Grout Injection Effect on the Shear Behavior of FRCM Strengthened Stone Masonry Panels

2019 ◽  
Vol 817 ◽  
pp. 552-559
Author(s):  
Francesca Ferretti ◽  
Andrea Incerti ◽  
Anna Rosa Tilocca ◽  
Claudio Mazzotti
Keyword(s):  
Shear Capacity ◽  
Stone Masonry ◽  
Masonry Structures ◽  
Compression Tests ◽  
Grout Injection ◽  
Structural Element ◽  
Diagonal Compression ◽  
Two Samples ◽  
Injection Effect

During the last decades, several seismic phenomena have shown the high vulnerability of existing stone masonry structures subject to horizontal actions. Innovative composite materials, such as Fiber Reinforced Cementitious Matrix (FRCM), can be adopted for the retrofitting of masonry structures. The use of these innovative FRCM systems is usually combined with a more traditional retrofitting technique: grout injection. It allows to restore or improve the transversal connection between wall leaves, ensuring a monolithic behavior of the structural element. The objective of this research was to analyze the effect of the quality of the grout injection on the shear response of FRCM strengthened stone masonry panels. Results from an experimental campaign, where stone masonry specimens were subject to diagonal compression tests, are therefore presented in this paper. Two samples were subject to grout injection and one of them was strengthened with Steel Reinforced Grout (SRG). Comparisons between the experimental results showed that grout injection alone, if correctly executed, could determine a significant improvement in the shear capacity of masonry panels. The application of the FRCM strengthening system could further enhance the behavior of the samples, especially influencing the failure mode. Comparisons with analytical formulations for the evaluation of the capacity of strengthened walls are also presented.

Shaking Table Tests on Multi-Leaf Stone Masonry Structures: Analysis of Stiffness Decay

2010 ◽  
Vol 133-134 ◽  
pp. 647-652 ◽  
Author(s):  
Nicola Mazzon ◽  
Cano M. Chavez ◽  
Maria Rosa Valluzzi ◽  
F. Casarin ◽  
Claudio Modena
Keyword(s):  
Dynamic Behaviour ◽  
Shaking Table ◽  
Stone Masonry ◽  
Mode Shapes ◽  
Masonry Structures ◽  
Shaking Table Tests ◽  
Grout Injection ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime ◽  
Before And After

The influence of the natural hydraulic lime-based grout on the dynamic behaviour of injected multi-leaf stone masonry elements is discussed in the paper. Shaking table experiments on two stone masonry buildings, tested before and after grout injection, have been performed. The paper focuses on the analysis of both the recorded accelerations and related displacements, at the bottom and at each further storey. This leads to evaluate the stiffness of the unstrengthened and injected structures. The input at increasing PGA allowed the stiffness decay to be studied, simulating a gradual damaging of the structures. These results were also interpreted in the light of both computed frequencies and mode shapes. Finally, the comparison among these results, obtained from all the models, allows to deepen the knowledge concerning the effects induced by the lime-based grout injection and on its capability to modify the dynamic behaviour, when intervening on a damaged (repairing) or on an undamaged (strengthening) structure.

scholarly journals Experimental study on notched connectors for glulam-lightweight concrete composite beams

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2171-2180
Author(s):  
Yuchen Jiang ◽  
Xiamin Hu ◽  
Wan Hong ◽  
Jun Zhang ◽  
Fangqian He
Keyword(s):  
Lightweight Concrete ◽  
Shear Fracture ◽  
Concrete Slab ◽  
Composite Beams ◽  
Shear Capacity ◽  
Major Influence ◽  
Structural Element ◽  
Diagonal Compression ◽  
Concrete Type ◽  
Shear Performance

A new type of structural element, the timber-concrete composite beam, exhibited excellent structural performance. The notched connector is widely used in timber-concrete composite systems as a result of its considerable shear capacity and stiffness. Six groups of push-out tests were performed to investigate the shear performance of the notched connectors for the timber-concrete composite beams, with consideration to the varying concrete types, the shear length of the timber, and whether the notch was reinforced. From the test results, the notched connectors that corresponded to the shear fracture of concrete or timber had a low shear capacity and poor ductility. Notched connectors that simultaneously failed at the concrete slab (via shear force), as well as at the lag screw reinforcement point during bending presented the greatest shear capacity. This was followed by the notched connectors that exhibited diagonal-compression failure at the concrete slab. Screw fasteners in the notch were shown to improve the strength, ductility, and post-peak behavior of the notched connectors. In addition, the concrete type, the shear length of the timber, and whether the notch was reinforced were found to have no major influence on the slip modulus of the notched connectors.

Masonry Reinforcement with IMG Composites: Experimental Investigation

2014 ◽  
Vol 624 ◽  
pp. 275-282 ◽  
Author(s):  
A. Balsamo ◽  
Ivano Iovinella ◽  
M. di Ludovico ◽  
Andrea Prota
Keyword(s):  
Experimental Tests ◽  
Shear Capacity ◽  
Fiber Reinforced Polymer ◽  
Stone Masonry ◽  
Theoretical Expression ◽  
Reinforced Polymer ◽  
Diagonal Compression ◽  
Historical Masonry ◽  
Strengthening Technique ◽  
Inorganic Matrix

The interest in strengthening of historical masonry structures is significantly grown especially to techniques which combine properties like as reversibility, compatibility, and sustainability of the intervention. Among these, a promising technique is the use of inorganic matrix grid (IMG) composites. Several experimental tests have been carried out to prove the effectiveness of this system as a strengthening solution for different masonry types. The present paper presents the original results of five tests on uncoursed stone masonry panels under diagonal compression and collect the data of previous tests carried out by the authors on other masonry typologies. The tests results on several masonry types and strengthening layouts as well as Fiber reinforced Polymer (FRP) grid and mortar types are reported and discussed. The experimental programs clearly confirmed the effectiveness of the investigated strengthening technique to increase the panels shear capacity and ductility; however, a suitable theoretical expression to quantify the benefits provided by this strengthening solution, based on the reinforcement layout and on the masonry type, is still missing. The comparative analysis of the experimental data is presented in the paper in order to clarify the benefits provided by each strengthening system.

Shear Capacity of Masonry Panels Reinforced with Inorganic Strengthening Systems

2019 ◽  
Vol 817 ◽  
pp. 486-492
Author(s):  
Marta Del Zoppo ◽  
Gennaro Maddaloni ◽  
Alberto Balsamo ◽  
Marco di Ludovico ◽  
Andrea Prota
Keyword(s):  
Composite Materials ◽  
Shear Capacity ◽  
Masonry Walls ◽  
Masonry Buildings ◽  
Compression Tests ◽  
Plane Shear ◽  
Diagonal Compression ◽  
The University ◽  
Fabric Reinforced Cementitious Matrix ◽  
Inorganic Composite

Unreinforced masonry buildings are particularly vulnerable to brittle failures during seismic events due to the poor in-plane shear capacity of masonry walls. The use of strengthening solutions with polymeric matrices is not often recommended for masonry buildings, due to breathability issues, and the adoption of inorganic matrices is sometimes considered preferable. In this paper, the use of inorganic composite materials for improving the in-plane shear capacity of tuff masonry walls is investigated. The experimental data from 83 diagonal compression tests carried out at the University of Naples Federico II in recent years have been collected and the main results are herein discussed to outline the main features of different strengthening techniques with inorganic composite materials such as Reinforced Plaster (RP), Composite Reinforced Mortar (CRM) and Fabric Reinforced Cementitious Matrix (FRCM).

scholarly journals Mechanical Properties of Low-Performance Concrete (LPC) and Shear Capacity of Old Unreinforced LPC Squat Walls

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7310
Author(s):  
Rami Eid ◽  
Avraham N. Dancygier ◽  
Ghali Jaber
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Shear Capacity ◽  
Compression Tests ◽  
Diagonal Compression ◽  
Load Carrying ◽  
Mode Of Failure ◽  
Major Principal Stress ◽  
Low Performance ◽  
Squat Walls

Low-performance concrete (LPC) is characterized by its low strength and commonly by the presence of large aggregates. This type of concrete was used for construction of load carrying, commonly unreinforced walls in old buildings. The resistance of these buildings with LPC squat walls (of relatively low height-to-length ratio), to in plane horizontal loads, was experimentally investigated in this study. The low compressive strength of these walls, well below that of standard concrete, requires estimation of the relation between the actual LPC compressive strength and its tensile strength, and identification of their failure mode and corresponding shear capacity when subjected to in plane horizontal loads. In this study, compressive and splitting tensile strengths of authentic LPC specimens were measured, and based on them, a relation between the compressive and tensile strengths is proposed. Then, diagonal compression tests were performed on authentic LPC specimens, as well as specimens made of standard concrete. These tests yielded the expected mode of failure of vertical cracking and their analysis shows that their shear capacity needs to be evaluated based on their tensile strength (rather than the flexural shear capacity of unreinforced concrete beams). Thus, the load-bearing (both horizontal and gravitational) capacity to prevent diagonal tension failure of an unreinforced LPC wall can be evaluated by comparing the LPC tensile strength to the major principal stress caused by the load. Assessment of the tensile strength can be based on the relation between the compressive and tensile strengths proposed in this work.

scholarly journals Hardening Properties of Cheeses by Latilactobacillus curvatus PD1 Isolated from Hardened Cheese-Ddukbokki Rice Cake

2021 ◽  
Vol 9 (5) ◽  
pp. 1044
Author(s):  
Jeong A Kim ◽  
Geun Su Kim ◽  
Se Mi Choi ◽  
Myeong Seon Kim ◽  
Do Young Kwon ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Acid Production ◽  
Lactobacillus Casei ◽  
Leuconostoc Mesenteroides ◽  
The Other ◽  
Rice Cake ◽  
Two Samples ◽  
High Protease Activity

Hardening of cheese is one of major issues that degrade the quality of Home Meal Replacement (HMR) foods containing cheese such as Cheese-ddukbokki rice cake (CD, stir-fried rice cakes with shredded cheese). The quality of cheese, such as pH, proteolytic, and flavor properties, depends on various lactic acid bacteria (LAB) used in cheese fermentation. The hardening of cheese is also caused by LAB. In this study, various LAB strains were isolated from CD samples that showed rapid hardening. The correlation of LAB with the hardening of cheese was investigated. Seven of the CD samples with different manufacturing dates were collected and tested for hardening properties of cheese. Among them, strong-hardening of cheese was confirmed for two samples and weak-hardening was confirmed for one sample. All LAB in two strong-hardening samples and 40% of LAB in one weak-hardening sample were identified as Latilactobacillus curvatus. On the other hand, most LAB in normal cheese samples were identified as Leuconostoc mesenteroides and Lactobacillus casei. We prepared cheese samples in which L. curvatus (LC-CD) and L. mesenteroides (LM-CD) were most dominant, respectively. Each CD made of the prepared cheese was subjected to quality test for 50 days at 10 °C. Hardening of cheese with LC-CD dominant appeared at 30 days. However, hardening of cheese with LM-CD dominant did not appear until 50 days. The pH of the LC-CD was 5.18 ± 0.04 at 30 days, lower than that of LM-CD. The proteolytic activity of LC-CD sample was 2993.67 ± 246.17 units/g, higher than that of LM-CD sample (1421.67 ± 174.5 units/g). These results indicate that high acid production and high protease activity of L. curvatus might have caused hardening of cheese.

scholarly journals The Effect of Acetic Acid Treatments on the Quality of Stored Carrot (Daucus carota L.) Seeds

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1176
Author(s):  
Hanna Dorna ◽  
Agnieszka Rosińska ◽  
Dorota Szopińska
Keyword(s):  
Acetic Acid ◽  
Distilled Water ◽  
Storage Duration ◽  
Seed Vigour ◽  
Daucus Carota L ◽  
Two Samples ◽  
Before And After ◽  
Alternaria Dauci ◽  
Acid Treatments

Alternaria dauci (J.G. Kühn) J.W. Groves et Skolko and A. radicina Meier, Drechsler et E.D. Eddy are important seed-transmitted pathogens of carrot. The aim of this study was to evaluate the effects of acetic acid treatments on the quality of stored carrot seeds. Seeds of two samples were soaked for 30 min in 0.5, 1 and 2% acetic acid. Controls included untreated seeds, seeds soaked in distilled water and seeds treated with fungicide Zaprawa Nasienna T 75 WS/DS (a.i. thiram 75%). Germination, vigour and health of untreated and treated seeds were evaluated before and after 5 and 12 months of storage at 4 and 20 °C. Seeds of both samples treated with 0.5 and 1% acetic acid were characterized by higher germination capacity after storage than untreated seeds. However, treatments with 1 and 2% acetic acid negatively affected seed vigour. Generally, seeds of both samples treated with acetic acid were characterized by lower infestation with A. alternata and A. radicina after storage than untreated seeds and seeds soaked in distilled water. Moreover, acetic acid often controlled these fungi more effectively than the fungicide. Regardless of the storage duration, infestation with fungi was higher if seeds of both samples were stored at a lower temperature.

scholarly journals In-plane Shear Strengthening of Unreinforced Masonry Walls Using GFRP Jacketing

2017 ◽  
Author(s):  
Enea Mustafaraj ◽  
Yavuz Yardim
Keyword(s):  
Experimental Results ◽  
Test Results ◽  
Compression Tests ◽  
Shear Strengthening ◽  
Plane Shear ◽  
Standard Size ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Diagonal Compression ◽  
Before And After

In this paper, it is presented the experimental results of a campaign on diagonal compression tests, as of ASTM E519-02, to assess and compare the in-plane behavior of standard size of 1200 × 1200 × 250 mm, for three unreinforced and three reinforced wall panels by glass fiber reinforced polymer (GFRP) embedded in an inorganic matrix.From the diagonal compression test results, were determined some of the main mechanical parameters such as: shear strength, modulus of rigidity and ductility, before and after application of the reinforcement.The experimental results showed that the GFRP reinforced panels exhibited a significant increase of 127% in shear resistance, 1100% in ductility and 650% in modulus of rigidity when compared to unreinforced panels.It was concluded that this technique provided satisfactory results and can be considered a suitable method for repair of masonry structures.

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