Limit State Strength of Unreinforced Masonry Structures

2013 ◽  
Vol 29 (1) ◽  
pp. 1-31 ◽  
Author(s):  
A. H. Akhaveissy
Keyword(s):  
Limit State ◽  
Lateral Force ◽  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Masonry Structures ◽  
Interface Model ◽  
Numerical Predictions ◽  
State Strength ◽  
New Formula ◽  
Error Percentage

This paper presents a new formula to estimate the ultimate lateral force of unreinforced masonry structures. The ratio of the wall's height to the wall's width is used to predict the ultimate lateral load of the wall. The coefficient is determined by the numerical implementation of an interface model to simulate the behavior of mortar joints in masonry walls. The numerical predictions are compared with the FEMA guidelines and the experimental data. The comparisons show that the loads that are predicted by the proposed formula have a lower error percentage than the FEMA guidelines. Thus, the proposed formula can be used to analyze unreinforced masonry structures.

scholarly journals Evaluation of the Performance of Unreinforced Stone Masonry Greek “Basilica” Churches When Subjected to Seismic Forces and Foundation Settlement

Buildings ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 106 ◽  
Author(s):  
George C. Manos ◽  
Lambros Kotoulas ◽  
Evangelos Kozikopoulos
Keyword(s):  
Shear Failure ◽  
Limit State ◽  
Failure Criteria ◽  
Stone Masonry ◽  
Foundation Settlement ◽  
Masonry Structures ◽  
Long Term Effects ◽  
Structural Behaviour ◽  
Numerical Predictions ◽  
Numerical Process

Unreinforced stone masonry made of low strength mortar has been used for centuries in forming old type stone masonry churches of the “Basilica” typology. The seismic performance of such stone masonry structures damaged during recent strong seismic activity in Greece, combined with long term effects from foundation settlement, is presented and discussed. A simplified numerical process is presented for evaluating the performance of such damaged stone masonry structures, making use of linear and non-linear numerical tools and assumed limit-state failure criteria. In order to obtain a quantification of the in-plane sliding shear failure criterion, a number of stone masonry wallets were built with weak mortar and were tested in the laboratory. Through the comparison of the obtained numerical predictions with the observed structural behaviour for selected cases of stone masonry “Basilica” churches, the validity of the applied simplified numerical process is demonstrated. It is shown that reasonable approximation of the observed performance of such structures can be obtained when the assumed failure criteria are realistic.

Nonlinear Finite Element Analysis of Unreinforced Masonry Walls

2016 ◽  
Vol 857 ◽  
pp. 142-147
Author(s):  
S. Thomas Feba ◽  
Bennet Kuriakose
Keyword(s):  
Numerical Model ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Seismic Retrofitting ◽  
Nonlinear Static Analysis ◽  
Masonry Walls ◽  
Masonry Structures ◽  
Element Analysis ◽  
Historical Masonry ◽  
Nonlinear Static

Most of the monumental structures worldwide and residential structures in developing countries are built in masonry. The studies performed by various researchers prove the vulnerability of masonry structures under various circumstances, especially under earthquakes, so as to necessitate detailed contemplation. In this paper, a numerical model for nonlinear static analysis of unreinforced masonry walls is developed based on a macro-modelling approach. A detailed parametric study is also performed to analyse the effect of wall thickness as well as length on the behaviour of the masonry wall. The present numerical model can be utilized for risk assessment and seismic retrofitting of historical masonry structures.

scholarly journals Effect of Aftershocks on Seismic Fragilities of Single-Story Masonry Structures

2021 ◽  
Vol 9 ◽  
Author(s):  
Hao Zhang ◽  
Tong Sun ◽  
Shi-Wei Hou ◽  
Qing-Meng Gao ◽  
Xi Li
Keyword(s):  
Seismic Response ◽  
Fragility Curves ◽  
Limit State ◽  
Unreinforced Masonry ◽  
Aftershock Sequence ◽  
Seismic Demand ◽  
Masonry Structures ◽  
Confined Masonry ◽  
Demand Models ◽  
Probabilistic Seismic Demand

The effect of aftershocks on the fragility of single-story masonry structures is investigated using probabilistic seismic demand analysis Finite element models of an unreinforced masonry (URM) structure and a confined masonry (CM) structure are established and their seismic response characteristics when subjected to mainshock, aftershock, and the mainshock-aftershock sequence are then comparatively investigated. The effects of aftershocks and the use of confining members on the seismic response are studied. Probabilistic seismic demand models of the structures are built, and fragility curves under various conditions are derived to investigate the effect of aftershocks on structural fragility. The maximum roof displacement and maximum inter-story drift ratio are lower in the confined masonry model than in the unreinforced masonry model; additionally, the probability of exceedance (PE) values of each damage limit state reduced, and those of the mainshock-damaged models subjected to aftershock significantly increase compared to those directly subjected to a same-intensity aftershock. The probability of severe damage or collapse compared with the mainshock-damaged CM model is greater than when each is subjected to a same intensity aftershock. The use of confining members benefits aftershock resistance and reduces the failure probability of the mainshock-damaged structure. The PE values significantly increase with the aftershock scaling factor δ. Therefore, the effect of aftershocks should be considered in the seismic design and analysis of masonry structures.

scholarly journals The DSC Model for the Nonlinear Analysis of In-plane Loaded Masonry Structures

2012 ◽  
Vol 6 (1) ◽  
pp. 200-214 ◽  
Author(s):  
A. H. Akhaveissy
Keyword(s):  
Constitutive Relations ◽  
Unreinforced Masonry ◽  
Nonlinear Finite Element ◽  
Masonry Structures ◽  
Nonlinear Finite Element Method ◽  
Quadrilateral Elements ◽  
Numerical Predictions ◽  
Disturbed State Concept ◽  
Associative Behavior

A nonlinear finite element method with eight-noded isoparametric quadrilateral elements is used to predict the behavior of unreinforced masonry structures. The disturbed state concept (DSC) with modified hierarchical single yield surface (HISS) plasticity which is called DSC/HISS-CT is used to characterize the constitutive behavior of masonry in both compression and tension. The model uses two HISS yield surfaces for compressive and tensile behavior. The DSC model allows for the characterization of non-associative behavior through the use of disturbance. It computes microcrack-ing during deformation, which eventually leads to fracture and failure. the critical disturbance, Dc, identifies fracture and failure. In the DSC model the DSC model was validated at two levels: (1) specimen and (2) practical boundary value problem. At the specimen level, predictions are obtained by integrating the incremental constitutive relations. The pro-posed constitutive model is verified by comparing numerical predictions with results obtained from test data; the compari-sons are found to be highly satisfactory. A new explicit formula is also presented to estimate the strength of unreinforced masonry structures.

Assessing vibration induced damage in unreinforced masonry walls subject to vehicular impact – A numerical study

2021 ◽  
Vol 245 ◽  
pp. 112843
Author(s):  
Mohammad Asad ◽  
Tatheer Zahra ◽  
David P Thambiratnam ◽  
Tommy H.T. Chan ◽  
Yan Zhuge
Keyword(s):  
Numerical Study ◽  
Unreinforced Masonry ◽  
Masonry Walls

Full‐scale shake‐table tests on two unreinforced masonry cavity‐wall buildings: effect of an innovative timber retrofit

2021 ◽  
Author(s):  
Marco Miglietta ◽  
Nicolò Damiani ◽  
Gabriele Guerrini ◽  
Francesco Graziotti
Keyword(s):  
Seismic Vulnerability ◽  
Concrete Slab ◽  
Cost Effective ◽  
Unreinforced Masonry ◽  
Full Scale ◽  
Cavity Wall ◽  
Masonry Walls ◽  
Shake Table ◽  
Earthquake Excitation ◽  
Reinforced Concrete Slab

AbstractTwo full-scale building specimens were tested on the shake-table at the EUCENTRE Foundation laboratories in Pavia (Italy), to assess the effectiveness of an innovative timber retrofit solution, within a comprehensive research campaign on the seismic vulnerability of existing Dutch unreinforced masonry structures. The buildings represented the end-unit of a two-storey terraced house typical of the North-Eastern Netherlands, a region affected by induced seismicity over the last few decades. This building typology is particularly vulnerable to earthquake excitation due to lack of seismic details and irregular distribution of large openings in masonry walls. Both specimens were built with the same geometry. Their structural system consisted of cavity walls, with interior load-bearing calcium-silicate leaf and exterior clay veneer, and included a first-floor reinforced concrete slab, a second-floor timber framing, and a roof timber structure supported by masonry gables. A timber retrofit was designed and installed inside the second specimen, providing an innovative sustainable, light-weight, reversible, and cost-effective technique, which could be extensively applied to actual buildings. Timber frames were connected to the interior surface of the masonry walls and completed by oriented strands boards nailed to them. The second-floor timber diaphragm was stiffened and strengthened by a layer of oriented-strand boards, nailed to the existing joists and to additional blocking elements through the existing planks. These interventions resulted also in improved wall-to-diaphragm connections with the inner leaf at both floors, while steel ties were added between the cavity-wall leaves. The application of the retrofit system favored a global response of the building with increased lateral capacities of the masonry walls. This paper describes in detail the bare and retrofitted specimens, compares the experimental results obtained through similar incremental dynamic shake-table test protocols up to near-collapse conditions, and identifies damage states and damage limits associated with displacements and deformations.

scholarly journals Numerical Modeling of Unreinforced Masonry Walls Strengthened with Fe-Based Shape Memory Alloy Strips

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2961
Author(s):  
Moein Rezapour ◽  
Mehdi Ghassemieh ◽  
Masoud Motavalli ◽  
Moslem Shahverdi
Keyword(s):  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Vertical Strip ◽  
Maximum Resistance ◽  
The Cross ◽  
Post Tensioning

This study presents a new way to improve masonry wall behavior. Masonry structures comprise a significant part of the world’s structures. These structures are very vulnerable to earthquakes, and their performances need to be improved. One way to enhance the performances of such types of structures is the use of post-tensioning reinforcements. In the current study, the effects of shape memory alloy as post-tensioning reinforcements on originally unreinforced masonry walls were investigated using finite element simulations in Abaqus. The developed models were validated based on experimental results in the literature. Iron-based shape memory alloy strips were installed on masonry walls by three different configurations, namely in cross or vertical forms. Seven macroscopic masonry walls were modeled in Abaqus software and were subjected to cyclic loading protocol. Parameters such as stiffness, strength, durability, and energy dissipation of these models were then compared. According to the results, the Fe-based strips increased the strength, stiffness, and energy dissipation capacity. So that in the vertical-strip walls, the stiffness increases by 98.1%, and in the cross-strip model's position, the stiffness increases by 127.9%. In the vertical-strip model, the maximum resistance is equal to 108 kN, while in the end cycle, this number is reduced by almost half and reaches 40 kN, in the cross-strip model, the maximum resistance is equal to 104 kN, and in the final cycle, this number decreases by only 13.5% and reaches 90 kN. The scattering of Fe-based strips plays an important role in energy dissipation. Based on the observed behaviors, the greater the scattering, the higher the energy dissipation. The increase was more visible in the walls with the configuration of the crossed Fe-based strips.

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