functional usage of Auckland’s URM buildings will affect the direction of retrofit strategies and priorities. As the owner of a large and varied portfolio of URM buildings as well as the local organisation responsible for assessing building safety, Auckland Council is developing exemplar inspection, assessment, prioritisation and retrofit strategies that will target the seismic risks associated with URM buildings, in particular, so as to preserve and enhance safety and the economic and community value of these special buildings. Collaboration amongst Auckland Council, The University of Auckland and GNS Science has resulted in a state-of-the-art rapid quantitative assessment program applied to a s ling of typologically representative URM buildings in Auckland.

Estimating bedrock depth in the case of regolith sites using ambient noise analysis

Publisher: Elsevier BV

Date: 09-2018

DOI: 10.1016/J.ENGGEO.2018.06.022

Strategies for reducing heating and cooling loads of uninsulated rammed earth wall houses

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.ENBUILD.2014.03.031

University Of California, Berkeley

Location: United States of America

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University Of Adelaide

Location: Australia

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Linkage - International - Grant ID: LX0560474

Start Date: 03-2005

End Date: 12-2008

Amount: $52,450.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR0354894

Start Date: 02-2004

End Date: 06-2005

Amount: $10,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP160102070

Start Date: 04-2016

End Date: 12-2020

Amount: $380,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0985828

Start Date: 2009

End Date: 12-2014

Amount: $400,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0879592

Start Date: 2008

End Date: 12-2010

Amount: $435,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0556181

Start Date: 2005

End Date: 12-2009

Amount: $268,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP190100797

Start Date: 03-2019

End Date: 06-2023

Amount: $320,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP120100848

Start Date: 2012

End Date: 12-2016

Amount: $320,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0450933

Start Date: 2004

End Date: 12-2006

Amount: $185,734.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP140102695

Start Date: 2014

End Date: 07-2018

Amount: $241,130.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP220103665

Start Date: 11-2022

End Date: 11-2025

Amount: $308,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0349048

Start Date: 09-2003

End Date: 09-2006

Amount: $257,000.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR0354781

Start Date: 01-2004

End Date: 12-2003

Amount: $40,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE110100052

Start Date: 07-2011

End Date: 2015

Amount: $870,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE150100094

Start Date: 06-2015

End Date: 12-2018

Amount: $400,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE130100089

Start Date: 2013

End Date: 07-2014

Amount: $500,000.00

Funder: Australian Research Council