scholarly journals Some Key Aspects in the Mechanics of Stress Transfer Between SRG and Masonry

2020 ◽  
Vol 10 (20) ◽  
pp. 7303
Author(s):  
Giulia Baietti ◽  
Tommaso D’Antino ◽  
Christian Carloni
Keyword(s):  
Stress Transfer ◽  
High Strength ◽  
Active Role ◽  
Fiber Reinforced ◽  
Suitable Alternative ◽  
Existing Structures ◽  
Direct Shear Tests ◽  
Frp Composites ◽  
Mortar Matrix

The use of composite materials to strengthen masonry structures has become common practice within the civil engineering community. Steel-reinforced grout (SRG), which comprises high-strength steel fibers embedded in a mortar matrix, is part of the family of the fiber-reinforced cementitious matrix (FRCM) composites that represent a suitable alternative to fiber-reinforced polymer (FRP) composites for strengthening existing structures. Although studies on FRCMs have already reached a certain level of maturity, some key issues remain open, such as the role of matrix type and layout, substrate properties, and test rate. This paper focuses on some of these issues. The results of single-lap direct shear tests on masonry blocks strengthened with SRGs are presented to analyze the bond behavior between the composite material and the substrate. Four aspects are considered: (1) the change in the width of the SRG mortar matrix while keeping the width of the fiber sheet fixed; (2) the type of mortar used for the SRG; (3) the influence of the test rate, and (4) the type of substrate (i.e., concrete vs. masonry). The results obtained indicate the active role of the matrix layout and the importance of the test rate, encouraging further investigations to clarify these aspects.

An Investigation of the Debonding Mechanism between FRCM Composites and a Masonry Substrate

2017 ◽  
Vol 747 ◽  
pp. 382-389 ◽  
Author(s):  
Mattia Santandrea ◽  
Gilda Daissè ◽  
Claudio Mazzotti ◽  
Christian Carloni
Keyword(s):  
Failure Modes ◽  
Stress Transfer ◽  
High Strength ◽  
Steel Fibers ◽  
Vapor Permeability ◽  
Fiber Reinforced ◽  
Direct Shear Tests ◽  
Frp Composites ◽  
Load Carrying ◽  
Externally Bonded

Fiber reinforced cementitious matrix (FRCM) composites have recently become a hot topic in Europe as an alternative to traditional fiber reinforced polymer (FRP) composites for several strengthening applications of existing masonry buildings. The terrific success of this new retrofitting system is mainly due to some advantages that it offers when compared to FRP, such as the possibility of application of the composite to wet surfaces and the vapor permeability featured by the inorganic matrix. In this work, the stress transfer between FRCM composites and a masonry substrate is investigated. FRCM strips comprised of ultra-high-strength steel fibers embedded in a cementitious grout are externally bonded to masonry blocks. Single-lap direct shear tests are performed. Parameters studied are bonded length and density of the steel fibers. Load responses are presented and failure modes are discussed. Change in the bond behavior and load carrying capacity with increasing bonded length is analyzed to determine the effective bond length.

Experimental Analysis of the Bond Behavior of Glass, Carbon, and Steel FRCM Composites

2014 ◽  
Vol 624 ◽  
pp. 371-378 ◽  
Author(s):  
Tommaso D'Antino ◽  
Carlo Pellegrino ◽  
Christian Carloni ◽  
Lesley H. Sneed ◽  
Giorgio Giacomin
Keyword(s):  
Stress Transfer ◽  
High Strength ◽  
Fiber Reinforced ◽  
Bond Behavior ◽  
Cementitious Matrix ◽  
Frp Composites ◽  
Reinforced Polymer ◽  
The Matrix ◽  
Glass Carbon ◽  
Concrete Matrix

In recent decades, the construction industry has witnessed a rapid growth of interest in strengthening and retrofitting of existing reinforced concrete (RC) and masonry structures. Fiber reinforced polymer (FRP) composites have gained great popularity, and several studies are now available in the literature on their use in strengthening and retrofit applications. Promising newly-developed composite materials are represented by the so-called fiber reinforced cementitious matrix (FRCM) composites. FRCM composites are comprised of high strength fibers embedded within a cementitious matrix that is responsible for the stress transfer between the existing structure and the strengthening material. FRCM composites are still in their infancy, and very limited results are available in the literature on RC and masonry strengthening applications. This study presents an experimental campaign conducted on different FRCM composites comprised of glass, carbon, or steel fibers embedded within two different cementitious matrices and applied to concrete prisms. The single-lap direct-shear test was used to study the stress-transfer mechanism between the FRCM composite and the concrete substrate. Two different composite bonded lengths were investigated. Debonding occurred at the matrix-fiber interface for some of the composites tested and at the concrete-matrix interface for others. This work contributes to the study of the bond behavior of FRCM composites, which represents a key issue for the effectiveness of FRCM composite strengthening.

A New Pull-Out Test to Study the Bond Behavior of Fiber Reinforced Cementitious Composites

2017 ◽  
Vol 747 ◽  
pp. 258-265 ◽  
Author(s):  
Tommaso D'Antino ◽  
Francesca Giulia Carozzi ◽  
Pierluigi Colombi ◽  
Carlo Poggi
Keyword(s):  
Stress Transfer ◽  
High Strength ◽  
Fiber Reinforced ◽  
Bond Behavior ◽  
Direct Shear Tests ◽  
Pull Out ◽  
The Matrix ◽  
Set Up ◽  
High Strength Fiber ◽  
Fiber Reinforced Cementitious Composites

Fiber reinforced cementitious matrix (FRCM) composites are gaining increasing popularity in the civil engineering community. FRCM composites are comprised of high-strength fiber textiles embedded within inorganic matrices that are responsible for the stress-transfer mechanism between the composite and the substrate. Failure of FRCM composites including one layer of textile is generally reported to be debonding of the fibers from the embedding matrix. Therefore, the bond behavior of the matrix-fiber interface is of critical importance for these types of composites.This paper presents the results of an experimental campaign carried out to investigate the bond behavior of an FRCM composite comprising PBO fibers. Specimens were tested using a newly-developed pull-out test set-up. The results obtained are compared with those obtained by different authors on single-lap direct-shear tests with the same FRCM composite.

Experimental Investigation of Glass and Carbon FRCM Composite Materials Applied onto Concrete Supports

2016 ◽  
Vol 847 ◽  
pp. 60-67 ◽  
Author(s):  
Tommaso D'Antino ◽  
Jaime Gonzalez ◽  
Carlo Pellegrino ◽  
Christian Carloni ◽  
Lesley H. Sneed
Keyword(s):  
High Strength ◽  
Shear Strengthening ◽  
Existing Structures ◽  
Direct Shear Tests ◽  
Frp Composites ◽  
Load Response ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Concrete Joints ◽  
Fibre Reinforced Composites

In recent decades the growing need for strengthening and retrofitting existing structures has led to the development of innovative strengthening materials. Fibre reinforced composites have been shown to be an effective strengthening solution for flexural and shear strengthening and for confinement of axially/eccentrically loaded elements. Fibre Reinforced Cementitious Matrix (FRCM) composites, comprised of high-strength fibres and an inorganic matrix, are a newly-developed type of composite that has better resistance to high temperature and compatibility with the substrate than traditional fibre reinforced polymer (FRP) composites. This paper investigates the behaviour of FRCM composites comprised of a glass or carbon fibre net tested using single-lap direct-shear tests. Observations regarding the load response and failure mode of FRCM-concrete joints with different geometrical and mechanical characteristics are provided.

INTERFACIAL AND TENSILE PROPERTIES OF HYBRID FRP COMPOSITES USING DNN STRUCTURE WITH OPTIMIZATION MODEL

2019 ◽  
Vol 27 (02) ◽  
pp. 1950099 ◽  
Author(s):  
AHMED ABDUL BASEER ◽  
D. V. RAVI SHANKAR ◽  
M. MANZOOR HUSSAIN
Keyword(s):  
Tensile Properties ◽  
Natural Fiber ◽  
Hybrid Composites ◽  
Research Work ◽  
Composite Plates ◽  
High Strength ◽  
Fiber Reinforced ◽  
Reinforced Concrete Structure ◽  
Shear Strengthening ◽  
Frp Composites

Fiber reinforced polymer (FRP) composites are appealing for use in structural building applications because of their high strength-to-weight and stiffness-to-weight proportions, corrosion resistance, lightweight, possibly high durability, along with free design characteristics. The aim of this research work was to develop high strength natural fiber-based composite plates for the possible application in the shear strengthening of the reinforced concrete structure. In the experimental modeling, the composites were fabricated using glass, flax and kenaf fibers in treated and untreated conditions. This paper studied and analyzed the interfacial and tensile properties of fiber reinforced hybrid composites such as flax/glass and kenaf/glass by using the simulation approach, i.e. Deep Neural Network (DNN) with weight optimization. For optimizing the weights in DNN, Oppositional based FireFly Optimization (OFFO) is proposed. All the optimal results exhibit in the way that the accomplished error values between the output of the experimental values and the predicted qualities are firmly equivalent to zero in the designed system.

A Study of the Fracture Process at the FRP-Masonry Interface: The Role of the Periodic Pattern of Bricks and Mortar Joints

2014 ◽  
Vol 624 ◽  
pp. 611-618 ◽  
Author(s):  
Francesco Focacci ◽  
Christian Carloni
Keyword(s):  
Axial Strain ◽  
Interfacial Shear Stress ◽  
Stress Transfer ◽  
Effective Length ◽  
Periodic Pattern ◽  
Frp Composites ◽  
Load Response ◽  
Reinforced Polymer ◽  
Load Carrying

This paper sheds light into the effect of the periodic pattern of bricks and mortar joints on the load-carrying capacity of the interface between fiber-reinforced polymer (FRP) composites and masonry. Two simplified cohesive material laws are proposed for the FRP-mortar and FRP-brick interfaces, which allow for the computation in closed form of a finite effective bond length Leff of the interfaces. The aforementioned simplified interfacial laws are employed to compute the load response of the FRP-masonry interface, and to obtain the interfacial shear stress, the FRP axial strain, and the slip profiles along the bonded length. The results indicate that length of the stress-transfer zone (LSTZ) of the FRP-masonry interface varies periodically as its location shifts with respect to the position of the mortar joints. Furthermore LSTZ can be different from the effective length of the FRP-brick interface and is influenced by the size of the bricks and mortar joints.

scholarly journals The Use of Fiber-Reinforced Polymers in Wildlife Crossing Infrastructure

2020 ◽  
Vol 12 (4) ◽  
pp. 1557 ◽  
Author(s):  
Matthew Bell ◽  
Damon Fick ◽  
Rob Ament ◽  
Nina-Marie Lister
Keyword(s):  
Glass Fibers ◽  
Weight Ratio ◽  
High Strength ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Frp Composites ◽  
Crossing Structures ◽  
Long Duration ◽  
Animal Safety ◽  
Large Animals

The proven effectiveness of highway crossing infrastructure to mitigate wildlife-vehicle collisions with large animals has made it a preferred method for increasing motorist and animal safety along road networks around the world. The crossing structures also provide safe passage for small- and medium-sized wildlife. Current methods to build these structures use concrete and steel, which often result in high costs due to the long duration of construction and the heavy machinery required to assemble the materials. Recently, engineers and architects are finding new applications of fiber-reinforced polymer (FRP) composites, due to their high strength-to-weight ratio and low life-cycle costs. This material is better suited to withstand environmental elements and the static and dynamic loads required of wildlife infrastructure. Although carbon and glass fibers along with new synthetic resins are most commonly used, current research suggests an increasing incorporation and use of bio-based and recycled materials. Since FRP bridges are corrosion resistant and hold their structural properties over time, owners of the bridge can benefit by reducing costly and time-consuming maintenance over its lifetime. Adapting FRP bridges for use as wildlife crossing structures can contribute to the long-term goals of improving motorist and passenger safety, conserving wildlife and increasing cost efficiency, while at the same time reducing plastics in landfills.

Confinement of Masonry Columns with Steel and Basalt FRCM Composites

2017 ◽  
Vol 747 ◽  
pp. 342-349 ◽  
Author(s):  
Mattia Santandrea ◽  
Giovanni Quartarone ◽  
Christian Carloni ◽  
Xiang Lin Gu
Keyword(s):  
Compressive Load ◽  
Basalt Fiber ◽  
High Strength ◽  
Fiber Reinforced Polymer ◽  
Vapor Permeability ◽  
Fiber Reinforced ◽  
Promising Alternative ◽  
Frp Composites ◽  
Reinforced Polymer ◽  
Externally Bonded

The rehabilitation of existing masonry elements by means of jacketing of columns using composite materials is becoming a remarkable technique in several applications that aim to increase the strength of existing masonry buildings. Fiber reinforced cementitious matrix (FRCM) composites are a newly developed strengthening system that consist of high-strength fibers embedded in a cementitious grout and externally bonded to the substrate. High resistance to fire and high temperatures, ease of handling during application, and vapor permeability with the substrate are some of the characteristics that make FRCMs a promising alternative to traditional organic composites such as fiber reinforced polymer (FRP) composites. This work presents the results of an experimental study carried out to understand the behavior of masonry columns with a square cross-section confined by steel and basalt fiber sheets embedded in a mortar matrix subjected to monotonic concentric compressive load. The effectiveness of the confinement is studied in terms of load-bearing capacity with respect to unconfined columns. The effect of corner radius for columns confined with basalt fibers is investigated.

scholarly journals Numerical Evaluation of Reinforced Concrete Columns Retrofitted with FRP for Blast Mitigation

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jing Dong ◽  
Junhai Zhao ◽  
Dongfang Zhang
Keyword(s):  
High Strength ◽  
Element Model ◽  
Blast Mitigation ◽  
Rc Columns ◽  
Existing Structures ◽  
Frp Composites ◽  
Blast Response ◽  
Proposed Model ◽  
Comprehensive Comparison ◽  
Result Analysis

Fiber reinforced polymer (FRP) material is commonly applied in retrofitting structures due to the advantages of high strength and well corrosion resistance. Previous studies indicated that retrofitting with FRP sheet was an effective way for protecting the existing structures to resist the blast loads, but little research made comprehensive comparison study on the blast response of RC columns with different retrofitting strategies. This paper proposed a series of FRP retrofitting strategies and evaluated their effect on blast mitigation using numerical analysis approach. Comparison studies were conducted on the effect of FRP type, FRP thickness, and retrofitting mode on blast mitigation. A finite element model of RC columns retrofitted with FRP under blast loading was developed. The model considered the strain rate effect of steel and concrete and the orthotropic property of FRP composites. The reliability of the proposed model was validated against the data from a field blast test. Based on the verified model, the blast responses of RC columns with different retrofitting strategies were numerically investigated. According to the result analysis, appropriate FRP type, FRP thickness, retrofitting mode, and retrofitting length were recommended.

A NEW METHOD FOR STRENGTHENG CONCRETE STRUCTURES USING PRESTRESSED FRP LAMINATES

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Reza Haghani ◽  
Mohammad Al-Emrani ◽  
Robert Kliger
Keyword(s):  
Adhesive Bonding ◽  
High Strength ◽  
Bond Line ◽  
New Method ◽  
Structural Members ◽  
Interfacial Stresses ◽  
Suitable Alternative ◽  
Frp Composites ◽  
Economic Method ◽  
Strength And Stiffness

Using bonded fiber reinforced polymer (FRP) laminates for strengthening and repair of structural members has been proven to be an effective and economic method. High strength and stiffness, light weight and good fatigue and durability properties of FRP composites together with advantages offered by adhesive bonding have made it a suitable alternative for traditional strengthening and repair techniques. It has also been recognized that pre-stressing the FRP laminates prior to bonding would bring additional advantages such as reduced crack widths, postponing the yielding in tensile reinforcement, increasing the load bearing capacity and saving reinforcement material. Using pre-stressed laminates, however, is associated with very high interfacial stresses in the bond line at the laminate ends, which necessitates the use of mechanical anchors. This paper presents a new method and a device for applying pre-stressed FRP laminates to flexural structural members without the need for mechanical anchorage of the laminates. The principle of the method is based on controlling the interfacial stresses in the bond line using a non-uniform pre-stressing force profile. The principle of the method along with lab verifications and field applications are presented and discussed.

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