scholarly journals Masonry Walls Retrofitted with Vertical FRP Rebars

Buildings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 72
Author(s):  
Simona Coccia ◽  
Fabio Di Carlo ◽  
Stefania Imperatore
Keyword(s):  
Ad Hoc ◽  
Masonry Wall ◽  
Seismic Retrofitting ◽  
Masonry Walls ◽  
Seismic Capacity ◽  
Seismic Behaviour ◽  
Safety Level ◽  
Dynamic Analyses ◽  
Out Of Plane ◽  
Vertical Bars

The out-of-plane behaviour of the walls as a consequence of an earthquake is the main vulnerability of existing masonry structures. In the case of rigid in compression not tensile resistant material, incremental dynamic analyses may be employed to evaluate the effective strength of a rocking element. When the seismic capacity of the wall is inadequate, retrofit interventions are required to assure an acceptable safety level. Conventional seismic retrofitting techniques on masonry walls influence the seismic performance of the element, which typically is modified in an out-of-plane bending behaviour. In this paper, analytical investigations are presented to investigate the possibility of a seismic retrofitting intervention able to increase the seismic strength of the wall without modifying its seismic behaviour. The analysed retrofitting technique consists in the application of composite vertical bars either in the middle section of the wall or at its external surfaces. The seismic behaviour of the retrofitted masonry wall is analytically evaluated by means of a parametric incremental dynamic analysis, carried out with an ad hoc in-house software. The effectiveness of the intervention is analysed in terms of level of seismic improvement, defined as the ratio between the seismic capacity of the reinforced and unreinforced walls.

scholarly journals Attaining a Beam-Like Behavior with FRP Strips and CAM Ribbons

2018 ◽  
Vol 2 (3) ◽  
pp. 6-16 ◽  
Author(s):  
Elena Ferretti
Keyword(s):  
Ultimate Load ◽  
Masonry Wall ◽  
Experimental Results ◽  
Seismic Retrofitting ◽  
Masonry Walls ◽  
Less Invasive ◽  
Entire Height ◽  
Out Of Plane ◽  
Seismic Forces ◽  
Frp Strips

Abstract One of the major concerns in the seismic retrofitting of masonry walls is that of increasing the ultimate load for out-of-plane forces. In multi-story buildings, these forces may originate from the hammering actions of floors, when the earthquake direction is orthogonal to the wall. A possibility for counteracting the out-of-plane displacements is retaining the wall by building some buttresses, that is, some beams lean against the wall and disposed vertically. Another possibility is to make the buttress in the thickness of the wall. In this second case, we must cut the wall for its entire height, realize the buttress, and restore the masonry wall around it. In both cases, the interventions are highly invasive. The first intervention also leads to increments of mass that enhance the attraction of seismic forces. The aim of this paper is to find a less invasive and lighter alternative for realizing buttresses. We proposed to use FRP strips and steel ribbons in a combined fashion, so as to realize an ideal vertical I-beam embedded into the wall, without requiring to cut the masonry. We also provided some experimental results for verifying the effectiveness of the model.

scholarly journals Attaining a Beam-Like Behavior with FRP Strips and CAM Ribbons

2018 ◽  
Vol 2 (3) ◽  
pp. 7 ◽  
Author(s):  
Elena Ferretti
Keyword(s):  
Ultimate Load ◽  
Masonry Wall ◽  
Experimental Results ◽  
Seismic Retrofitting ◽  
Masonry Walls ◽  
Less Invasive ◽  
Entire Height ◽  
Out Of Plane ◽  
Seismic Forces ◽  
Frp Strips

One of the major concerns in the seismic retrofitting of masonry walls is that of increasing the ultimate load for out-of-plane forces. In multi-story buildings, these forces may originate from the hammering actions of floors, when the earthquake direction is orthogonal to the wall. A possibility for counteracting the out-of-plane displacements is retaining the wall by building some buttresses, that is, some beams lean against the wall and disposed vertically. Another possibility is to make the buttress in the thickness of the wall. In this second case, we must cut the wall for its entire height, realize the buttress, and restore the masonry wall around it. In both cases, the interventions are highly invasive. The first intervention also leads to increments of mass that enhance the attraction of seismic forces. The aim of this paper is to find a less invasive and lighter alternative for realizing buttresses. We proposed to use FRP strips and steel ribbons in a combined fashion, so as to realize an ideal vertical I-beam embedded into the wall, without requiring to cut the masonry. We also provided some experimental results for verifying the effectiveness of the model.

Mechanical Properties of Various Models of Interlocking Concrete Blocks under In-Plane and Out-of-Plane Loads

2021 ◽  
Vol 881 ◽  
pp. 149-156
Author(s):  
Mochamad Teguh ◽  
Novi Rahmayanti ◽  
Zakki Rizal
Keyword(s):  
Mechanical Properties ◽  
Building Material ◽  
Experimental Tests ◽  
Concrete Block ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Plane Shear ◽  
Out Of Plane ◽  
Concrete Blocks ◽  
Local Materials

Building material innovations in various interlocking concrete block masonry from local materials to withstand lateral earthquake forces is an exciting issue in masonry wall research. The block hook has an advantage in the interlocking system's invention to withstand loads in the in-plane and out-of-plane orientations commonly required by the masonry walls against earthquake forces. Reviews of the investigation of in-plane and out-of-plane masonry walls have rarely been found in previous studies. In this paper, the results of a series of experimental tests with different interlocking models in resisting the simultaneous in-plane shear and out-of-plane bending actions on concrete blocks are presented. This paper presents a research investigation of various interlocking concrete blocks' mechanical properties with different hook thicknesses. Discussion of the trends mentioned above and their implications towards interlocking concrete block mechanical properties is provided.

scholarly journals Wire Ropes and CFRP Strips to Provide Masonry Walls with Out-Of-Plane Strengthening

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2712
Author(s):  
Elena Ferretti
Keyword(s):  
Steel Wire ◽  
Three Dimensional ◽  
Maximum Load ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Wire Ropes ◽  
Out Of Plane ◽  
Beam Mechanism ◽  
Combined Technique ◽  
The Ideal

The present paper deals with an improvement of the strengthening technique consisting in the combined use of straps—made of stainless steel ribbons—and CFRP (Carbon Fiber Reinforced Polymer) strips, to increase the out-of-plane ultimate load of masonry walls. The straps of both the previous and the new combined technique pass from one face to the opposite face of the masonry wall through some holes made along the thickness, giving rise to a three-dimensional net of loop-shaped straps, closed on themselves. The new technique replaces the stainless steel ribbons with steel wire ropes, which form closed loops around the masonry units and the CFRP strips as in the previous technique. A turnbuckle for each steel wire rope allows the closure of the loops and provides the desired pre-tension to the straps. The mechanical coupling—given by the frictional forces—between the straps and the CFRP strips on the two faces of the masonry wall gives rise to an I-beam behavior that forces the CFRP strips to resist the load as if they were the two flanges of the same I-beam. Even the previous combined technique exploits the ideal I-beam mechanism, but the greater stiffness of the steel wire ropes compared to the stiffness of the steel ribbons makes the constraint between the facing CFRP strips stiffer. This gives the reinforced structural element a greater stiffness and delamination load. In particular, the experimental results show that the maximum load achievable with the second combined technique is much greater than the maximum load provided by the CFRP strips. Even the ultimate displacement turns out to be increased, allowing us to state that the second combined technique improves both strength and ductility. Since the CFRP strips of the combined technique run along the vertical direction of the wall, the ideal I-beam mechanism is particularly useful to counteract the hammering action provided by the floors on the perimeter walls, during an earthquake. Lastly, when the building suffers heavy structural damage due to a strong earthquake, the box-type behavior offered by the three-dimensional net of straps prevents the building from collapsing, acting as a device for safeguarding life.

scholarly journals Experimental Analysis of Seismic Performance of Masonry Shear Wall Reinforced with PP-Band Mesh and Plastering Mortar under In-Plane Cyclic Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Qiang Zhou ◽  
Lingyu Yang ◽  
Wenyang Zhao
Keyword(s):  
Energy Dissipation ◽  
Cyclic Loading ◽  
Bearing Capacity ◽  
Low Cost ◽  
Low Frequency ◽  
Masonry Wall ◽  
Ultimate Bearing Capacity ◽  
Masonry Walls ◽  
Seismic Capacity ◽  
Energy Dissipation Capacity

Masonry structures are widely used in developing countries due to their low cost and simple construction, especially in remote areas, where there are a large number of houses without seismic measures. These buildings are prone to collapse and cause a lot of casualties, even under the action of small earthquakes. For the reinforcement of this structure, a cheap, effective, and easy-to-construct reinforcement method is urgently needed. Therefore, this article studies the reinforcement method of polypropylene bands (PP-bands). We have carried out low-frequency cyclic loading tests for two PP-band reinforced masonry walls and two compared masonry walls. We mainly studied the influence of PP-band and different compressive strengths of plastering mortar on the masonry wall’s seismic capacity. The seismic indicators mainly studied in this article include ultimate bearing capacity, energy dissipation capacity, stiffness degradation, and hysteresis characteristics. The experimental results show that the PP-band can greatly enhance the seismic capacity of the masonry wall. The ultimate bearing capacity, energy dissipation capacity, and displacement ductility of the PP-band reinforced wall are increased by 38%–48%, 22%–47%, and 138%–226%.

Pre-Tensioned Basalt Fibers Ropes Stitching for Masonry Strengthening against Vertical Bending: A First Experimental Insight

2017 ◽  
Vol 747 ◽  
pp. 119-127 ◽  
Author(s):  
Francesco Monni ◽  
Enrico Quagliarini ◽  
Stefano Lenci
Keyword(s):  
Seismic Behavior ◽  
Basalt Fiber ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Architectural Heritage ◽  
Experimental Campaign ◽  
Out Of Plane ◽  
Most Significant Change ◽  
Synthetic Adhesives ◽  
The Common

This paper presents the results of an experimental campaign aimed at improving the innovative technique of continuos basalt fiber (BF) stitching in order to repair the masonry panels damaged by seismic events or to enhance the seismic behavior of unreinforced masonry walls. The masonry panels were tested under out-of-plane actions, one of the common way of failure for masonry walls during an earthquake. The most significant change introduced respect to the system already tested in previous studies, is the presence of pre-tensioned elements and mechanical anchorage of the BF ropes, always with the end of proposing a dry retrofitting system. The results indicate the effectiveness of this, increasing the performance of masonry wall specimens under out-of-plane actions respect to the damaged and unreinforced conditions. Besides, this technique potentially appears fully sustainable, because it is cheap, compatible, reversible, fire, and chemical resistant, it improves but not replaces original materials and, finally, it does not substantially use synthetic adhesives. All these reasons make this novel application of BF ropes fully sustainable and specialized to architectural heritage restoration.

scholarly journals Double-Leaf Infill Masonry Walls Cyclic In-Plane Behaviour: Experimental and Numerical Investigation

2018 ◽  
Vol 12 (1) ◽  
pp. 35-48 ◽  
Author(s):  
André Furtado ◽  
Hugo Rodrigues ◽  
António Arêde ◽  
Humberto Varum
Keyword(s):  
Reinforced Concrete ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Initial Stiffness ◽  
Seismic Behaviour ◽  
Infill Panels ◽  
Modelling Strategies ◽  
Infill Masonry ◽  
The Individual ◽  
Modelling Approach

Background: The infill masonry walls are widely used in the construction of reinforced concrete buildings for different reasons (partition, thermal and acoustic demands). Since the ‘60s decade, one of the most common typology in the southern Europe was the double-leaf infill walls. Recent earthquake events proved that this specific typology have an important role in the seismic response of reinforced concrete structures in terms of stiffness, strength and failure mechanisms. However, modelling approaches of these specific infill panels cannot be found over the literature. Objective: Due to this, the major goal of the present manuscript is to present a simplified modelling strategy to simulate the double-leaf infill masonry walls seismic behaviour in the software OpenSees. Method: For this, two different modelling strategies were proposed, namely through a global and an individual modelling of the panels. An equivalent double-strut model was assumed and both strategies were compared and calibrated with experimental results from a full-scale in-plane test of a double-leaf infill masonry wall. Results: The numerical results obtained by each strategy are very accurate in terms of prediction of the specimen’ initial stiffness, maximum strength and strength degradation. Conclusion: From the force evolution throughout the tests, it was observed differences lower than 10%. Globally, the individual modelling approach reached better results.

MATERIAL AND OUT-OF-PLANE FLEXURAL PROPERTIES OF TRADITIONAL MASONRY WALL

2016 ◽  
Vol 3 (2) ◽  
Author(s):  
Noriko Takiyama ◽  
Akari Yamaguchi ◽  
Kohei Hara ◽  
Verdejo Juan Ramon Jimenez
Keyword(s):  
Mechanical Characteristics ◽  
Structural Characteristics ◽  
Tensile Tests ◽  
The Philippines ◽  
Masonry Wall ◽  
Flexural Properties ◽  
Masonry Walls ◽  
Out Of Plane ◽  
Material Tests ◽  
Compressive Tests

The October 2013 Earthquake hit the Bohol Island of the Philippines. Many traditional churches were damaged by the earthquake. In this study, material tests were conducted to assess the strength of the Philippines’ traditional masonry wall, which is composed of various materials. Additionally, out-of-plane flexural experiments were conducted to elucidate the mechanical characteristics of masonry walls found in traditional churches. The wall specimens used in this study were made of a variety of materials with different compositions. The major findings of this study are summarized as follows: (a) compressive tests and splitting tensile tests were conducted for various test samples having distinct compositions. For both tests, the strength of the cylinders without additional materials was greater than that with contamination, expect for those containing egg whites; (b) out-of-plane flexural experiments were conducted on four specimens to identify their structural characteristics.

Out-of-Plane Strengthening of Masonry Walls with FRCM Composite Materials

2017 ◽  
Vol 747 ◽  
pp. 158-165 ◽  
Author(s):  
Alessandro Bellini ◽  
Andrea Incerti ◽  
Claudio Mazzotti
Keyword(s):  
Composite Materials ◽  
Failure Modes ◽  
Theoretical Models ◽  
Masonry Wall ◽  
Image Correlation ◽  
Vertical Position ◽  
Masonry Walls ◽  
Out Of Plane ◽  
Set Up ◽  
Innovative Techniques

Structural strengthening by using composite materials proved to be one of the most suitable solutions for reinforcing masonry buildings. In this framework, the focus point of the presented experimental study is to evaluate the out-of-plane behaviour of masonry walls strengthened with Fiber Reinforced Cementitious Matrix (FRCM) composites when subjected to horizontal actions, by analyzing and discussing failure modes and their out-of-plane capacity. To this purpose, a new experimental set-up was developed, capable of applying an axial force and out-of-plane horizontal actions on full-scale masonry panels, placed in vertical position and subjected to a stress state similar to that present on a real masonry wall. Experimental results, obtained by using traditional and innovative techniques (such as Digital Image Correlation), will be compared with those coming from more conventional tensile and bond tests performed on FRCM coupons applied on masonry substrates, making use of simple theoretical models.

Analysis of safety of slender concrete masonry walls in relation to CSA S304-14

2019 ◽  
Vol 46 (5) ◽  
pp. 424-438
Author(s):  
Andrea C. Isfeld ◽  
Anna Louisa Müller ◽  
Mark Hagel ◽  
Nigel G. Shrive
Keyword(s):  
Concrete Block ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Effective Height ◽  
Design Standard ◽  
Euler Buckling ◽  
Concrete Masonry ◽  
Reinforced Masonry ◽  
Out Of Plane ◽  
Support Conditions

The Canadian masonry design standard appears to be overly conservative in determining the capacity of concrete block walls with slenderness ratios greater than 30. When assessing the potential for buckling of a masonry wall according to Euler buckling criteria, the effective height is determined in part from the end supports. In Euler theory only pinned, fixed and free support conditions are considered, and the Canadian standard considers the support conditions to be hinged, elastic or stiff. For a partially reinforced masonry wall a true hinged base support is expected to be difficult to achieve, as the width of the concrete block restrains rotation. The effect of the base support conditions on the deflected shape of partially grouted block walls was investigated under axial and out-of-plane loading. The results of this testing were compared with calculations based on the Canadian masonry standard. It becomes clear that the standard is overly conservative in many cases and the design of slender walls needs to be re-examined.

Sign in / Sign up

Export Citation Format

Share Document