scholarly journals Experimental and Numerical Investigation on the Steel Reinforced Grout (SRG) Composite-to-Concrete Bond

2020 ◽  
Vol 4 (4) ◽  
pp. 182
Author(s):  
Luciano Ombres ◽  
Salvatore Verre
Keyword(s):  
Bond Length ◽  
Failure Modes ◽  
Peak Load ◽  
Element Model ◽  
Test Results ◽  
Shear Tests ◽  
Bond Slip ◽  
Bond Behavior ◽  
Direct Shear Tests ◽  
Inorganic Matrix

In the paper, the bond between a composite strengthening system consisting of steel textiles embedded into an inorganic matrix (steel reinforced grout, SRG) and the concrete substrate, is investigated. An experimental investigation was carried out on medium density SRG specimens; direct shear tests were conducted on 20 specimens to analyze the effect of the bond length, and the age of the composite strip on the SRG-to-concrete bond behavior. In particular, the tests were conducted considering five bond length (100, 200, 250, 330, and 450 mm), and the composite strip’s age 14th, 21st, and 28th day after the bonding. Test results in the form of peak load, failure modes and, bond-slip diagrams were presented and discussed. A finite element model developed through commercial software to replicate the behavior of SRG strips, is also proposed. The effectiveness of the proposed numerical model was validated by the comparison between its predictions and experimental results.

scholarly journals Bond Behavior between Concrete and Self-Expansion Polymer Material under Normal Pressures

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Xinxin Li ◽  
Fuming Wang ◽  
Hongyuan Fang ◽  
Dan Zheng ◽  
Yingchun Fu
Keyword(s):  
Bond Strength ◽  
Failure Modes ◽  
Concrete Strength ◽  
Normal Pressure ◽  
Element Model ◽  
Test Results ◽  
Shear Tests ◽  
Direct Shear Tests ◽  
Peak Point ◽  
Polymer Density

Self-expansion polymer grouting technology is a new rapid trenchless method for repairing leakage and subsidence of underground concrete structures. The bond between polymer and concrete is critical to determine the ultimate conditions of repaired concrete. In this paper, a series of direct shear tests were performed to investigate the influence of normal pressure on the shear bond properties between self-expansion polymer and concrete with different polymer density and concrete strength. Results indicate that failure modes and bond strength are greatly influenced by the normal pressure for specimens with a lower polymer density. For a given normal pressure, the bond strength linearly increases with the increasing polymer density. As the polymer density increased up to 0.43 g/cm3, the increased ratio decreases with the polymer density. Moreover, the displacement at the peak point reduces with an increase in polymer density. Finally, a finite element model is proposed to evaluate the bond strength for specimen failure in concrete and verified with the test results.

Bond Behavior between Tuff and Fired-Clay Brick Masonry Blocks and SRG Composites

2019 ◽  
Vol 817 ◽  
pp. 118-125
Author(s):  
Giulia Baietti ◽  
Elisa Franzoni ◽  
Giovanni Quartarone ◽  
Alberto Fregni ◽  
Christian Carloni
Keyword(s):  
Salt Crystallization ◽  
Clay Brick ◽  
Shear Tests ◽  
Composite Matrix ◽  
Bond Behavior ◽  
Direct Shear Tests ◽  
Clay Bricks ◽  
Historical Structures ◽  
Salt Distribution ◽  
Masonry Units

This paper presents the results of single-lap direct shear tests on steel reinforced grout (SRG) strips bonded to fired-clay brick and tuff masonry blocks. For this experimental campaign, fifteen masonry blocks were constructed and reinforced with SRG composite strips. Fired-clay bricks and tuff blocks herein employed were collected from demolished historical structures in Modena and Naples (Italy), respectively. Eight out of fifteen blocks were subjected to an artificial weathering procedure to induce salt crystallization, and therefore reproduce the degradation conditions that the buildings could be subjected to during their life. Bond behavior of unconditioned strengthened specimens (i.e. SRG-masonry joints) was compared with the behavior of conditioned joints. Salt distribution, open porosity, and water absorption of brick and tuff masonry units as well as of the SRG composite matrix were analyzed to understand if and how the salt crystallization influenced the adhesion between the SRG strip and the block.

scholarly journals Comparison of Mechanical Properties of Fiber-Reinforced Sand under Triaxial Compression and Direct Shear

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Reza Noorzad ◽  
Seyed Taher Ghoreyshi Zarinkolaei
Keyword(s):  
Shear Strength ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Polypropylene Fiber ◽  
Triaxial Tests ◽  
Direct Shear ◽  
Test Results ◽  
Peak Reduction ◽  
Shear Tests ◽  
Direct Shear Tests

AbstractThis research investigates the behavior of sand reinforced with polypropylene fiber. To do this, 40 direct shear tests and 40 triaxial tests were performed on the coastal beaches of Babolsar, a city in the North of Iran. The effect of parameters such as fiber content, length of fiber and normal or confining pressure on the behavior of Babolsar sand have been studied. In this study, four various fiber contents (0, 0.25, 0.5 and 1 percent), three different lengths of fiber (6, 12 and 18 mm) and four normal or confining pressures (50, 100, 200 and 400 kPa) have been employed. The test results show that fiber inclusion has a significant effect on the behavior of sand. In both direct shear and triaxial tests, the addition of fibers improved shear strength parameters (C, '), increased peak shear strength and axial strain at failure, and also limited the amount of post-peak reduction in shear resistance. The comparison of the test results revealed that due to better fiber orientation toward the direction of principal tensile strain in triaxial test as compared to direct shear tests, the fiber efficiency and its effect on soil behavior is much more significant in triaxial specimens.

Red Sandstone Aggregate Mixture Experimental Study of Dynamic Compaction High Fill Embankment

2014 ◽  
Vol 1065-1069 ◽  
pp. 696-701
Author(s):  
Zhao Jun Chen ◽  
Wen Li ◽  
Xiang Qu
Keyword(s):  
Experimental Study ◽  
Rayleigh Wave ◽  
Dynamic Compaction ◽  
Direct Shear ◽  
Test Results ◽  
Shear Tests ◽  
Red Sandstone ◽  
Direct Shear Tests ◽  
Water Intensity ◽  
Intensity Decay

Direct shear tests by laboratory to study the red sandstone aggregate mixture under the action of water intensity decay law, got red sandstone aggregate mixture, fill high subgrade compaction experimental study, tests showed that dynamic compaction compacted earth and rock mix fill embankment feasible, Rayleigh Wave test results show that the effect of dynamic compaction compaction good.

scholarly journals Bond Behavior between Steel Rebar and RCA Concrete after Exposure to Elevated Temperatures

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Wanjie Zou ◽  
Jiongfeng Liang ◽  
Dawei Liu ◽  
Guangwu Zhang
Keyword(s):  
Bond Strength ◽  
Elevated Temperatures ◽  
Coarse Aggregate ◽  
Test Results ◽  
Modified Model ◽  
Bond Slip ◽  
Bond Behavior ◽  
Steel Rebar ◽  
Exposure Temperature ◽  
Increasing Temperature

To explore the bond behavior between steel rebar and recycled coarse aggregate (RCA) concrete after exposure to elevated temperatures, an experimental study was carried out. The results demonstrated that the bond strength of RCA concrete pullout specimens decreased greatly with increasing temperature. As the exposure temperature elevated, the slope of the ascending portion of the bond-slip curves gradually declined, and the descending portion of the curves tended to flatten. A modified model was developed to predict the bond strength between RCA concrete and steel rebar after exposure to elevated temperature, and the predicted results showed a very good fit in the experimental test results. Besides, the proposed bond-slip relations for steel rebar in RCA concrete after elevated temperatures showed satisfactory agreement with test results.

Mechanical Properties of Fly Ash-Slag-Dredged Silt System Stimulated by Alkali

2013 ◽  
Vol 807-809 ◽  
pp. 1140-1146 ◽  
Author(s):  
Yi Xuan Chen ◽  
Xiu Li Sun ◽  
Zhi Hua Li
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Fly Ash ◽  
Construction Materials ◽  
Xrd Analysis ◽  
Test Results ◽  
X Ray Diffraction ◽  
Shear Tests ◽  
X Ray ◽  
Direct Shear Tests

The objective of this work is to investigate the stimulation effect of the addition of alkali on the fly ash and slag for stabilizing dredged silt. Based on the test results, a viable alternative for the final disposal of dredged silt as subgrade construction materials were proposed. For this purpose, several mixtures of dredged silt-fly ash-slag and alkali were prepared and stabilized/solidified. In this system, fly ash and slag were used as hardening agents (solidified materials) of dredged silt and alkali was used as activator of fly ash and slag. The shear strength of the mixture was tested by several direct shear tests. Furthermore, X-Ray Diffraction (XRD) analysis was used to determine the hydration products of the system. The specimens were tested in order to determine the shear strength changes versus hydration time and the alkali content. It is indicated that mechanical properties of solidified silt are improved significantly by addition of fly ash and slag stimulated by alkali.

Bond-Slip Constitutive Behavior between Fiber-Reinforced Polymer and Masonry

2012 ◽  
Vol 446-449 ◽  
pp. 3165-3170 ◽  
Author(s):  
Yi Zheng ◽  
Jin Qing Jia ◽  
Li Li ◽  
Shi Kuan You
Keyword(s):  
Constitutive Models ◽  
Bond Stress ◽  
Fiber Reinforced Polymer ◽  
Strain Gauges ◽  
Test Results ◽  
Hydraulic Jack ◽  
Bond Slip ◽  
Bond Behavior ◽  
Frp Composite ◽  
Reinforced Polymer

To study the bond behavior and the force transference of FRP plates adhered to masonry. In this paper, experiments of anchorage strength of FRP attached to masonry are done, a 100KN capacity hydraulic jack activated by a manual pump was used to load the specimen. The tensile strength was measured by using a loading transducer, and strain gauges were mounted directly onto the surface of the FRP composite to measure the strain during application of load. Besides the strain and bond stress development and distribution under every grade of loading were studied. Test results show that the maximum local bond stress is not influenced by the FRP bond length, instead it increases with masonry strength. At the same time, the local bond stress--slip curve is obtained. Based on the test results, two new bond stress-slip constitutive models between FRP and masonry were proposed and they turned out to be good matches to the experimental results, which indicate its valuable references for the corresponding codes and engineering applications.

scholarly journals A Double-Acting Piezoelectric Actuator for Helicopter Active Rotor

Actuators ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 247
Author(s):  
Jinlong Zhou ◽  
Linghua Dong ◽  
Weidong Yang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Piezoelectric Actuator ◽  
Performance Test ◽  
Failure Modes ◽  
Element Model ◽  
Test Results ◽  
Trailing Edge ◽  
Trailing Edge Flaps ◽  
Piezoelectric Stacks

An active rotor with trailing-edge flaps is an effective approach to alleviate vibrations and noise in helicopters. In this study, a compact piezoelectric actuator is proposed to drive trailing-edge flaps. The two groups of piezoelectric stacks accommodated in the actuator operate in opposition, and double-acting output can be realized through the differential motion of these stacks. A theoretical model and a finite element model are established to predict the output capability of this actuator, and structural optimization is performed using the finite element model. A prototype is built and tested on a benchtop to assess its performance. Test results demonstrate that the actuator stiffness reaches 801 N/mm, and its output stroke is up to ± 0.27 mm when subjected to actuation voltage of 120 V. Agreement between measurements and simulations validates the accuracy of the established models. In addition, actuator outputs in failure modes are measured by canceling the supply voltage of one group of piezoelectric stacks. In this condition, the actuator can still generate acceptable outputs, and the initial position of the output end remains unchanged. Simulations and test results reveal that the proposed actuator achieves promising performance, and it is capable to be applied to a helicopter active rotor.

scholarly journals Experimental and Numerical Investigation of Short-Term Behavior of Partially Precast and Partially Encased Composite Beams

2020 ◽  
Vol 28 (3) ◽  
pp. 29-39
Author(s):  
Liufeng Zhang ◽  
Yinghua Yang
Keyword(s):  
Finite Element ◽  
Load Capacity ◽  
Peak Load ◽  
Element Model ◽  
Bending Test ◽  
Test Results ◽  
Short Term ◽  
Element Analysis ◽  
The Finite Element Model ◽  
Bending Response

AbstractIn this paper, the short-term behavior of a new partially pre-cast and partially encased composite (PPEC) beam is studied. This paper reports the results of a 4-point bending test on a full-scale PPEC beam and sets out the load displacement response, short-term stiffness, peak load capacity and failure mode of the proposed PPEC beam. In addition, a finite element analysis of the PPEC beam is carried out, and the numerical simulation results are compared with the test results. The results show that the finite element model can reflect the bending response of the PPEC beam. In this paper, three different calculation methods are used to compare the deflection of the PPEC beam. The results show that the values calculated by the bending-shear coupling method formula agree relatively well with the test results.

scholarly journals Shear strength behaviour of sand-bentonite mixtures with pumice additivite under high temperature

2020 ◽  
Vol 205 ◽  
pp. 04004
Author(s):  
Esra Güneri ◽  
Yeliz Yükselen Aksoy
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Room Temperature ◽  
Engineering Properties ◽  
Direct Shear ◽  
Test Results ◽  
Soil Behavior ◽  
Shear Tests ◽  
Volume Deformation ◽  
Direct Shear Tests

Depending on increase in the number and type of energy geostructures, studies on the change in soil behavior against heat increase becomes more important. The engineering properties such as permeability, volume deformation of surrounding soils around energy structures mustn’t alter in the presence of heat and thermal cycles. Pumice is a material used in many fields especially for thermal insulation. For that reason, pumice can be used for increasing the resistance of soils in the presence of heat. In this study, the shear strength behavior of sand-bentonite mixtures was investigated with pumice additive under high temperature. In the experiments, 10% and 20% pumice were added to 10% and 20% sand-bentonite mixtures and compaction, direct shear tests were conducted. The direct shear tests were performed both room temperature and under 80°C. The results have shown that the pumice additive increased the shear strength of sand-bentonite mixtures under high temperature when compared the test results under room temperature.

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