Large model test of prestressed carbon fibre reinforced polymer ground anchors

2005 ◽  
Vol 32 (6) ◽  
pp. 1064-1074 ◽  
Author(s):  
Burong Zhang ◽  
Brahim Benmokrane
Keyword(s):  
Rock Mass ◽  
Carbon Fibre ◽  
Model Test ◽  
Load Transfer ◽  
Strain Gauges ◽  
Tensile Behaviour ◽  
Distribution Profile ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

This paper presents a full-scale prestressed ground anchor model test with carbon fibre reinforced polymer (CFRP) 9-bar tendons. The main objectives of this laboratory study were to evaluate the serviceability of the developed bond-type anchorage for post-tensioning applications with CFRP multibar tendons and to study load transfer mechanism of CFRP multibar tendons to surrounding rock mass. A cement-based mortar-filled steel tube was used to simulate a rock mass environment. Extensive instrumentation including resistance strain gauges, fibre optic sensors, embedded strain gauges, and linear variable displacement transducers (LVDTs) were used to monitor the behaviour of the anchor. The test results show that the tested CFRP 9-bar anchor presents an acceptable tensile behaviour under a load of 0.6fpu in accordance with existing codes. The CFRP multibar anchor presents a similar strain distribution profile as that for conventional steel anchors, except giving a shorter load transfer length. It is expected that CFRP 9-bar anchors require a minimum anchor bonded length of 2000 mm with plain cement grouts.Key words: anchor, anchorage, FRP, tendon, slip.

Using digital image correlation to evaluate the bond between carbon fibre-reinforced polymers and timber

2021 ◽  
pp. 147592172110060
Author(s):  
Hugo C Biscaia ◽  
João Canejo ◽  
Shishun Zhang ◽  
Raquel Almeida
Keyword(s):  
Digital Image Correlation ◽  
Carbon Fibre ◽  
Digital Image ◽  
Image Correlation ◽  
Strain Gauges ◽  
Correlation Technique ◽  
Digital Image Correlation Technique ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

The use of optic measurements such as digital image correlation to take strain measurements of fibre-reinforced polymers bonded to a substrate has been on the increase recently. This technique has proven to be useful to fully characterize the bond behaviour between two materials. Although modern digital cameras can take high-definition photos, this task is far from simple due to the tiny displacements that need to be measured. Consequently, digital image correlation measurements lead to relative errors that, at an initial stage of the debonding process, are higher than those calculated close to the debonding of the fibre-reinforced polymer from the substrate. This study aims to evaluate and analyse the use of the digital image correlation technique on the bond between carbon fibre-reinforced polymer laminates and timber when subjected to a pull-out load consistent with fracture Mode II. To allow the quantification of the relative errors obtained from the digital image correlation measurements during the full debonding process, several strain gauges were used to measure the strains in the carbon fibre-reinforced polymer composite. The accuracy of the digital image correlation measurements is analysed by comparing it with those obtained from the strain gauges, which is a very well-established measuring technique. Another contribution of this study is to check the versatility of the digital image correlation measurements on a broader range of situations. To that end, several timber prisms were bonded with seven different bonding techniques with and without the installation of a mechanical anchorage at the carbon fibre-reinforced polymer unpulled end. The results showed that the digital image correlation technique was able to track the slips calculated from the strain gauge measurements until the debonding load, but after that, some difficulties to measure the displacements of the anchored carbon fibre-reinforced polymer-to-timber joints were detected. The digital image correlation technique also over predicted bond stresses when compared with those taken from the strain gauges, which led to bond–slip relationships with higher bond stresses.

scholarly journals A novel particle-filled carbon-fibre reinforced polymer model composite tailored for the application of digital volume correlation and computed tomography

2020 ◽  
pp. 002199832096638
Author(s):  
E Schöberl ◽  
C Breite ◽  
S Rosini ◽  
Y Swolfs ◽  
MN Mavrogordato ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Carbon Fibre ◽  
Image Correlation ◽  
Homogeneous Distribution ◽  
Tensile Behaviour ◽  
Digital Volume Correlation ◽  
Model Composite ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

This paper presents the development of novel Carbon-Fibre Reinforced Polymer (CFRP) laminates, tailored for the application of Digital Volume Correlation (DVC) and Computed Tomography (CT) to experimental mechanics analyses of these materials. Analogous to surface-based Digital Image Correlation (DIC), DVC is a relatively novel volumetric method that utilizes CT data to quantify internal three-dimensional (3D) displacements and implicit strain fields. The highly anisotropic and somewhat regular/self-similar microstructures found in well-aligned unidirectional (UD) materials at high fibre volume fractions are intrinsically challenging for DVC, especially along the fibre direction at microstructural length-scales on the order of a few fibre diameters. To permit the application of DVC to displacement and/or strain measurements parallel to the fibre orientation, the matrix was doped with a sparse population of sub-micrometre particles to act as displacement trackers ( i.e. fiducial markers). Barium titanate particles (400 nm, ∼1.44 vol. %) were found to offer the most favourable compromise between contrast in CT images and the ability to obtain a homogeneous distribution in 3D space with sufficient particle compactness for local DVC analyses. This property combination was selected following an extensive Micro-focus Computed Tomography (µCT)-based qualitative assessment on a wide test matrix, that included 38 materials manufactured with a range of possible particle compositions, mean sizes and concentrations. By comparing the tensile behaviour of the particle-adapted material alongside its particle-free counterpart, we demonstrate through the application of in situ Synchrotron Radiation Computed Tomography (SRCT) that the macro- and micromechanical responses of the newly developed CFRP are consistent with standard production materials indicating its suitability as a model system for mechanistic investigations.

Influence of Ply Stacking Sequences on the Impact Response of Carbon Fibre Reinforced Polymer Composite Laminates

2019 ◽  
Author(s):  
Kristian Gjerrestad Andersen ◽  
Gbanaibolou Jombo ◽  
Sikiru Oluwarotimi Ismail ◽  
Segun Adeyemi ◽  
Rajini N ◽  
...  
Keyword(s):  
Carbon Fibre ◽  
Polymer Composite ◽  
Composite Laminates ◽  
Impact Response ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
The Impact
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