Seismic fragility of regular masonry buildings for in-plane and out-of-plane failure

Seismic assessments of historical masonry buildings are affected by several sources of epistemic uncertainty. These are mainly the material and the modelling parameters and the displacement capacity of the elements. Additional sources of uncertainty lie in the non-linear connections, such as wall-to-wall and floor-to-wall connections. Latin Hypercube Sampling was performed to create 400 sets of 11 material and modelling parameters. The proposed approach is applied to historical stone masonry buildings with timber floors, which are modelled by an equivalent frame approach using a newly developed macroelement accounting for both in-plane and out-of-plane failure. Each building is modelled first with out-of-plane behaviour enabled and non-linear connections, and then with out-of-plane behaviour disabled and rigid connections. For each model and set of parameters, incremental dynamic analyses are performed until building failure and seismic fragility curves derived. The key material and modelling parameters influencing the performance of the buildings are determined based on the peak ground acceleration at failure, type of failure and failure location. This study finds that the predicted PGA at failure and the failure mode and location is as sensitive to the properties of the non-linear connections as to the material and displacement capacity parameters, indicating that analyses must account for this uncertainty to accurately assess the in-plane and out-of-plane failure modes of historical masonry buildings. It also shows that modelling the out-of-plane behaviour produces a significant impact on the seismic fragility curves.

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Local out-of-plane failure modes in traditional block-masonry buildings

Masonry Construction in Active Seismic Regions ◽

10.1016/b978-0-12-821087-1.00001-6 ◽

2021 ◽

pp. 289-322

Author(s):

Claudia Casapulla

Keyword(s):

Failure Modes ◽

Masonry Buildings ◽

Plane Failure ◽

Out Of Plane

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Effect of out-of-plane behavior on seismic fragility of masonry buildings in Turkey

Bulletin of Earthquake Engineering ◽

10.1007/s10518-013-9449-0 ◽

2013 ◽

Vol 11 (5) ◽

pp. 1775-1795 ◽

Cited By ~ 6

Author(s):

Hasan Burak Ceran ◽

Murat Altug Erberik

Keyword(s):

Seismic Fragility ◽

Masonry Buildings ◽

Out Of Plane

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Environmental and Economic Impact of Retrofitting Techniques to Prevent Out-of-Plane Failure Modes of Unreinforced Masonry Buildings

Sustainability ◽

10.3390/su132011383 ◽

2021 ◽

Vol 13 (20) ◽

pp. 11383

Author(s):

Linda Giresini ◽

Claudia Casapulla ◽

Pietro Croce

Keyword(s):

Environmental Impact ◽

Failure Modes ◽

Energy Savings ◽

Energy Performance ◽

Masonry Buildings ◽

Plane Failure ◽

Seismic Displacement ◽

Cost Curves ◽

Integrated Intervention ◽

Out Of Plane

This paper presents an innovative methodology to assess the economic and environmental impact of integrated interventions, namely solutions that improve both structural and energy performance of existing masonry buildings, preventing out-of-plane modes and increasing their energy efficiency. The procedure allows the assessment of the environmental and the economic normalized costs of each integrated intervention, considering seismic and energy-saving indicators. In addition, the work introduces in relative or absolute terms two original indicators, associated with seismic displacement and thermal transmittance. The iso-cost curves so derived are thus a powerful tool to compare alternative solutions, aiming to identify the most advantageous one. In fact, iso-cost curves can be used with a twofold objective: to determine the optimal integrated intervention associated with a given economic/environmental impact, or, as an alternative, to derive the pairs of seismic and energy performance indicators associated with a given budget. The analysis of a somehow relevant case study reveals that small energy savings could imply excessive environmental impacts, disproportionally increasing the carbon footprint characterizing each intervention. Iso-cost curves in terms of absolute indicators are more suitable for assessing the effects of varying acceleration demands on a given building, while iso-cost curves in terms of relative indicators are more readable to consider a plurality of cases, located in different sites. The promising results confirm the effectiveness of the proposed method, stimulating further studies.

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Numerical Simulation of Unreinforced Masonry Buildings with Timber Diaphragms

Buildings ◽

10.3390/buildings11050205 ◽

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.

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