scholarly journals Seismic Behaviour of Strengthened Unreinforced Masonry Walls using Kevlar-FRP

2021 ◽  
Vol 23 (1) ◽  
pp. 44-53
Author(s):  
Sugeng Wijanto ◽  
Takim Andriono ◽  
Jovita Augusta Tanudjaja
Keyword(s):  
Three Dimensional ◽  
Fiber Material ◽  
High Strength ◽  
Unreinforced Masonry ◽  
Inertia Force ◽  
Masonry Walls ◽  
Seismic Behaviour ◽  
Laboratory Test Results ◽  
Computer Analyses ◽  
High Strength Fiber

Unreinforced masonry walls (URM) in old buildings are vulnerable to collapse upon receiving high lateral inertia force due to earthquakes. However, a high strength fiber material such as Kevlar fiber has been identified as able to improve the URM-Wall performance, especially in shear strength enhancement. In this research, the seismic performance of an URM-Wall was analysed using SAP2000 by modeling the wall with three dimensional solid elements. Solids and springs as link connectors were assigned to represent the masonry behavior. The aim of this research is to compare between results obtained from the computer analyses and the previously conducted laboratory experiments. The effectiveness of Kevlar material installed in the diagonal directions of both wall surfaces was investigated. It was found that the failure mechanism shown by the SAP2000 model is similar to the laboratory test results.

scholarly journals A Study on Finite Element Modelling and Analysis with respect to Experimental Results of Strengthened Unreinforced Masonry Walls With and Without Kevlar-FRP

2021 ◽  
Vol 23 (2) ◽  
pp. 67-77
Author(s):  
Sugeng Wijanto ◽  
Takim Andriono ◽  
Jovita Tanudjaja
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Three Dimensional ◽  
Unreinforced Masonry ◽  
Shear Capacity ◽  
Masonry Walls ◽  
Test Results ◽  
Element Modelling ◽  
Laboratory Test Results ◽  
Set Up

Unreinforced masonry (URM) walls, found in most historical buildings in Indonesia, are relatively brittle with wide variety of material properties. The behaviour of URM walls is very complex, especially when subjected to seismic excitation. In this research, a finite element modelling was set up in order to analyse the seismic performance of URM wall experimental test units, with and without strengthening material. The analysis was conducted using SAP2000 computer program. Three dimensional solids and springs as link connectors were assigned to represent the masonry behaviour. This research aims to compare results obtained from the computer analysis and the previously conducted laboratory experiments. The effectiveness of Kevlar fibre material, which was installed on both wall surfaces and modelled as truss element was also investigated. It was found that the failure mechanisms shown by the SAP2000 model was similar to the laboratory test results. The use of Kevlar Fibre as strengthening material was found able to significantly increase the stiffness and shear capacity of the URM wall.

scholarly journals Seismic behaviour of unreinforced masonry walls

1985 ◽  
Vol 18 (2) ◽  
pp. 191-205 ◽  
Author(s):  
M. J. N. Priestley
Keyword(s):  
Seismic Performance ◽  
Elastic Stress ◽  
Seismic Loading ◽  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Assessment Procedure ◽  
Seismic Behaviour ◽  
Traditional Methods ◽  
Load Response

The behaviour of unreinforced masonry walls under seismic loading is considered, with particular emphasis being given to face-load response. It is shown that traditional methods of assessing seismic performance based on elastic stress calculations result in excessively conservative results when compared with more realistic methods of assessment. In particular, an assessment procedure based on energy considerations is developed at some length, and is illustrated by a worked sample.

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.

scholarly journals Seismic behaviour of unreinforced masonry walls

1986 ◽  
Vol 19 (1) ◽  
pp. 65-75 ◽  
Author(s):  
L. M. Robinson ◽  
M. J. N. Priestley
Keyword(s):  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Seismic Behaviour

COMPARITIVE STUDY ON HIGH STRENGTH FIBER REINFORCED SELF CURING SCC AND CONVENTIONAL CURED SCC

2016 ◽  
Vol 5 (2) ◽  
pp. 32
Author(s):  
LOHITHA V ◽  
KRISHNESWAR R ◽  
KUMAR B. NARENDRA ◽  
◽  
◽  
...  
Keyword(s):  
High Strength ◽  
Fiber Reinforced ◽  
High Strength Fiber

scholarly journals Compressive behaviours of octet-truss lattices

2020 ◽  
Vol 234 (16) ◽  
pp. 3257-3269 ◽  
Author(s):  
Yifan Li ◽  
Huaiyuan Gu ◽  
Martyn Pavier ◽  
Harry Coules
Keyword(s):  
Failure Modes ◽  
Density Ratio ◽  
Three Dimensional ◽  
Compressive Load ◽  
High Strength ◽  
Detailed Comparison ◽  
Compressive Response ◽  
Beam Elements ◽  
Structural Applications ◽  
Octet Truss

Octet-truss lattice structures can be used for lightweight structural applications due to their high strength-to-density ratio. In this research, octet-truss lattice specimens were fabricated by stereolithography additive manufacturing with a photopolymer resin. The mechanical properties of this structure have been examined in three orthogonal orientations under the compressive load. Detailed comparison and description were carried out on deformation mechanisms and failure modes in different lattice orientations. Finite element models using both beam elements and three-dimensional solid elements were used to simulate the compressive response of this structure. Both the load reaction and collapse modes obtained in simulations were compared with test results. Our results indicate that three-dimensional continuum element models are required to accurately capture the behaviour of real trusses, taking into account the effects of finite-sized beams and joints.

scholarly journals Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
High Strength ◽  
Element Model ◽  
Internal Force ◽  
Foundation Pit ◽  
Dimensional Finite Element ◽  
Influence Of Temperature On ◽  
Scale Experiment ◽  
Three Dimensional Finite Element

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

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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