An experimental and numerical contribution for understanding the in-situ shear behaviour of unreinforced masonry

2021 ◽  
pp. 103389
Author(s):  
Pratik N. Gajjar ◽  
Elena Gabrielli ◽  
Dafne Carolina Martin-Alarcon ◽  
João M. Pereira ◽  
Paulo B. Lourenço ◽  
...  
Keyword(s):  
Unreinforced Masonry ◽  
Shear Behaviour

A laboratory fracture shear cell used for simulation of fracture reactivation

2011 ◽  
Vol 51 (1) ◽  
pp. 487 ◽  
Author(s):  
Mohammad Sadegh Asadi ◽  
Vamegh Rasouli
Keyword(s):  
Significant Influence ◽  
Fault Reactivation ◽  
Shear Behaviour ◽  
Rock Fractures ◽  
Normal Stresses ◽  
Shear Tests ◽  
Shear Cell ◽  
In Situ Stresses ◽  
Wide Range

Fault reactivation is an unfavourable incident during drilling and production that may occur due to changes in situ stresses and reservoir pressure. Only a few studies, in their analyses, have included the effects of fault geometrical properties—these are important parameters controlling fault slippage and damage around it. In this paper, the significant influence of fracture morphology on the mechanical behaviour of rock fractures was investigated through experimental studies of shearing rock fractures in the lab. The experiments carried out using a fracture shear cell (FSC): the cell that was modified by adding a number of components to an existing true triaxial stress cell (TTSC) and designing a duplex high pressure cylinder that is capable of applying large normal stresses to the sample at a constant rate. A number of artificial blocks made of mortar material were subjected to shear tests using FSC under a wide range of normal stresses and at different shearing directions. The outputs of uniaxial compressive strength and fracture shear tests in the lab were used to plot the failure envelope of the fractured rock mass and discuss the failure mechanism through shearing. Accordingly, a calibrated, numerical discrete element method (DEM) was used to simulate the shear behaviour of fractures previously tested in the lab. The results of lab tests and DEM simulations will be presented and different failure mechanisms that are expected during shearing will be explained. The results show the significant influence of surface roughness on shear strength and extent of damage zone along the fracture. It was found that the shearing response of fractures depends on the magnitude of normal stress, which indicates the importance of having a good knowledge of in-situ stresses when modelling fault reactivation and damage near the fault zones. The results of lab experiments and numerical simulations were compared and good agreements were observed.

Damage Reconnaissance of Unreinforced Masonry Bearing Wall Buildings after the 2015 Gorkha, Nepal, Earthquake

2017 ◽  
Vol 33 (1_suppl) ◽  
pp. 243-273 ◽  
Author(s):  
Giuseppe Brando ◽  
Davide Rapone ◽  
Enrico Spacone ◽  
Matt S. O'Banion ◽  
Michael J. Olsen ◽  
...  
Keyword(s):  
Response Spectra ◽  
Visual Assessment ◽  
Unreinforced Masonry ◽  
Assessment Process ◽  
Gorkha Earthquake ◽  
Field Reconnaissance ◽  
2015 Gorkha Earthquake ◽  
Out Of Plane ◽  
2015 Gorkha Nepal Earthquake

This paper documents and analyzes the seismic behavior of unreinforced masonry (URM) buildings that were damaged by the 2015 Gorkha earthquake in Nepal, and reports on the performance of palaces, giving an overview on the failures suffered by significant examples of these monumental buildings. Field reconnaissance was completed through both rapid, in-situ visual assessment and state-of-the-art procedures utilizing light detection and ranging (lidar) and virtual reality (VR) technologies. Both the visual and virtual assessments were compared for 20 structures and were generally consistent; however, the virtual assessment process enabled detection of damage that could not be captured or was difficult to distinguish in the field observations. Further, both in-plane and out-of-plane mechanisms were analyzed and attributed to specific structural deficiencies that usually characterize poorly detailed masonry buildings. Moreover, wall overturning was correlated with the peculiarities of the pseudo-accelerations and rocking response spectra of the earthquake.

Material properties of existing unreinforced clay brick masonry buildings in New Zealand

2014 ◽  
Vol 47 (2) ◽  
pp. 75-96 ◽  
Author(s):  
Nasser Almesfer ◽  
Dmytro Y. Dizhur ◽  
Ronald Lumantarna ◽  
Jason M. Ingham
Keyword(s):  
New Zealand ◽  
Material Properties ◽  
Research Programme ◽  
Unreinforced Masonry ◽  
Clay Brick ◽  
In Situ Testing ◽  
Brick And Mortar ◽  
Masonry Material ◽  
Assessment Guidelines

The material properties of New Zealand’s heritage clay brick unreinforced masonry (URM) buildings were investigated and are reported herein. Material data was collected from a total of 98 New Zealand clay brick URM buildings and a database was compiled that was comprised of various masonry material properties. The intention behind the reporting of information and data presented herein was to provide indicative values to the professional engineering community to aid as preliminary input when undertaking detailed building assessments for cases where in-situ testing and brick and mortar sample extraction are not feasible. The data presented is also used to support the relationships for URM material properties that have been recommended by the authors for incorporation into the next version of the NZSEE seismic assessment guidelines for URM buildings. Although researchers from Europe, USA, India and Australia have previously studied the material properties of clay brick unreinforced masonry, knowledge on New Zealand URM material properties was poor at the time the study commenced. Therefore, a research programme was undertaken that was focused on both in-situ testing and laboratory testing of samples extracted from existing New Zealand clay brick URM buildings.

scholarly journals Effect of Moisture Content on the Shear Behaviour of a Completely Decomposed Granite: An Experimental Study

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Pan Liu ◽  
Jinhong Lin ◽  
Yang Wang ◽  
Xueqiang Yang
Keyword(s):  
Moisture Content ◽  
Linear Equations ◽  
Safety Evaluation ◽  
Shear Behaviour ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Decomposed Granite ◽  
Effect Of Moisture ◽  
Completely Decomposed Granite

To figure out the effect of moisture content on the shear behaviour of undisturbed completely decomposed granite (CDG) soil, a series of in situ and laboratory direct shear tests were carried out, under different normal stress and moisture contents. The test results showed that the increasing moisture content could obviously weaken the shear strength, cohesion, and frictional angle. Two linear equations were proposed for estimating the cohesion and the frictional angle at any moisture content in the field. The estimated strength parameters could be used for safety evaluation and/or engineering design of CDG cutting slope. The rate of reduction of the cohesion was much higher than that of the tangent value of frictional angle. Due to the disturbance of laboratory sample and size effect, the strength parameters obtained from the in situ test were a little bit higher than those from the laboratory test.

scholarly journals In Situ Out-of-Plane Testing of Unreinforced Masonry Cavity Walls in as-Built and Improved Conditions

Structures ◽  
2015 ◽  
Vol 3 ◽  
pp. 187-199 ◽  
Author(s):  
Kevin Q. Walsh ◽  
Dmytro Y. Dizhur ◽  
Jalil Shafaei ◽  
Hossein Derakhshan ◽  
Jason M. Ingham
Keyword(s):  
Unreinforced Masonry ◽  
Out Of Plane

Diagonal shear behaviour of unreinforced masonry wallettes strengthened using twisted steel bars

2011 ◽  
Vol 25 (12) ◽  
pp. 4386-4393 ◽  
Author(s):  
Najif Ismail ◽  
Robert B. Petersen ◽  
Mark J. Masia ◽  
Jason M. Ingham
Keyword(s):  
Unreinforced Masonry ◽  
Shear Behaviour ◽  
Steel Bars

Failure of wall–slab joint in unreinforced masonry building

2016 ◽  
Vol 20 (5) ◽  
pp. 759-771 ◽  
Author(s):  
Feng Lin ◽  
Xiuming Yang ◽  
Keyu Li ◽  
Xianglin Gu ◽  
Xiang Li
Keyword(s):  
Progressive Collapse ◽  
Precast Concrete ◽  
Unreinforced Masonry ◽  
Masonry Building ◽  
Masonry Buildings ◽  
Continuous Cast ◽  
Concrete Floor ◽  
Simply Supported ◽  
Floor Slabs

Investigations on buildings severely damaged due to earthquakes or explosions have indicated that unreinforced masonry buildings with simply supported precast concrete floor slabs exhibit deficiencies in resistance to progressive collapse, compared to unreinforced masonry buildings with continuous cast in situ concrete floor slabs. The collapse mechanisms observed in the two types of unreinforced masonry buildings are closely related to wall–slab joint failure. The purpose of this study is to investigate the failure behavior of wall–slab joints and the effect on the collapse of the two types of unreinforced masonry buildings. Six wall–slab joint specimens and eight grooved wall specimens, induced by partial failure of wall–slab joints, were tested under monotonic vertical and horizontal loading. Numerical models were then developed, verified, and used to perform a parametric study. It was found that the wall–slab joints failed in various modes, that is, slab failure, wall failure, and slab pullout failure. The grooved wall could fail in bending or in compression. Analyses indicated that the collapse of unreinforced masonry buildings with simply supported precast concrete floor slabs develops in both vertical and horizontal directions. However, the collapse of unreinforced masonry buildings with continuous cast in situ concrete floor slabs is prone to develop only in the vertical direction, resulting in improved progressive collapse resistance.

The Diagnosis Research Project

1994 ◽  
Vol 10 (1) ◽  
pp. 151-170 ◽  
Author(s):  
Luigia Binda ◽  
Giulio Mirabella Roberti ◽  
Silvia Abbaneo
Keyword(s):  
Structural Analysis ◽  
Damage Assessment ◽  
Laboratory Tests ◽  
Input Data ◽  
Unreinforced Masonry ◽  
Masonry Structures ◽  
Research Project ◽  
Seismic Rehabilitation ◽  
And Control

The Friuli and Irpinia earthquakes, and subsequent experiences, have underscored the need for adequate damage assessment prior to seismic rehabilitation. Furthermore, assessment can be enhanced by preventive studies under the guidance of those in charge of hazard mitigation (architects, engineers, etc.). Research procedures must be defined so that findings can be used for damage assessment and as input data for structural analysis and control models. This paper provides evaluations of in-situ and laboratory tests on materials for existing unreinforced masonry structures and, in particular, touches upon the difficulty of interpreting the results of NDE tests. Furthermore the need for a design of the investigation prepared by persons responsible for the rehabilitation is pointed out.

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