Out-of-plane behavior of confined masonry walls with aspect ratios greater than one

2021 ◽  
Vol 48 (1) ◽  
pp. 89-97
Author(s):  
Jorge Varela-Rivera ◽  
Joel Moreno-Herrera ◽  
Luis Fernandez-Baqueiro ◽  
Juan Cacep-Rodriguez ◽  
Cesar Freyre-Pinto
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
Compressive Stress ◽  
Masonry Walls ◽  
Confined Masonry ◽  
Aspect Ratios ◽  
Out Of Plane ◽  
Axial Compressive Stress ◽  
Compressive Strut ◽  
Failure Line

An experimental study on the out-of-plane behavior of confined masonry walls is presented. Four confined walls with aspect ratios greater than one were tested in the laboratory. Walls were subjected to combined axial and out-of-plane uniform loads. The variables studied were the aspect ratio and the axial compressive stress of walls. It was observed that the out-of-plane strength of walls increased as the aspect ratio or the axial compressive stress increased. Failure of walls was associated with crushing of masonry. Analytical out-of-plane strength of walls was determined using the yielding line, failure line, modified yielding line, compressive strut and bidirectional strut methods. It was concluded that the experimental out-of-plane strength of walls was best predicted with the bidirectional strut method.

scholarly journals Deviatoric Stress Evolution Laws and Control in Surrounding Rock of Soft Coal and Soft Roof Roadway under Intense Mining Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Dongdong Chen ◽  
Chunwei Ji ◽  
Shengrong Xie ◽  
En Wang ◽  
Fulian He ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Plastic Zone ◽  
Theoretical Calculations ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Deviatoric Stress ◽  
Anchor Cable ◽  
Soft Coal ◽  
Working Face ◽  
Failure Line

Aiming at the problem of large deformation and instability failure and its control of soft coal and soft roof roadway under intense mining, laboratory experiments, theoretical calculations, Flac3D numerical simulation, borehole peeping, and pressure observation were used to study the deflection characteristics of the deviatoric stress of the gas tailgate and the distribution and failure characteristics of the plastic zone in the mining face considering the strain softening characteristics of the roof and coal of roadway, and then the truss anchor cable-control technology is proposed. The results show the following: (1) The intense mining influence on the working face will deflect the peak deviatoric stress zone (PDSZ) of the surrounding rock of the gas tailgate. The influence distance of PDSZ is about 20 m in advance and 60 m in lag; the PDSZ at the gob side of the roadway is located in the range of 3–5.5 m from the surface of the coal pillar, while the coal wall side is mainly located in the range of 3–4.5 m at the shoulder corner and bottom corner of the solid coal. (2) The intense mining in the working face caused the nonuniform expansion of the surrounding rock plastic area of the gas tailgate. The two shoulder angles of the roadway and the bottom of the coal pillar have the largest damage range, and the maximum damage location is the side angle of the coal pillar (5 m). Angle and bottom angle of coal pillar are the key points of support control. (3) The plastic failure line of the surrounding rock of the gas tailgate is always between the inner and outer contours of the PDSZ, and the rock mass in the PDSZ is in a stable and unstable transition state, so the range of anchor cable support should be cross plastic failure line. (4) The theoretical calculations and numerical simulation results agree well with the drilling peep results. Based on the deflection law of the PDSZ and the expansion characteristics of the plastic zone, a truss anchor cable supporting system with integrated locking and large-scale support function is proposed to jointly control the roof and the two sides, which effectively solves the problem of weak surrounding rock roadway under severe mining deformation control problems realizing safety and efficient production in coal mines under intense mining.

Modified state parameter for characterizing static liquefaction of sand with fines

2009 ◽  
Vol 46 (3) ◽  
pp. 281-295 ◽  
Author(s):  
D. C. Bobei ◽  
S. R. Lo ◽  
D. Wanatowski ◽  
C. T. Gnanendran ◽  
M. M. Rahman
Keyword(s):  
Critical State ◽  
Volumetric Strain ◽  
State Parameter ◽  
Confining Pressure ◽  
Log P ◽  
Test Results ◽  
Static Liquefaction ◽  
Isotropic Consolidation ◽  
Failure Line ◽  
Soil Behaviour

An experimental study was carried out to investigate the static liquefaction behaviour of sand with a small amount of plastic and nonplastic fines. Five series of tests were conducted in drained and undrained conditions. The drained test results indicate not only that the failure line coincides with the critical state, but also that the development of volumetric strain during shearing was not sensitive to the initial confining pressure. In both isotropically and anisotropically consolidated undrained tests, a so-called “reverse behaviour” was consistently observed. The results were also interpreted in the critical state framework. The critical and steady state (CS/SS) data were found to trace along the same curve in e–log( p′) space, irrespective of the stress history and effective stress paths. A comparison between the isotropic consolidation line (ICL) and critical state (CS) curve showed that a small amount of fines can significantly change the shape and position of the ICL relative to the CS curve. Furthermore, the soil behaviour manifested in both drained and undrained shearing led to the development of a modified state parameter.

The Modified Maximum Shear Stress Failure Theory of Ductile Material

2015 ◽  
Vol 727-728 ◽  
pp. 99-102
Author(s):  
Wen Lih Chen ◽  
King Leung Wong ◽  
Yu Feng Chang
Keyword(s):  
Shear Stress ◽  
Stress Ratio ◽  
Maximum Shear Stress ◽  
Ductile Material ◽  
Material Failure ◽  
Fourth Quadrant ◽  
Ductile Materials ◽  
Failure Theory ◽  
Failure Theories ◽  
Failure Line

In this study, the maximum and smallest vertical principle stresses σ1 and σ3 as well as maximum shear stress τmax distributions, obtained from Mohr circle in each quadrant, are used to investigate the applicability of various ductile material failure theories. Based on the yield tensile stress σyt equals to yield compressive stress σyc (σyt=σyc=σy) and the known practical yield shear stress and yield stress ratio τy/σy=0.42~0.75 of ductile materials, we prove that the maximum vertical stress failure theory cannot be applied to the first quadrant (σ1>σ3≧0) as well as the third quadrant (σ3<σ1≦0) while τy/σy< 0.5, and it does also not applicable to the second or fourth quadrant (σ1>0 and σ3<0). In this study, the modified maximum shear stress failure line can be fit all ductile material depending on τy/σy=0.42~0.75 in all quadrants, thus the more reasonable results can be obtained.

CRUSHING CHARACTERISTICS OF SOIL PARTICLE ON THE EFFECT OF STRESS PATH

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Keigo Fukuda ◽  
Haruyuki Yamamoto
Keyword(s):  
Axial Compression ◽  
Mechanical Characteristics ◽  
Shear Failure ◽  
Stress Path ◽  
Deviatoric Stress ◽  
Particle Crushing ◽  
Principal Stresses ◽  
The Mean ◽  
Lode Angle ◽  
Failure Line

In previous studies, we have conducted tests under various conditions of stress for the particle crushing. Anyway, it is necessary to perform the crushing test that assumed stress conditions in ground under controlled each principal stresses individually, to find the mechanical characteristics of the soil with particle crushing. Therefore, the purpose of this study is to confirm the effect for particle crushing under various stress paths in the combination of principal stresses. We planned four combinations of principal stresses when operate the mean stress p and deviatoric stress q up to the Shear Failure Line (SFL) on the 𝜋-plane. First, we set tri-axial extension test as Lode angle 𝛳=60° and tri-axial compression test as 𝛳=0°, and set two of the remainder as 𝛳=40°, 20°. The crushing tests are carried out using the high pressure true tri-axial compression apparatus under the planned stress paths. As a result, the progress of the particle crushing becomes active in order of 𝛳=40°, 20°, 60°, 0°, and found out that deviatoric stress q has essential effect on the particle crushing.

On the Design of Bolted Connections With Gaskets Subjected to Fatigue Loading

1977 ◽  
Vol 99 (2) ◽  
pp. 388-393 ◽  
Author(s):  
M. O. M. Osman ◽  
W. M. Mansour ◽  
R. V. Dukkipati
Keyword(s):  
Design Method ◽  
Design Procedure ◽  
Critical Diameter ◽  
Fatigue Loading ◽  
Dynamic Force ◽  
Bolted Connections ◽  
Bolted Connection ◽  
Stiffness Constant ◽  
Failure Line ◽  
Bolt Diameter

Bolted connections subjected to fatigue loading are usually considered to be the “weak point” in a design. They usually are highly preloaded to increase their resistance to external dynamic loading resulting in selecting large bolt diameters. This paper presents a design method for calculating an optimal bolt diameter required for a specific fatigue-loading situation. When load is applied to the bolted connection, the bolt tensile stress increases and the members undergo a decrease in compression. Based on the fact that the decrease in the deformation of the connected members must be equal to the increase in the deformation of the bolt, expressions are derived for maximum and minimum forces and stresses on the bolt. Using Soderberg’s failure line, an expression is developed for bolt diameter. It implies that there exists an optimal safe bolt diameter satisfying the loading conditions. Using a lower-bound value of bolt preloading produced an expression for the critical diameter of the bolt in terms of maximum and minimum dynamic force applied, the yield strength of bolt material, the factor of safety, and the stiffness constant. Examples are given to illustrate the design procedure.

scholarly journals Soil shear strength under non-irrigated and irrigated short duration grazing systems

2010 ◽  
Vol 34 (3) ◽  
pp. 631-638 ◽  
Author(s):  
Rita de Cássia Ribeiro Carvalho ◽  
Wellington Willian Rocha ◽  
José Cardoso Pinto ◽  
Bruno da Silva Pires ◽  
Moacir de Souza Dias Junior ◽  
...  
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Correction Factor ◽  
Soil Compaction ◽  
Strength Properties ◽  
Natural Forest ◽  
Pasture Management ◽  
Apparent Cohesion ◽  
Total Study Area ◽  
Failure Line

Pasture productivity can drop due to soil compaction caused by animal trampling. Physical and mechanical alterations are therefore extremely important indicators for pasture management. The objective of this research was to: draw and evaluate the Mohr failure line of a Red Yellow Latossol under different pasture cycles and natural forest; calculate apparent cohesion; observe possible physical alterations in this soil; and propose a correction factor for stocking rates based on shear strength properties. This study was conducted between March/2006 and March/2007 on the Experimental Farm of Fundação de Ensino Superior de Passos, in Passos, state of Minas Gerais. The total study area covered 6 ha, of which 2 ha were irrigated pasture, 2 ha non-irrigated pasture and 2 ha natural forest. Brachiaria brizantha cv. MG-5 Vitória was used as forage plant. The pasture area was divided into paddocks. The Mohr failure line of samples of a Red Yellow Latossol under irrigated pasture equilibrated at a tension of water content of 6 kPa indicated higher shear strength than under non-irrigated pasture. The shear strength under irrigated pasture and natural forest was higher than under non-irrigated pasture. At a tension of water content of 33 kPa no difference was found in shear strength between management and use. Possible changes in soil structure were caused by apparent cohesion. The values of the correction factor were close to 1, which may indicate a possible soil compaction in prolonged periods of management.

Strengthening of a concrete masonry wall subject to lateral load with sprayed glass-fibre-reinforced polymer

2010 ◽  
Vol 37 (10) ◽  
pp. 1315-1330 ◽  
Author(s):  
M. A. Haddad ◽  
E. Shaheen ◽  
G. A. Parsekian ◽  
D. Tilleman ◽  
N. G. Shrive
Keyword(s):  
Glass Fibre ◽  
Lateral Load ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Reinforced Polymer ◽  
Concrete Masonry ◽  
Glass Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced ◽  
Failure Line

Unreinforced hollow concrete masonry walls could be used to construct basements if strengthened to resist the lateral load. Two face-shell-bedded concrete masonry walls were constructed, 3 m high by 6 m long. As a simple strengthening technique, one wall was sprayed with glass-fibre-reinforced polymer (GFRP) on one side to a nominal average thickness of 5 mm. The walls were subjected to distributed point loading simulating increasing pressure from top to bottom of the wall. Support conditions were applied to simulate the walls being part of a basement. The plain wall failed with a failure line cracking pattern at a lateral load of 44 kN. The sprayed wall failed in a much more brittle fashion when the load reached 330 kN. The GFRP suffered a mode III tear at the bottom course. The results indicate that spraying a plain masonry wall with GFRP increases its ability to resist lateral load considerably, and that the process could be improved in terms of both the thickness of the layer and the area of wall covered to achieve a specific target. The two walls were analyzed using the yield-line, fracture-line, and failure-line methods. The failure-line method was improved by accounting for the stiffness orthotropy of masonry and gave the most accurate prediction of these plastic design methods. A finite element model of the masonry provided the most accurate prediction of capacity.

Influences on Permanent Deformation Behavior of Unbound Granular Materials

1996 ◽  
Vol 1547 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Fredrick Lekarp ◽  
Ian Reginald Richardson ◽  
Andrew Dawson
Keyword(s):  
Granular Materials ◽  
Stress Level ◽  
Deformation Behavior ◽  
Permanent Deformation ◽  
Repeated Loading ◽  
Permanent Strain ◽  
Unbound Granular Materials ◽  
Failure Line ◽  
Static Failure ◽  
French Model

The results of a research program aimed at characterizing the permanent deformation behaviors of different types of unbound aggregates under repeated loading are summarized. Tests were performed in a triaxial or hollow-cylinder apparatus, depending on the grading of the materials. The scope of the research was to assess the relationship between total permanent axial strain and both the number of load applications and the stress level. The test results were used to verify a model recently developed in France in which attempts are made to predict the long-term behaviors of granular materials. The French model is examined with particular reference to its validity on the effect of stress level on permanent deformation of unbound granular materials. The results of the study indicate that the French model is generally successful in predicting the permanent strain for a given number of load applications. For one of the materials, however, the model did not seem to fit the data well. The French model also suggests that the variation in total permanent strain with stress level is related to the static failure line and could be determined by comparing the maximum shear stress ratio with the slope of the estimated failure line. This is discussed and shown to be questionable because it results in either unreasonable failure parameters or a very low level of correlation with the observations. An attempt was made to modify the French model, but that also proved to be unsuccessful. The concept of relating the permanent deformation behavior to the static failure condition of the material is therefore questioned.

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