scholarly journals The Behavior of a Thread-Bar Grouted Anchor in Soils from Local Strain Monitoring

2020 ◽  
Vol 10 (20) ◽  
pp. 7194
Author(s):  
Paolo Ruggeri ◽  
Viviene M. E. Fruzzetti ◽  
Giuseppe Scarpelli
Keyword(s):  
Shear Strength ◽  
Load Capacity ◽  
Poor Performance ◽  
Local Strain ◽  
International Standards ◽  
Strain Gauges ◽  
Fixed Length ◽  
Strain Monitoring ◽  
Sand Deposit ◽  
Low Shear

International standards discourage the use of grouted anchors with a fixed length exceeding 10 m. However, grouted anchors with a fixed length between 10 and 20 m are frequently used in Italy to transfer high loads to ground with poor geotechnical properties. This paper presents the results of investigation tests on an anchor with a length of 36 m, of which 18 m is fixed, sloping 40° from the horizontal; the anchor is comprised of a reinforced thread-bar which was instrumented with strain gauges and founded in nonhomogeneous ground, a sand deposit followed by marly clay. The test aimed at investigating the progressive mobilization of the shear strength along the foundation. The results indicate a very low shear strength offered by the sand, probably disturbed by the drilling, and an unusually fast mobilization of the shear strength in the marly clay at the deep end of the anchor. The results are particularly useful to identify the reasons for the observed poor performance of the grouted anchor. In particular, the study once again made it clear how important the influence of the execution details on reaching the expected load capacity may be, and likewise the practice of investigation tests on suitably instrumented test anchors.

Parametric study of multi-story, perforated, partially grouted masonry walls subjected to in-plane cyclic actions

2020 ◽  
Author(s):  
Klaus Medeiros ◽  
Kyle Chavez ◽  
Fernando S. Fonseca ◽  
Guilherme Parsekian ◽  
Nigel G. Shrive
Keyword(s):  
Experimental Data ◽  
Shear Strength ◽  
Aspect Ratio ◽  
Load Capacity ◽  
Axial Stress ◽  
Reinforcement Ratio ◽  
Masonry Walls ◽  
Finite Element Models ◽  
Initial Stiffness ◽  
Vertical Reinforcement

Finite element models were developed to assess the influence of several parameters on the load capacity, deflection, and initial stiffness of multi-story, partially grouted masonry walls with openings. The base model was validated with experimental data from three walls. The analyses indicated that the load capacity of masonry walls was considerably sensitive to the ungrouted and grouted masonry strengths and mortar shear strength; moderately sensitive to the vertical reinforcement ratio and aspect ratio; slightly sensitive to the axial stress; and almost insensitive to the opening size, reinforcement spacing, and horizontal reinforcement ratio. The deflection of the walls had well-defined correlations with the masonry strength, vertical reinforcement, axial stress and aspect ratio. The initial stiffness was especially sensitive to the axial stress and the aspect ratio, but weakly correlated with the opening size, and the spacing and size of the reinforcement.

scholarly journals Microscale local strain gauges based on visible micro-disk lasers embedded in a flexible substrate

2018 ◽  
Vol 26 (13) ◽  
pp. 16797 ◽  
Author(s):  
Taojie Zhou ◽  
Jie Zhou ◽  
Yuzhou Cui ◽  
Xiu Liu ◽  
Jiagen Li ◽  
...  
Keyword(s):  
Flexible Substrate ◽  
Local Strain ◽  
Strain Gauges

Dynamic bending of plates with low shear strength

1972 ◽  
Vol 4 (4-6) ◽  
pp. 544-549
Author(s):  
B. L. Pelekh ◽  
G. A. Teters
Keyword(s):  
Shear Strength ◽  
Dynamic Bending ◽  
Low Shear

Flexure of beams with low shear strength on an elastic foundation

1971 ◽  
Vol 3 (5) ◽  
pp. 582-585 ◽  
Author(s):  
Yu. M. Tarnopol'skii ◽  
A. V. Roze ◽  
R. P. Shlitsa
Keyword(s):  
Shear Strength ◽  
Elastic Foundation ◽  
Low Shear

Behavior of multidirectional friction dampers

2020 ◽  
Vol 26 (21-22) ◽  
pp. 1969-1979
Author(s):  
Recep Suk ◽  
Gökhan Altintaș
Keyword(s):  
Structural Damage ◽  
Load Capacity ◽  
Spherical Surface ◽  
Poor Performance ◽  
Surface Friction ◽  
Building Stock ◽  
Seismic Damper ◽  
Earthquake Performance ◽  
Production Techniques ◽  
Property Losses

Earthquakes are catastrophic events causing loss of lives, injuries, and extensive losses in properties. Majority of the life and property losses of earthquakes are dependent on the incapabilities of the building stock to resist earthquakes. Although unsuitable design, analyses, and production techniques play a major role as the main reasons for the poor performance of buildings against earthquakes, buildings constructed in accordance with building codes also suffer from the devastating impact of earthquakes. In this context, the lack of proper management and adequate damping of the energy caused by earthquakes is a major cause of structural damage in earthquakes. The efficiency of conventional basic elements in structures with energy damping is very limited and may not be sufficient for the damping of a large amount of earthquake-induced energy. Thanks to the rapid advances in technology and associated engineering techniques, numerous new products, and production and calculation techniques are underway to mitigate the devastating effects of earthquakes on buildings. In this study, it was aimed to theoretically and experimentally investigate the performance of a versatile friction-type seismic damper that eliminates earthquake energy. The damper is designed using a spherical surface friction joint to respond to all loads regardless of the loading direction. The damper can be easily adjusted to the desired capacity by means of bolt tensioning elements. Experiments have been carried out for various shear loads and damping parameters. Furthermore, numerical analysis of the model was carried out by use of the finite element method. The results of this study revealed that the shear load capacity of the device did not change at different frequencies. Analyzing the effect of the equipment on a structure, it was understood that it reduces roof displacement and periods of the structure. The analysis revealed that the damper significantly improved the earthquake performance of the structure.

scholarly journals Behavior of Partially Grouted Concrete Masonry Walls under Quasi-Static Cyclic Lateral Loading

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2424
Author(s):  
Sebastián Calderón ◽  
Laura Vargas ◽  
Cristián Sandoval ◽  
Gerardo Araya-Letelier
Keyword(s):  
Shear Strength ◽  
Aspect Ratio ◽  
Load Capacity ◽  
Masonry Walls ◽  
Lateral Stiffness ◽  
Edge Elements ◽  
Vertical Reinforcement ◽  
Concrete Masonry ◽  
Resistance Degradation ◽  
Concrete Masonry Walls

Eight partially grouted (PG-RM) concrete masonry walls were tested to study the influence of the strength and width of blocks, the wall aspect ratio, the horizontal and vertical reinforcement ratio, and the presence of edge elements (flanges). The results were analyzed in terms of the failure mode, damage progression, shear strength, lateral stiffness degradation, equivalent viscous damping ratio, and displacement ductility. Additionally, the performances of some existing shear expressions were analyzed by comparing the measured and predicted lateral load capacity of the tested walls. Based on the results, a slight increment in the lateral stiffness was achieved when employing stronger blocks, while the shear strength remained constant. Besides, increasing the width of concrete blocks did not have a significant effect on the shear strength nor in the initial tangential stiffness, but it generated a softer post-peak strength degradation. Increasing the wall aspect ratio reduced the brittleness of the response and the shear strength. Reducing the amount of vertical reinforcement lowered the resulting shear strength, although it also slowed down the post-peak resistance degradation. Transversal edge elements provided integrity to the wall response, generated softer resistance degradation, and improved the symmetry of the response, but they did not raise the lateral resistance.

Enhanced Instruction of Engineering Mechanics Using Curvature Experiments

2009 ◽  
Author(s):  
Byron L. Newberry
Keyword(s):  
Low Cost ◽  
Structural Response ◽  
Local Strain ◽  
Strain Gauges ◽  
Local Curvature ◽  
Post Process ◽  
Single Use ◽  
Strain Stress ◽  
Engineering Mechanics ◽  
Point Data

Resistive strain gauges are the most commonly used experimental devices for stress analysis. Their versatility stems from their ability to directly measure local strain on the surface of a structure, almost regardless of geometry. This strength can represent an educational limitation, however. Measurements made using strain gauges tend to provide results without students assessing or understanding the global structural response; limiting the insight gained and the instructional value of the experiment. Herein a low-cost device is presented that allows accurate measurement of local curvature in a beam. Once the local curvature is known, the elastic equations governing the beam may be used to calculate the local strain, stress, and deflection. The educational strength of the device is that students are forced to understand the interrelation of stress, strain, and deflection to post-process the experimental results. The device, though limited to beam geometries, has proven effective in helping students master engineering mechanics. It also allows investigation of the entire beam without added expense; as the device is not permanently affixed to one location. This is a significant advantage compared to strain gauges that provide only point data and are single-use. Details of the device itself, how it has been incorporated into the curriculum, and data assessing its effectiveness within a junior-level course are presented.

scholarly journals Use of Particle Image Velocimetry (PIV) technique to measure strains in geogrids

2019 ◽  
Vol 92 ◽  
pp. 12007
Author(s):  
Chaminda Gallage ◽  
Chamara Jayalath
Keyword(s):  
Tensile Strength ◽  
Retaining Wall ◽  
Local Strain ◽  
Tensile Tests ◽  
Experimental Program ◽  
Strain Gauges ◽  
Data Logging ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Secant Stiffness

Geosynthetics are widely used in Geotechnical Engineering to reinforce soil/gravel in pavements, retaining wall backfills, and embankments. It is important to measure strains in geogrids in the determination of their strength parameters such as tensile strength and secant stiffness, and in evaluating their performances in geogrid-reinforced structures. Strain gauges are commonly used in measuring strains in geogrids. However, it is important to verify the strains measured by strain gauges as these strains are affected by the data logging device, gauge factors, quality of bonding between grain gauge and geogrid, and temperature. Therefore, this study was conducted to verify the performance of strain gauges attached to Geogrids and also to investigate the possibility of using PIV technique and GeoPIV-RG software to measure the local strains developed in a geogrid specimen under tensile testing in the laboratory. In the experimental program of this study, six composite geogrid specimens were tested for tensile strength (wide-width tensile tests) while measuring/calculating its tensile strain by using strain gauges attached to the specimens, Geo-PIV-RG analysis and crosshead movements of Instron apparatus. Good agreement between the strains obtained from strain gauges and geoPIV-RG analysis was observed for all the tests conducted. These results suggest that the PIV technique along with geoPIV-RG program can effectively be used to measure the local strain of geogrids in the laboratory tests. It was also able to verify that properly installed strain gauges are able to measure strain in the geogrids which are used in the field applications.

scholarly journals Application of FRP Bolts in Monitoring the Internal Force of the Rocks Surrounding a Mine-Shield Tunnel

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2763 ◽  
Author(s):  
Zhen Liu ◽  
Cuiying Zhou ◽  
Yiqi Lu ◽  
Xu Yang ◽  
Yanhao Liang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Internal Force ◽  
Shield Tunnel ◽  
Corrosive Environment ◽  
High Tensile Strength ◽  
Technological Support ◽  
Remote Monitoring System ◽  
Initial Support ◽  
Low Shear

Monitoring the internal force of the rocks surrounding a mine-shield tunnel for the initial support of a mine-shield tunnel, in complex geological and hydrological environments, requires bolts with specific features such as high tensile strength, low shear strength, good insulation and resistance to corrosion. As such, internal force monitoring has become an important issue in safety monitoring for such tunneling projects. In this paper, the adaptability of a mine-shield tunnel project in a corrosive environment is investigated. A fiberglass reinforced plastic (FRP) bolt with high tensile strength, low shear strength, resistance to fatigue, non-conductivity and resistance to corrosion is used as a probe in tandem with an anchor-head dynamometer to monitor the internal force of the rocks surrounding a mine-shield tunnel for initial support. Additionally, solar energy collection technology is introduced to create a remote monitoring system. Using a 2.5 km long railway tunnel located in the northeast of the Pearl River Delta of China as a case study, the present study shows that, compared with a conventional steel bolt, the FRP bolt has advantages, such as avoidance of the risks associated with the shield machine, insulation and resistance to corrosion. As a probe, the response of the FRP bolt to events such as a blasting vibration and a construction disturbance that results in internal changes in the surrounding rock demonstrates a clear pattern that is appropriate for monitoring the internal force of the rocks surrounding a mine-shield tunnel in a corrosive environment. FRP bolt-based monitoring not only provides new technological support for controlling the risk involved in the initial support of a mine-shield tunnel but can also be widely deployed in projects with special requirements for disassembly, conductivity and corrosion.

Sign in / Sign up

Export Citation Format

Share Document