Seismic evaluation of unreinforced masonry buildings — a state-of-the-art report

1994 ◽  
Vol 21 (3) ◽  
pp. 512-539 ◽  
Author(s):  
Michel Bruneau
Keyword(s):  
State Of The Art ◽  
Unreinforced Masonry ◽  
Theoretical Background ◽  
Analytical Models ◽  
Specific Method ◽  
Masonry Buildings ◽  
Seismic Evaluation ◽  
Seismic Behaviour ◽  
Practical Applications ◽  
Research Activities

The potential vulnerability of old unreinforced masonry buildings, designed with little or no consideration for seismic-design requirements, is well documented. In regions without seismic retrofit ordinances prescribing a specific method to evaluate existing unreinforced masonry buildings, engineers have generally resorted to either conservative methods or various advanced analytical models. Although some approaches have received broader acceptance than others, there is still no consensus among practising engineers in North America. To provide perspective on the spectrum of strategies available and a clear overview of the state-of-the-art on this topic, this paper (i) presents the theoretical background and practical applications of a new procedure to evaluate unreinforced masonry bearing wall buildings, developed in California and recently integrated into the new Canadian Guidelines for the Seismic Evaluation of Existing Buildings, and (ii) summarizes the findings from other recent experimental and analytical research activities on the seismic behaviour of unreinforced masonry buildings, and from advances in their modelling. Key words: unreinforced masonry, masonry, earthquake, seismic response, state-of-the-art, evaluation, rehabilitation, analysis, models, buildings.

scholarly journals Simplified Seismic Assessment of Unreinforced Masonry Residential Buildings in the Balkans: The Case of Serbia

Buildings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 392
Author(s):  
Predrag Blagojević ◽  
Svetlana Brzev ◽  
Radovan Cvetković
Keyword(s):  
Seismic Design ◽  
Residential Buildings ◽  
Unreinforced Masonry ◽  
Seismic Assessment ◽  
Eurocode 8 ◽  
Masonry Buildings ◽  
Seismic Evaluation ◽  
Wall Area ◽  
The Balkans ◽  
Minimum Requirements

The paper presents a study on the existing low-rise unreinforced masonry (URM) buildings constructed in the period from 1945 to 1980 in Serbia and neighbouring countries in the Balkans. Buildings of this typology experienced damage in a few earthquakes in the region, including the 2010 Kraljevo, Serbia earthquake and the 2020 Petrinja, Croatia earthquake. The focus of the study is a seismic design approach for Simple masonry buildings according to Eurocode 8, Part 1, which is based on the minimum requirements for the total wall area relative to the floor plan area, which is referred to as Wall Index (WI) in this paper. Although the intention of Eurocode 8 is to use WI for design of new buildings, the authors believe that it could be also used for seismic assessment of existing masonry buildings in pre- and post-earthquake situations. A study on 23 URM buildings damaged in the 2010 Kraljevo, Serbia earthquake has been presented to examine a relationship between the WI and the extent of earthquake damage. Seismic evaluation of a typical 3-storey URM building damaged in the 2010 earthquake was performed according to the requirements of seismic design codes from the former Yugoslavia and Eurocode 8.

scholarly journals Numerical Simulation of Unreinforced Masonry Buildings with Timber Diaphragms

Buildings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 205
Author(s):  
Igor Tomić ◽  
Francesco Vanin ◽  
Ivana Božulić ◽  
Katrin Beyer
Keyword(s):  
Failure Modes ◽  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Masonry Buildings ◽  
Seismic Behaviour ◽  
Plane Failure ◽  
Friction Resistance ◽  
Flexible Diaphragms ◽  
Out Of Plane ◽  
Equivalent Frame

Though flexible diaphragms play a role in the seismic behaviour of unreinforced masonry buildings, the effect of the connections between floors and walls is rarely discussed or explicitly modelled when simulating the response of such buildings. These flexible diaphragms are most commonly timber floors made of planks and beams, which are supported on recesses in the masonry walls and can slide when the friction resistance is reached. Using equivalent frame models, we capture the effects of both the diaphragm stiffness and the finite strength of wall-to-diaphragm connections on the seismic behaviour of unreinforced masonry buildings. To do this, we use a newly developed macro-element able to simulate both in-plane and out-of-plane behaviour of the masonry walls and non-linear springs to simulate wall-to-wall and wall-to-diaphragm connections. As an unretrofitted case study, we model a building on a shake table, which developed large in-plane and out-of-plane displacements. We then simulate three retrofit interventions: Retrofitted diaphragms, connections, and diaphragms and connections. We show that strengthening the diaphragm alone is ineffective when the friction capacity of the wall-to-diaphragm connection is exceeded. This also means that modelling an unstrengthened wall-to-diaphragm connection as having infinite stiffness and strength leads to unrealistic box-type behaviour. This is particularly important if the equivalent frame model should capture both global in-plane and local out-of-plane failure modes.

Performance of masonry structures during the 1994 Northridge (Los Angeles) earthquake

1995 ◽  
Vol 22 (2) ◽  
pp. 378-402 ◽  
Author(s):  
Michel Bruneau
Keyword(s):  
Los Angeles ◽  
Unreinforced Masonry ◽  
Masonry Building ◽  
Masonry Buildings ◽  
Masonry Structures ◽  
Northridge Earthquake ◽  
Seismic Evaluation ◽  
Masonry Construction ◽  
Reinforced Masonry ◽  
The Impact

The surface magnitude 6.8 Northridge earthquake which struck the Los Angeles area on January 17, 1994, damaged a large number of engineered buildings, of nearly all construction types. As earthquakes of at least similar strength are expected to occur in most of eastern and western Canada, the study of the effects of this earthquake is of particular significance to Canada. This paper, as part of a concerted multi-paper reporting effort, concentrates on the damage suffered by masonry buildings during this earthquake, and explains why the various types of observed failures occurred. The seismic performance of all masonry construction similar to that commonly found in Canada is reviewed, but a particular emphasis is placed on providing an overview of damage to unreinforced masonry structures which had been rehabilitated before this earthquake. To provide a better appreciation of the impact of this earthquake on masonry buildings, and a better assessment of the engineering significance of their damage in a Canadian perspective, this paper first reviews the evolution of building code requirements for unreinforced masonry buildings up to the seismic retrofit ordinances enacted prior to this earthquake. Examples of various damage types, as observed by the author during his reconnaissance visit to the stricken area, are then presented, along with technically substantiated descriptions of the causes for this damage, and cross-references to relevant clauses from Canadian standards and codes, as well as the recently published Canadian Guidelines for the Seismic Evaluation of Existing Buildings, whenever appropriate. Key words: earthquake, unreinforced masonry, seismic rehabilitation, retrofit, retrofitted masonry building, reinforced masonry, buildings, failure, collapse, heritage buildings.

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