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.

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.

Out-of-Plane Behavior of Masonry Walls Strengthened with Ferrocement

2010 ◽  
Vol 163-167 ◽  
pp. 3545-3550 ◽  
Author(s):  
Sheng Ping Chen
Keyword(s):  
Volume Fraction ◽  
Load Capacity ◽  
Experimental Studies ◽  
Material Model ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Ultimate Load Capacity ◽  
Softening Behavior ◽  
Reinforced Masonry ◽  
Out Of Plane

Un-reinforced masonry (URM) structures may fail and collapse under out-of-plane loads generated by seismic forces or explosions. Adding a ferrocement overlay onto the URM walls is an effective solution in increasing the ultimate load capacity and ductility. This paper deals with the numerical and experimental studies on the out-of-plane behavior of un-reinforced masonry walls strengthened with ferrocement. The material parameters considered are the volume fraction of reinforcement and the loading area. A numerical model was proposed to simulate the experimental results. The employed material model for masonry wall is based on the theory of Drucker-Prager plasticity taking into account the tension softening behavior, while the ferrocement is modeled as a composite material with linear strain hardening followed by ideal plasticity. The proposed model simulates the load-deflection behavior of the strengthened wall well.

Experimental study of reinforced masonry walls subjected to combined axial load and out-of-plane bendingThis article is one of a selection of papers published in this Special Issue on Masonry.

2007 ◽  
Vol 34 (11) ◽  
pp. 1486-1494 ◽  
Author(s):  
Y. Liu ◽  
K. Hu
Keyword(s):  
Slenderness Ratio ◽  
Compressive Loading ◽  
Masonry Wall ◽  
Test Results ◽  
Secondary Effects ◽  
Reinforced Masonry ◽  
Out Of Plane ◽  
Support Conditions ◽  
The Moment ◽  
Type Of Failure

Twelve reinforced masonry wall specimens with nominal dimensions of 2400 mm × 800 mm × 150 mm were tested under eccentric compressive loading with varying eccentricity to thickness ratios, e/t, and end eccentricity ratios, e1/e2. Pinned-pinned support conditions resulted in a slenderness ratio of 17.1 for all specimens. Test results showed that the variation of ultimate load, Pu, and effective modulus of rigidity values, EIeff, at failure depended on the type of failure mode, which was influenced by e/t and e1/e2 ratios and their interaction. Comparing ultimate loads obtained by test against those calculated using the EIeff values from the Canadian standard CSA S304.1-04 and against the ones calculated using the EIeff values proposed herein indicates that, while the moment magnifier method used in the current Canadian design standard to account for secondary effects is effective, the standard underestimates EIeff values, especially in regions where compression-controlled failure tends to predominate and, thus, leads to a conservative design. However, the use of proposed EIeff values in combination with the moment magnifier method provides estimations of ultimate loads in reasonably good agreement with test results.

Numerical study of composite material (FRP/TRC)-reinforced masonry walls under in-plane loading

2021 ◽  
pp. 002199832110152
Author(s):  
Thi-Loan Bui ◽  
Zakaria Ilyes Djamai ◽  
A Si Larbi ◽  
N Reboul ◽  
E Ferrier
Keyword(s):  
Numerical Study ◽  
Concrete Block ◽  
Masonry Wall ◽  
Efficiency Factor ◽  
Elastic Behaviour ◽  
Uniaxial Tensile ◽  
Axial Stiffness ◽  
Masonry Walls ◽  
Global Factor ◽  
Reinforced Masonry

Fibre-reinforced polymers (FRPs) and textile-reinforced concretes (TRCs) are becoming increasingly common solutions for strengthening masonry walls. This study focuses on different approaches for modelling the behaviour of hollow concrete block masonry walls strengthened with FRPs and a TRC subjected to in-plane loading. Specifically, the masonry is modelled using the heterogeneous approach, wherein the damage post-peak softening behaviours of both bricks and mortar are considered, as this approach is appropriate for material and structure scales. To model the FRP/TRC-reinforced masonry walls, the reinforcements (FRPs/TRC) are perfectly connected to the substrate. Although the homogeneous approach is proposed to model the FRPs with linear elastic behaviour and is shown to be appropriate for modelling the FRP-reinforced masonry walls, the TRC is modelled using the heterogeneous approach, allowing for the real contribution of the filaments to be expressed through an ‘efficiency factor’. The numerical results show that this factor has a significant influence on the behaviour of the TRC and therefore, on the overall behaviour of the TRC-reinforced walls. However, the ‘efficiency factor’ of the TRC sample is significantly higher than that of the TRC in the strengthened wall. This result confirms that the choice of the heterogeneous approach to model the TRC in our case is appropriate. Moreover, it verifies that it is impossible to transpose this global factor from the material scale (uniaxial tensile stress) to the structure scale when the application target is a masonry wall (multi-axiality, and therefore, complexity of the stress). Consequently, the constitutive laws of the TRC composite obtained through only direct uniaxial tensile characterization procedures are insufficient to enable a suitable restitution of the overall behaviour of the masonry reinforced with the TRC. In addition, regardless of the nature of the reinforcement, the overall behaviours of the masonry walls reinforced with the FRPs/TRC are governed by both the axial stiffness of the reinforcement and the compressive strength of the masonry substrate.

INFLUENCE OF NEAR-SURFACE MOUNTED FRP WITH CEMENTITIOUS MATERIAL ON OUT-OF-PLANE BEHAVIOR OF REINFORCED MASONRY WALLS

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Zuhair Aljaberi ◽  
John J. Myers
Keyword(s):  
Concrete Block ◽  
Cementitious Material ◽  
Masonry Walls ◽  
Near Surface ◽  
Modes Of Failure ◽  
Reinforced Walls ◽  
Reinforced Masonry ◽  
Out Of Plane ◽  
Near Surface Mounted ◽  
Frp Bars

Eight medium scale reinforced masonry walls were built as a part of this study. These reinforced walls were strengthened using carbon fiber reinforced polymer [FRP] (bars and tapes) and glass FRP (bars) using a near surface mounted technique (NSM) with cementitious material; constant mild steel reinforcement ratio (ρ) was used. These strengthened walls were supported as a simply supported wall under an out-of-plane cyclic load applied along two line loads. This study presented the effect of different parameters, these parameters related to FRP (type and amount), bond pattern (stack and running), and existing of FRP in compression face of the walls. This paper reveals the relation between these factors and the out-of-plane capacity of the reinforced wall strengthened with FRP. Different modes of failure occurred in the strengthened reinforced walls, including a punching shear failure through the concrete block, crushing of concrete block and debonding of FRP reinforcement from the masonry substrate.

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 and Numerical Study of Behaviour of Reinforced Masonry Walls with NSM CFRP Strips Subjected to Combined Loads

Buildings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 103
Author(s):  
Houria Hernoune ◽  
Benchaa Benabed ◽  
Antonios Kanellopoulos ◽  
Alaa Hussein Al-Zuhairi ◽  
Abdelhamid Guettala
Keyword(s):  
Failure Modes ◽  
Numerical Study ◽  
Masonry Wall ◽  
Brick Masonry ◽  
Masonry Walls ◽  
Near Surface ◽  
Combined Loads ◽  
Reinforced Masonry ◽  
Brick And Mortar ◽  
Near Surface Mounted

Near surface mounted (NSM) carbon fibers reinforced polymer (CFRP) reinforcement is one of the techniques for reinforcing masonry structures and is considered to provide significant advantages. This paper is composed of two parts. The first part presents the experimental study of brick masonry walls reinforced with NSM CFRP strips under combined shear-compression loads. Masonry walls have been tested under vertical compression, with different bed joint orientations 90° and 45° relative to the loading direction. Different reinforcement orientations were used including vertical, horizontal, and a combination of both sides of the wall. The second part of this paper comprises a numerical analysis of unreinforced brick masonry (URM) walls using the detailed micro-modelling approach (DMM) by means of ABAQUS software. In this analysis, the non-linearity behavior of brick and mortar was simulated using the concrete damaged plasticity (CDP) constitutive laws. The results proved that the application of the NSM-CFRP strips on the masonry wall influences significantly strength, ductility, and post-peak behavior, as well as changing the failure modes. The adopted DMM model provides a good interface to predict the post peak behavior and failure mode of unreinforced brick masonry walls.

On the out-of-plane flexural design of reinforced masonry walls

2020 ◽  
Vol 27 ◽  
pp. 100945 ◽  
Author(s):  
Sarkar Noor-E-Khuda ◽  
Manicka Dhanasekar
Keyword(s):  
Masonry Walls ◽  
Reinforced Masonry ◽  
Out Of Plane
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