Proof of concept investigation of unbonded reinforcement in concrete block masonry

The use of grout in conventional reinforced masonry construction increases the cost and time of construction but allows walls subject to out-of-plane loads an enhanced ability to span between lateral support levels. An experimental investigation including a total of 21 walls was conducted in an attempt to identify potential alternatives to conventionally grouted walls. The strength and serviceability of walls containing unbonded reinforcement anchored at its ends was evaluated. All walls were two and a half blocks wide and 14 courses tall and were constructed in running bond using standard 200 mm concrete blocks. Six replicate unreinforced and partially grouted, conventionally reinforced walls served as control specimens. Walls with unbonded reinforcement were determined to be inherently stable with maximum loads approaching those of partially grouted, conventionally reinforced walls. If used in practice, these walls would need to be limited to indoor exposures due to the wide crack widths that develop.

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Experimental investigation on interlocking concrete block for masonry wall of non-engineered earthquake resistant buildings

E3S Web of Conferences ◽

10.1051/e3sconf/202015605016 ◽

2020 ◽

Vol 156 ◽

pp. 05016

Author(s):

Mochamad Teguh ◽

Furqon Widi Rivai ◽

Novi Rahmyanti ◽

Erik Wahyu Pradana

Keyword(s):

Experimental Investigation ◽

Concrete Block ◽

Seismic Damage ◽

Masonry Wall ◽

Frame Structure ◽

Clay Bricks ◽

Earthquake Resistant ◽

Out Of Plane ◽

Concrete Blocks ◽

Earthquake Load

Most of the seismic damage of existing traditional buildings is due to the absence of practical beam and column structures as the main reinforcement of the building. While a masonry wall as a structural component is commonly negligible due to their relatively low strength in contributing to the frame structure. As a result, when the earthquake struck, the building collapsed, and the ruins of building elements hit the occupants seriously and caused many deaths. This paper presents the results of preliminary research on the experimental investigation of interlocking concrete block for the masonry wall applied to non-engineered earthquake-resistant buildings. The interlocking between concrete blocks is expected to contribute to the strength of the masonry wall in resisting the loads, either in-plane or out-of-plane directions. The novelty of this type of concrete block lies in the uniqueness of the interlocking shape, making it effective in withstanding the earthquake load. This research focuses on the testing of interlocking concrete block units in withstanding loads in the direction and perpendicular to the field and equipped with testing the compressive strength of the wall and diagonal shear strength. The results produce interlocking models of concrete block contribute to better strength than ordinary clay bricks for the masonry wall.

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

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2015.228 ◽

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.

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.881.149 ◽

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.

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Study of brazilian structural concrete block conformity

Revista IBRACON de Estruturas e Materiais ◽

10.1590/s1983-41952018000400002 ◽

2018 ◽

Vol 11 (4) ◽

pp. 652-672

Author(s):

W. C. SANTIAGO ◽

A. T. BECK

Keyword(s):

Compressive Strength ◽

Dimensional Analysis ◽

Concrete Block ◽

Structural Concrete ◽

Class A ◽

Masonry Construction ◽

Strength Tests ◽

Concrete Blocks

Abstract This paper presents a study of the conformity of structural concrete blocks manufactured and used in masonry construction in Brazil. It is based on compressive strength tests, on dimensional analysis and absorption tests of over six thousand samples from three classes (A, B and C) and two modular sizes (M-15 and M-20). National results show that blocks tend to have an estimated compressive strength higher than specified, except blocks from class A. Regional results show that blocks manufactured in the northeast (NE) are consistently non-conforming, for all block classes. The study also shows that dimensional variations and absorption tests results are within code tolerances.

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

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2018-0210 ◽

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.

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Out-of-plane flexural testing and stiffness response of concrete masonry walls with NSM steel reinforcement

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2019-0685 ◽

2020 ◽

Author(s):

Adrien Sparling ◽

Dan Palermo ◽

Fariborz Hashemian

Keyword(s):

Steel Reinforcement ◽

Masonry Walls ◽

Flexural Stiffness ◽

Design Standards ◽

Near Surface ◽

Masonry Construction ◽

Flexural Testing ◽

Out Of Plane ◽

Concrete Blocks ◽

Plane Flexure

Near-surface mounted (NSM) reinforcement is used to retrofit masonry structures for increased strength and resiliency; however, its application to new masonry construction remains largely unexplored. Four masonry walls measuring 3.2m tall were constructed from hollow concrete blocks to assess the potential of NSM reinforcement to increase flexural stiffness. Two of the walls were reinforced conventionally, and two were reinforced with NSM bars. Each wall had a total area of steel reinforcement of 600mm2 and was loaded under conditions of third-point out-of-plane flexure. All four walls had similar flexural strength, ranging from 24kNm to 26kNm; however, the stiffness (determined using direct measurement of curvature, curvature calculated using conditions of equilibrium and compatibility, and the load displacement response) of the NSM reinforced walls was twice that of the walls with conventional reinforcement. The flexural stiffness of the masonry walls was underestimated by current Canadian design standards provisions under low out-of-plane loads.

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Assessment of the Flexural Behavior of Concrete Block Masonry Beams

Materials Science Forum ◽

10.4028/www.scientific.net/msf.636-637.1313 ◽

2010 ◽

Vol 636-637 ◽

pp. 1313-1320 ◽

Cited By ~ 1

Author(s):

V.G. Haach ◽

G. Vasconcelos ◽

Paulo B. Lourenço

Keyword(s):

Concrete Block ◽

Reinforced Concrete Beams ◽

Flexural Behavior ◽

Loading Test ◽

Test Configuration ◽

Reinforced Masonry ◽

Concrete Blocks ◽

Parallel Direction ◽

Flexure Capacity

This paper focus on the experimental flexural behavior of masonry beams. In the sequence of the development of a novel structural solution for reinforced masonry walls at University of Minho, different possibilities for the construction of lintels with concrete block masonry have been tested. Reinforced concrete beams with three and two hollow cell concrete blocks and with different reinforcement ratios have been built and tested in a four point loading test configuration. It was clear that horizontal bed joint reinforcement increased the ultimate flexure capacity as well as the ultimate deflection, leading to much more ductile responses. Moreover, it was also clear that a more deep analysis should be made regarding the role of the compressive strength of masonry in the parallel direction to the bed joints on the global behavior of the masonry beams.

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THIN LAYER CONCRETE BLOCKWORK IN COMPRESSION: AN EXPERIMENTAL ANALYSIS

Engineering Structures and Technologies ◽

10.3846/2029882x.2015.1115377 ◽

2015 ◽

Vol 7 (2) ◽

pp. 91-96 ◽

Cited By ~ 1

Author(s):

Ayman Trad ◽

Hassan Ghanem ◽

Nivine Abbas ◽

Ziad Hamdan

Keyword(s):

Compressive Strength ◽

Research Program ◽

Concrete Block ◽

Thin Layers ◽

Lightweight Aggregates ◽

Masonry Construction ◽

Concrete Masonry ◽

Concrete Blocks ◽

Compressive Strength Of Concrete ◽

Set Up

The compressive strength of concrete block masonry is dependent upon the unit compressive strength, the type of unit, the mortar and the form of masonry construction (Mirza et al. 1995). The design codes allow masonry compressive strength to be established (or better: estimated) by calculation, from tests, or from tabulated values. In this way the current European masonry standard EN 1996: Part 1-1 (LST EN 1996-1-1) tabulates the masonry strength for concrete blocks with thin layers of mortar. In France, doubts exist on the validity of these tabulated values for the blocks made with lightweight aggregates. To provide data for an extension of the use of the tabulated values for lightweight aggregates blocks and at the same time to provide input to the development of Eurocode 6, a major research program was set up. The research program aims to evaluate the mechanical strength of the thin joints hollow concrete masonry made with dense or lightweight aggregates. Tests have been carried out on a very large type of hollow blocks. Different geometries of blocks and different types of aggregates are tested. All these tests are based on CEN standards to meet Eurocode 6 requirements. This work proves that the formula proposed by Eurocode 6 to calculate the characteristic compressive strength of hollow concrete masonry are largely safe. It was also found that the strength of masonry depends only on the block resistance and is independent of the nature of aggregate.

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Bar size factors for lap splices in block walls subjected to flexure

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2015-0024 ◽

2015 ◽

Vol 42 (8) ◽

pp. 521-529

Author(s):

Roanne D. Kelln ◽

Lisa R. Feldman

Keyword(s):

Experimental Investigation ◽

Test Data ◽

Concrete Block ◽

Masonry Walls ◽

Reinforcing Bars ◽

Bond Failure ◽

Lap Splices ◽

Lap Splice ◽

Out Of Plane

An experimental investigation was conducted to evaluate bar size factors used for the calculation of required lap splice lengths according to US and Canadian codes for concrete block masonry walls subjected to out-of-plane loads. Wall splice specimens were constructed in running bond with all cells fully grouted, and were tested under monotonically increasing four-point loading. Specimens were longitudinally reinforced with either No. 15, 20, or 25 reinforcing bars with varying lap splice lengths that were sufficiently short to ensure that a bond failure would precede a failure in flexure. Modifications to the bar size factors included in both codes were derived from the resulting test data. The evaluation of the test data shows that decreases to lap splice lengths could be considered for walls subjected to out-of-plane loads, which would facilitate construction.

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