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Dr. Tatheer Zahra
School of Civil Engineering and Built Environment, Queensland University of Technology, Brisbane 4000, Australia

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0 Concrete
0 Masonry
0 3D printing
0 Auxetics
0 Mortar composites

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Mortar composites

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Journal article
Published: 06 July 2021 in Buildings
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Prefabrication has been shown to be an effective way of construction in the modern-day context. Although much progress has been made in developing reinforced concrete (RC), timber and steel prefabricated elements/structures, prefabrication of masonry walling systems has received limited attention in the past. Conventional masonry construction is labour-intensive and time-consuming; therefore, prefabrication can be an effective solution to accelerate the masonry construction to make it more cost-effective. Therefore, in this paper, an attempt has been made to evaluate the effectiveness of prefabricated masonry systems (PMS) in terms of their structural characteristics and sustainability perspectives in an Australian context. Subsequently, the available studies related to PMS and the prospects of developing prefabricated masonry walling systems were appraised and reported. In order to assess the applicability of PMS, a case study was carried out by designing four types of prospective prefabricated masonry walling systems for a typical housing unit in Australia. It was shown that the reinforced (RM), post-tensioned (PT) and thin layered mortared (TLM) masonry systems are better suited for prefabrication. Later, in order to assess the sustainability of the considered masonry walling systems, life cycle energy analyses were carried using the Environmental Performance in Construction (EPIC) database. It was found that there can be nearly 30% and 15% savings, respectively, in terms of energy saving and CO2 emissions in prefabricated construction than the conventional masonry construction. Finally, the prospects of developing PMS and the need for future research studies on these systems are highlighted.

ACS Style

Julian Thamboo; Tatheer Zahra; Satheeskumar Navaratnam; Mohammad Asad; Keerthan Poologanathan. Prospects of Developing Prefabricated Masonry Walling Systems in Australia. Buildings 2021, 11, 294 .

AMA Style

Julian Thamboo, Tatheer Zahra, Satheeskumar Navaratnam, Mohammad Asad, Keerthan Poologanathan. Prospects of Developing Prefabricated Masonry Walling Systems in Australia. Buildings. 2021; 11 (7):294.

Chicago/Turabian Style

Julian Thamboo; Tatheer Zahra; Satheeskumar Navaratnam; Mohammad Asad; Keerthan Poologanathan. 2021. "Prospects of Developing Prefabricated Masonry Walling Systems in Australia." Buildings 11, no. 7: 294.

Journal article
Published: 08 June 2021 in Construction and Building Materials
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Reinforced masonry (RM) walls are mostly used in low to mid rise residential/industrial buildings in cyclonic and seismic regions. They are conventionally constructed with grout embedded vertical steel reinforcements positioned in the middle of the hollow blocks. However, these reinforcing bars are rarely detailed with lateral restrainers, which are considered essential in the design standards to avoid buckling of the vertical bars. This research investigates the effectiveness of lateral restrainers to the axial compression resistance of RM by testing of 128 walls under concentric and eccentric compression with different reinforcement configurations. The tested walls (190 mm thick × 600 mm wide) consisted of various types of detailing with and without lateral restrainers, grout strengths (25–50 MPa), and three heights (800 mm, 1400 mm and 2400 mm). Two walls were constructed and tested for each configuration, out of which one was tested to determine the ultimate strength and the other tested to acquire ultimate strength, axial deformation of the wall, axial strain in the steel bars and strain on the surfaces of the face-shell. The experimental results revealed that the grout has significantly contributed to the axial capacity, whilst the lateral restrainer reinforcement detailing had no significant effect on either the steel strain development or on the overall strength of the RM walls. Under concentric compression, the strain measurements in the vertical steel bars indicated that irrespective of the absence or presence of the lateral restrainers, the vertical bars remained under compression throughout the loading history with no evidence of buckling. Effects of slenderness and eccentricity were also evaluated for the RM walls under compression. It can be concluded from this research that the RM walls designed and constructed without lateral restrainers to resist cyclonic and seismic forces need not be treated as unreinforced masonry (URM) for compression if the vertical bars are surrounded by well compacted grout.

ACS Style

Tatheer Zahra; Julian Thamboo; Mohammad Asad; Mengli Song. Experimental investigation on the effectiveness of lateral restrainers to the vertical steel in reinforced masonry walls under axial compression. Construction and Building Materials 2021, 297, 123790 .

AMA Style

Tatheer Zahra, Julian Thamboo, Mohammad Asad, Mengli Song. Experimental investigation on the effectiveness of lateral restrainers to the vertical steel in reinforced masonry walls under axial compression. Construction and Building Materials. 2021; 297 ():123790.

Chicago/Turabian Style

Tatheer Zahra; Julian Thamboo; Mohammad Asad; Mengli Song. 2021. "Experimental investigation on the effectiveness of lateral restrainers to the vertical steel in reinforced masonry walls under axial compression." Construction and Building Materials 297, no. : 123790.

Journal article
Published: 08 April 2021 in Structures
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Bonded brickwork walls of large thickness constructed with double or triple bricks are common in loadbearing historical masonry structures in many regions which require interventions and compression capacity evaluation. However, current design provisions for compression capacity prediction are primarily based on single brick prisms and wallette specimens. Due to anisotropic nature of masonry, the strength and deformation characteristics of bonded brickwork with double and triple brick thicknesses are different to the single leaf brickwork; and their design using the provisions of single leaf bonded brickwork specimens may be un-conservative. To expand the knowledge on the compressive behaviour of bonded brickwork, a detailed numerical investigation has been reported in this paper. A simplified Finite element (FE) based micro-modelling technique was implemented to simulate the compression response of bonded brickwork specimens. The developed FE modelling technique was initially verified against the experimental predictions of compressive capacities and axial stress-strain curves. The numerical modelling results iterated that there was no noticeable increase in the compressive capacity of the masonry with increase in the brickwork thicknesses due to increased number of weak head joints. The validated models were then employed to study the effect of slenderness of the bonded brickwork specimens on the axial compression response. The height to thickness (slenderness) ratios of the bonded brickwork were varied from 1.4 to 10.9 for analysing 30 different cases with two brick strengths. Results showed that with increasing slenderness ratio, the compressive strength of the bonded brickwork reduces for all bonded thicknesses. The parametric study indicates that the slenderness ratio influences the compression characteristics of bonded brickwork specimens; subsequently, correction factors for the compressive strengths determined with different slenderness ratios of brickwork specimens are proposed.

ACS Style

Tatheer Zahra; Mohammad Asad; Julian Thamboo. Effect of geometry on the compression characteristics of bonded brickwork. Structures 2021, 32, 1408 -1419.

AMA Style

Tatheer Zahra, Mohammad Asad, Julian Thamboo. Effect of geometry on the compression characteristics of bonded brickwork. Structures. 2021; 32 ():1408-1419.

Chicago/Turabian Style

Tatheer Zahra; Mohammad Asad; Julian Thamboo. 2021. "Effect of geometry on the compression characteristics of bonded brickwork." Structures 32, no. : 1408-1419.

Journal article
Published: 03 February 2021 in Construction and Building Materials
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This paper aims to assess the strength of a 100 + year old masonry arch bridges in Australia that are currently in operation and routinely subjected to train loadings. Towards this end, 45 cores of 150 mm diameter with varied lengths and joint configurations were drilled from a typical bridge and tested. Out of these samples, 30 were tested under direct compression and 15 were tested for tensile strength with varying bed joint angles. The samples for compression testing were regularised by developing high strength mortar capping whereas, the samples for tensile strength were tested according to Brazilian testing method commonly used for evaluating the splitting tensile strength of materials. The typical failure mode of masonry under compression was due to vertical cracking in bricks, spalling and cracking in perpend joints. The average compressive strength of masonry was determined as 10.6 MPa. Young’s modulus was also determined with a magnitude of 11,048 MPa which is comparable to an in-situ flat jack test conducted on the similar bridges. The increased number of perpend joints in masonry cores decreased the masonry compressive strength. Splitting tests revealed the average tensile strength of 1.34 MPa. From the results it can be concluded that the aged masonry used in the arch bridge has a higher strength than previously thought of and that the bridge seems to be capable of sustaining the current train loads, as observed at site.

ACS Style

Jigme Dorji; Tatheer Zahra; David Thambiratnam; Daniel Lee. Strength assessment of old masonry arch bridges through moderate destructive testing methods. Construction and Building Materials 2021, 278, 122391 .

AMA Style

Jigme Dorji, Tatheer Zahra, David Thambiratnam, Daniel Lee. Strength assessment of old masonry arch bridges through moderate destructive testing methods. Construction and Building Materials. 2021; 278 ():122391.

Chicago/Turabian Style

Jigme Dorji; Tatheer Zahra; David Thambiratnam; Daniel Lee. 2021. "Strength assessment of old masonry arch bridges through moderate destructive testing methods." Construction and Building Materials 278, no. : 122391.

Journal article
Published: 24 January 2021 in Journal of Building Engineering
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Concrete hollow block masonry is widely used in North American and Australasian countries because it enables to accommodate grouting and reinforcement to resist higher axial and lateral actions, where it ultimately facilitates to construct high-rise masonry buildings. Subsequently only certain grades of mortars are recommended for the concrete block masonry in the standards mainly due to durability concerns. However, there is a lack of knowledge on the characteristics of concrete masonry with different grades of mortars and significant variations are found among the design standards. Therefore, in this research, an attempt has been made to investigate the compressive strength and deformation characteristics of concrete block masonry using different mortar grades, mortar bedding types and block types. In total, 40 concrete block masonry prisms were constructed and tested with three different types of mortars, two mortar bedding types and two types of concrete blocks. From the experimental results, the failure modes, compressive strength and stress-strain curves are derived and discussed. The experimental results revealed that the lower grade mortared prisms failed by mortar crushing and block splitting, whereas the other mortared prisms mainly failed by tensile splitting in the blocks. The compressive strength of concrete masonry was not significantly compromised for lower grade mortared prisms in comparison to other mortared prism combinations. The deformations and failure phenomenon of the mortar joints, blocks and prisms were investigated in detail using a non-contact digital image correlation (DIC) method. The experimental results were also verified through the finite element analyses and were compared with the predictions of four different masonry design standards. Discrepancies in the prediction of compressive strengths of concrete block masonry between the design standards were noted.

ACS Style

Tatheer Zahra; Julian Thamboo; Mohammad Asad. Compressive strength and deformation characteristics of concrete block masonry made with different mortars, blocks and mortar beddings types. Journal of Building Engineering 2021, 38, 102213 .

AMA Style

Tatheer Zahra, Julian Thamboo, Mohammad Asad. Compressive strength and deformation characteristics of concrete block masonry made with different mortars, blocks and mortar beddings types. Journal of Building Engineering. 2021; 38 ():102213.

Chicago/Turabian Style

Tatheer Zahra; Julian Thamboo; Mohammad Asad. 2021. "Compressive strength and deformation characteristics of concrete block masonry made with different mortars, blocks and mortar beddings types." Journal of Building Engineering 38, no. : 102213.

Journal article
Published: 13 November 2020 in Structures
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Masonry buildings constructed along busy roads are vulnerable to vehicular impacts resulting in damage to property and harm to occupants. This paper presents two strategies that use either carbon fibre or auxetic composite render for mitigating the adverse effects of such impacts and compares the merits of the two strategies. As masonry is a relatively low strength brittle material, the rendering material should possess high energy absorption characteristics (as in auxetic composite) or high strength (as in carbon fibre composite) properties for impact damage mitigation. Towards this end, finite element models incorporating material and contact nonlinearities and (recently developed) carbon fabric and auxetic fabric composite renders possessing positive and negative Poisson’s ratios respectively are developed and applied. These models are validated using experimental datasets and then applied to masonry walls impacted laterally at velocities ranging from 6 km/h to 100 km/h. Results show that the failure mechanism of masonry walls varies from global to local with the increase in the impact velocity and that the auxetic composite render significantly minimises debonding risks, enhances energy dissipation characteristics, reduces the impact force and the impact damage on the masonry walls, compared to carbon fibre composite render.

ACS Style

Mohammad Asad; Manicka Dhanasekar; Tatheer Zahra; David Thambiratnam. Impact mitigation of masonry walls with carbon fibre and Auxetic fibre composite renders – A numerical study. Structures 2020, 28, 2733 -2751.

AMA Style

Mohammad Asad, Manicka Dhanasekar, Tatheer Zahra, David Thambiratnam. Impact mitigation of masonry walls with carbon fibre and Auxetic fibre composite renders – A numerical study. Structures. 2020; 28 ():2733-2751.

Chicago/Turabian Style

Mohammad Asad; Manicka Dhanasekar; Tatheer Zahra; David Thambiratnam. 2020. "Impact mitigation of masonry walls with carbon fibre and Auxetic fibre composite renders – A numerical study." Structures 28, no. : 2733-2751.

Journal article
Published: 16 July 2020 in Engineering Failure Analysis
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Masonry buildings constructed along busy roads are vulnerable to vehicular impacts. As most of these impacts are likely to occur at low velocity due to severe braking by drivers to avoid catastrophe, the present study reports a failure analysis of masonry walls subject to low velocity impacts. An explicit finite element modelling method incorporating homogenised anisotropic masonry material developed previously for static loading was validated through low velocity impact test datasets reported in the literature. Subsequently, an extensive study was undertaken to evaluate the impact damage patterns of masonry walls of varied boundary conditions, aspect ratios, and slenderness ratios. This paper identifies a threshold impact energy, below which contemporary single leaf masonry walls irrespective of their boundary conditions and aspect ratio, exhibit global damage with varied failure patterns. Slenderness ratio of the impacted wall is shown as the most important parameter in resisting impact loads. The results presented in this study can be useful for developing mitigation strategies for walls vulnerable to low velocity vehicular impacts.

ACS Style

Mohammad Asad; Manicka Dhanasekar; Tatheer Zahra; David Thambiratnam. Failure analysis of masonry walls subjected to low velocity impacts. Engineering Failure Analysis 2020, 116, 104706 .

AMA Style

Mohammad Asad, Manicka Dhanasekar, Tatheer Zahra, David Thambiratnam. Failure analysis of masonry walls subjected to low velocity impacts. Engineering Failure Analysis. 2020; 116 ():104706.

Chicago/Turabian Style

Mohammad Asad; Manicka Dhanasekar; Tatheer Zahra; David Thambiratnam. 2020. "Failure analysis of masonry walls subjected to low velocity impacts." Engineering Failure Analysis 116, no. : 104706.

Journal article
Published: 19 March 2020 in Construction and Building Materials
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This paper presents a concept of Interfacial Transition Zone (ITZ) enrichment for the characterisation of masonry under biaxial stress states to a nonlocal transient damage representative volume element (RVE) model developed by the authors (Jelvehpour et al., 2019). ITZ enrichment has been realised through a series of transition layers on either side of the unit – mortar interface with gradually varying properties of the constituent materials so that weaker mortar – stronger brick and stronger mortar – weaker brick combinations can be considered. Two model parameters, viz., the thickness and the stiffness degradation of the ITZ have been introduced to control the thickness and stiffness degradation of the transition layers; these parameters have been calibrated to fit the experimental data available in the literature. The calibrated ITZ enriched RVE model was then applied to conventional clay brick, concrete block and drystack (mortarless) masonry by simulating the experimental tests reported in the literature; good agreement was obtained. The RVE was then applied to predict the failure envelope of various masonry types subject to biaxial stress states. The ITZ enriched RVE eliminates the need for introduction of either interface element or contact nonlinearity between the masonry unit and the mortar or between drystack masonry units with wide ranging benefits of analysing masonry structures under various load cases.

ACS Style

Tatheer Zahra; Ali Jelvehpour; Julian A. Thamboo; Manicka Dhanasekar. Interfacial transition zone modelling for characterisation of masonry under biaxial stresses. Construction and Building Materials 2020, 249, 118735 .

AMA Style

Tatheer Zahra, Ali Jelvehpour, Julian A. Thamboo, Manicka Dhanasekar. Interfacial transition zone modelling for characterisation of masonry under biaxial stresses. Construction and Building Materials. 2020; 249 ():118735.

Chicago/Turabian Style

Tatheer Zahra; Ali Jelvehpour; Julian A. Thamboo; Manicka Dhanasekar. 2020. "Interfacial transition zone modelling for characterisation of masonry under biaxial stresses." Construction and Building Materials 249, no. : 118735.

Journal article
Published: 01 November 2019 in Construction and Building Materials
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ACS Style

Mohammad Asad; Manicka Dhanasekar; Tatheer Zahra; David Thambiratnam. Characterisation of polymer cement mortar composites containing carbon fibre or auxetic fabric overlays and inserts under flexure. Construction and Building Materials 2019, 224, 863 -879.

AMA Style

Mohammad Asad, Manicka Dhanasekar, Tatheer Zahra, David Thambiratnam. Characterisation of polymer cement mortar composites containing carbon fibre or auxetic fabric overlays and inserts under flexure. Construction and Building Materials. 2019; 224 ():863-879.

Chicago/Turabian Style

Mohammad Asad; Manicka Dhanasekar; Tatheer Zahra; David Thambiratnam. 2019. "Characterisation of polymer cement mortar composites containing carbon fibre or auxetic fabric overlays and inserts under flexure." Construction and Building Materials 224, no. : 863-879.

Short communication
Published: 03 October 2019 in Journal of Building Engineering
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As the conventional masonry construction is labour and time intensive, it faces challenges from new generation materials and construction techniques. Mortarless masonry system (MMS) is considered as an alternative to conventional masonry as it minimises skilled labour requirement and improves the construction productivity. Despite these advantages, the uptake of the MMS system is hindered by the lack of guidelines in the masonry design standards. Therefore, in this paper, an attempt has been made to extensively review the literature and develop simple design guidelines for the MMS. Primarily the methodologies have been developed to design MMS against axial compression, out-of-plane flexure and in-plane shear actions. The developed guidelines have been applied to the structural design of a conceptual MMS detached house for war affected community resettlement housing scheme in Sri Lanka. The developed design procedures reveal that the MMS can be used for loadbearing actions; however, it requires strengthening for out-of-plane flexure and in-plane shear actions against the cyclonic and seismic actions.

ACS Style

Julian Ajith Thamboo; Tatheer Zahra; Remadevi Dhanasekar. Development of design methodology for mortarless masonry system: Case study – a resettlement housing colony. Journal of Building Engineering 2019, 27, 100973 .

AMA Style

Julian Ajith Thamboo, Tatheer Zahra, Remadevi Dhanasekar. Development of design methodology for mortarless masonry system: Case study – a resettlement housing colony. Journal of Building Engineering. 2019; 27 ():100973.

Chicago/Turabian Style

Julian Ajith Thamboo; Tatheer Zahra; Remadevi Dhanasekar. 2019. "Development of design methodology for mortarless masonry system: Case study – a resettlement housing colony." Journal of Building Engineering 27, no. : 100973.

Journal article
Published: 22 May 2019 in Engineering Science and Technology, an International Journal
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Widely reported damage modelling methods inherently use elastic brittle rapidly decaying responses for materials under both uniaxial tension and compression, in spite of the existence of ample experimental evidences that the damaging process under compression is significantly different to that under tension. This paper reports a damage evolution law suitable for representing the gradual damaging under compression. Sensitivity of the parameters of the law has been systematically presented. Internal damaging process of brittle materials has been represented through increase in Poisson’s ratio, thus treating this property as a variable affected by the damage levels. These damage evolution laws have been incorporated into a diffused form of non-local transient-enhanced model and applied to the analysis of masonry through two geometrically different representative volume elements (RVE) with periodic boundary conditions. It has been shown that the geometry of the RVE is insignificant to the prediction of the stress-strain responses of masonry assemblages, thereby supporting adoption of a simple geometry of RVE for predicting the behaviour of bi-material brittle composites.

ACS Style

Ali Jelvehpour; Tatheer Zahra; Manicka Dhanasekar. A non-local transient-gradient enhanced damage modelling method incorporating variable Poisson’s ratio for brittle bi-material composites. Engineering Science and Technology, an International Journal 2019, 23, 432 -444.

AMA Style

Ali Jelvehpour, Tatheer Zahra, Manicka Dhanasekar. A non-local transient-gradient enhanced damage modelling method incorporating variable Poisson’s ratio for brittle bi-material composites. Engineering Science and Technology, an International Journal. 2019; 23 (2):432-444.

Chicago/Turabian Style

Ali Jelvehpour; Tatheer Zahra; Manicka Dhanasekar. 2019. "A non-local transient-gradient enhanced damage modelling method incorporating variable Poisson’s ratio for brittle bi-material composites." Engineering Science and Technology, an International Journal 23, no. 2: 432-444.

Journal article
Published: 01 February 2019 in Journal of Bridge Engineering
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Serviceability deflections and strains at the crown, support, and quarter point of two aged masonry arch bridges under operating passenger and freight trains were assessed using a digital image correlation method. Three lasers recorded the passage of the wheels; these data were used to ascertain the wheel positions, which corresponded well with the peaks of the deflections measured. The measured maximum deflection and strain were 0.5 mm and 110 microstrain, respectively; these data were validated through a three-dimensional (3D) finite-element model incorporating saturated soil fill, masonry arch, and their interface. The predicted strains matched well with the field measurements. The variation of the strains with the wheel positions over the arch barrel was also simulated. The magnitudes of the deflection and strain were too small to cause serviceability limit-state exceedance alarms for the masonry arches.

ACS Style

Manicka Dhanasekar; Peter Prasad; Jigme Dorji; Tatheer Zahra. Serviceability Assessment of Masonry Arch Bridges Using Digital Image Correlation. Journal of Bridge Engineering 2019, 24, 04018120 .

AMA Style

Manicka Dhanasekar, Peter Prasad, Jigme Dorji, Tatheer Zahra. Serviceability Assessment of Masonry Arch Bridges Using Digital Image Correlation. Journal of Bridge Engineering. 2019; 24 (2):04018120.

Chicago/Turabian Style

Manicka Dhanasekar; Peter Prasad; Jigme Dorji; Tatheer Zahra. 2019. "Serviceability Assessment of Masonry Arch Bridges Using Digital Image Correlation." Journal of Bridge Engineering 24, no. 2: 04018120.

Journal article
Published: 01 April 2018 in Construction and Building Materials
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ACS Style

Tatheer Zahra; Manicka Dhanasekar. Characterisation and strategies for mitigation of the contact surface unevenness in dry-stack masonry. Construction and Building Materials 2018, 169, 612 -628.

AMA Style

Tatheer Zahra, Manicka Dhanasekar. Characterisation and strategies for mitigation of the contact surface unevenness in dry-stack masonry. Construction and Building Materials. 2018; 169 ():612-628.

Chicago/Turabian Style

Tatheer Zahra; Manicka Dhanasekar. 2018. "Characterisation and strategies for mitigation of the contact surface unevenness in dry-stack masonry." Construction and Building Materials 169, no. : 612-628.

Journal article
Published: 01 August 2017 in Construction and Building Materials
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Application of auxetic materials in automobile and biomedical engineering is widely reported and their usage in civil engineering is emerging. This paper reports the manufacturing and characterising of cementitious polymer mortar – auxetic foam composites suitable for wall rendering. \ud \ud The deformation behaviour of the composites with the high negative Poisson’s ratio (NPR) auxetic foam embedded in polymer cement mortar matrix has been experimentally evaluated and compared to the commonly used mortar composites containing fiberglass mesh layers (that exhibits positive Poisson’s ratio). \ud \ud It is shown that the auxetic embedded polymer cement composite outperformed other composites through elimination of delamination and minimisation of brittleness. The auxetic foams used in this research were manufactured from the inexpensive open cell polyurethane foam through a thermo-mechanical process and characterised through lab tests; the maximum Poisson’s ratio determined was −1.5. \ud \ud Sixty composite specimens tested under axial compression exhibited a maximum NPR of −0.11. The results were validated numerically. The numerical model was then used to examine the effectiveness of the relative thickness of the auxetic foam layers and the polymer cement matrix for maximising the NPR of the composites. \ud \ud The results show that through auxetic material embedment, delamination and brittleness suffered by the cementitious composites could be eliminated

ACS Style

Tatheer Zahra; Manicka Dhanasekar. Characterisation of cementitious polymer mortar – Auxetic foam composites. Construction and Building Materials 2017, 147, 143 -159.

AMA Style

Tatheer Zahra, Manicka Dhanasekar. Characterisation of cementitious polymer mortar – Auxetic foam composites. Construction and Building Materials. 2017; 147 ():143-159.

Chicago/Turabian Style

Tatheer Zahra; Manicka Dhanasekar. 2017. "Characterisation of cementitious polymer mortar – Auxetic foam composites." Construction and Building Materials 147, no. : 143-159.

Book chapter
Published: 03 November 2016 in Brick and Block Masonry
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ACS Style

M. Dhanasekar; D.P. Thambiratnam; T.H.T. Chan; S. Noor-E-Khuda; T. Zahra; A Gheni; Z Aljaberi; M ElGawady; J Myers; Claudio Modena; F Da Porto; M Valluzzi. Modelling of masonry walls rendered with auxetic foam layers against vehicular impacts. Brick and Block Masonry 2016, 977 -984.

AMA Style

M. Dhanasekar, D.P. Thambiratnam, T.H.T. Chan, S. Noor-E-Khuda, T. Zahra, A Gheni, Z Aljaberi, M ElGawady, J Myers, Claudio Modena, F Da Porto, M Valluzzi. Modelling of masonry walls rendered with auxetic foam layers against vehicular impacts. Brick and Block Masonry. 2016; ():977-984.

Chicago/Turabian Style

M. Dhanasekar; D.P. Thambiratnam; T.H.T. Chan; S. Noor-E-Khuda; T. Zahra; A Gheni; Z Aljaberi; M ElGawady; J Myers; Claudio Modena; F Da Porto; M Valluzzi. 2016. "Modelling of masonry walls rendered with auxetic foam layers against vehicular impacts." Brick and Block Masonry , no. : 977-984.

Book chapter
Published: 03 November 2016 in Brick and Block Masonry
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ACS Style

T. Zahra; Z. Yin; M. Dhanasekar; M Secco; A Addis; G Artioli; Claudio Modena; F Da Porto; M Valluzzi. Experimental investigation of dry joint surface and closure characteristics of interlocking blocks under compression. Brick and Block Masonry 2016, 2003 -2010.

AMA Style

T. Zahra, Z. Yin, M. Dhanasekar, M Secco, A Addis, G Artioli, Claudio Modena, F Da Porto, M Valluzzi. Experimental investigation of dry joint surface and closure characteristics of interlocking blocks under compression. Brick and Block Masonry. 2016; ():2003-2010.

Chicago/Turabian Style

T. Zahra; Z. Yin; M. Dhanasekar; M Secco; A Addis; G Artioli; Claudio Modena; F Da Porto; M Valluzzi. 2016. "Experimental investigation of dry joint surface and closure characteristics of interlocking blocks under compression." Brick and Block Masonry , no. : 2003-2010.

Journal article
Published: 01 July 2016 in Applied Mechanics and Materials
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Building structures use brittle materials extensively. Under impact or blast loads these structures perform poorly due to tensile strains caused by Poisson’s effect normal to the direction of such loadings. Auxetic materials exhibit negative Poisson’s ratio – a property which can be exploited to eliminate those tensile strains. In this study, Auxetic layers embedded masonry is modelled using a representative volume element (RVE) with periodic boundary conditions and an explicit finite element (EFE) modelling method for a boundary value problem of a masonry wall with an Auxetic foam rendered face is subject to out-of-plane load. The RVE is limited to in-plane loads only and hence subjected to in-plane shear and compression and the EFE was used to assess the performance under out-of-plane loading. The results show significant post-yield strain hardening under axial compression and in-plane shear and high increase in capacity for walls under out of plane flexure.

ACS Style

Manicka Dhanasekar; Tatheer Zahra; Ali Jelvehpour; Sarkar Noor-E-Khuda; David P. Thambiratnam. Modelling of Auxetic Foam Embedded Brittle Materials and Structures. Applied Mechanics and Materials 2016, 846, 151 -156.

AMA Style

Manicka Dhanasekar, Tatheer Zahra, Ali Jelvehpour, Sarkar Noor-E-Khuda, David P. Thambiratnam. Modelling of Auxetic Foam Embedded Brittle Materials and Structures. Applied Mechanics and Materials. 2016; 846 ():151-156.

Chicago/Turabian Style

Manicka Dhanasekar; Tatheer Zahra; Ali Jelvehpour; Sarkar Noor-E-Khuda; David P. Thambiratnam. 2016. "Modelling of Auxetic Foam Embedded Brittle Materials and Structures." Applied Mechanics and Materials 846, no. : 151-156.

Research article
Published: 29 June 2016 in International Journal of Damage Mechanics
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A generalised model based on damage mechanics for predicting the response of masonry subjected to compression is presented. The model accounts for the behaviour of the constituents of the masonry, viz., the units, the mortar and the unit–mortar interfaces; in this paper, the unit–mortar interfaces and the mortar layers have been treated as a homogenised continuum. The principles of damage mechanics coupled with limiting damage surfaces have been used to simulate the behaviour of the masonry constituents. The novelty is the use of a non-linear, progressively stiffening stress–strain curve to simulate the viscoelastic behaviour of the homogenised mortar–interface (for conventional masonry) or dry surface–interface (for dry-stack masonry) layers until a threshold strain is reached. Beyond the threshold strain, their behaviour is assumed to have changed to progressive softening common for concrete like materials. The damage model for compression and tension due to progressive stiffening and softening criteria respectively have been formulated for the masonry constituents. The parameters which characterise the tensile and compressive behaviours, the volumetric change and the damage behaviour of the masonry constituents have been calibrated using some available experimental data in the literature. The model is shown to predict the average compressive strength and stress–strain behaviour of the masonry prisms appropriately. The model is capable of capturing the behaviour including appropriate stiffness degradation and post peak softening that are comparable to the experimental predictions reported in the literature for various types of masonry.

ACS Style

Tatheer Zahra; Manicka Dhanasekar. A generalised damage model for masonry under compression. International Journal of Damage Mechanics 2016, 25, 629 -660.

AMA Style

Tatheer Zahra, Manicka Dhanasekar. A generalised damage model for masonry under compression. International Journal of Damage Mechanics. 2016; 25 (5):629-660.

Chicago/Turabian Style

Tatheer Zahra; Manicka Dhanasekar. 2016. "A generalised damage model for masonry under compression." International Journal of Damage Mechanics 25, no. 5: 629-660.

Journal article
Published: 01 April 2016 in Construction and Building Materials
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Masonry under compression is affected by the properties of its constituents and their interfaces. In spite of extensive investigations of the behaviour of masonry under compression, the information in the literature cannot be regarded as comprehensive due to ongoing inventions of new generation products – for example, polymer modified thin layer mortared masonry and drystack masonry. As comprehensive experimental studies are very expensive, an analytical model inspired by damage mechanics is developed and applied to the prediction of the compressive behaviour of masonry in this paper. The model incorporates a parabolic progressively softening stress–strain curve for the units and a progressively stiffening stress–strain curve until a threshold strain for the combined mortar and the unit-mortar interfaces is reached. The model simulates the mutual constraints imposed by each of these constituents through their respective tensile and compressive behaviour and volumetric changes. The advantage of the model is that it requires only the properties of the constituents and considers masonry as a continuum and computes the average properties of the composite masonry prisms/wallettes; it does not require discretisation of prism or wallette similar to the finite element methods. The capability of the model in capturing the phenomenological behaviour of masonry with appropriate elastic response, stiffness degradation and post peak softening is presented through numerical examples. The fitting of the experimental data to the model parameters is demonstrated through calibration of some selected test data on units and mortar from the literature; the calibrated model is shown to predict the responses of the experimentally determined masonry built using the corresponding units and mortar quite well. Through a series of sensitivity studies, the model is also shown to predict the masonry strength appropriately for changes to the properties of the units and mortar, the mortar joint thickness and the ratio of the height of unit to mortar joint thickness. The unit strength is shown to affect the masonry strength significantly. Although the mortar strength has only a marginal effect, reduction in mortar joint thickness is shown to have a profound effect on the masonry strength. The results obtained from the model are compared with the various provisions in the Australian Masonry Structures Standard AS3700 (2011) and Eurocode 6.

ACS Style

Tatheer Zahra; Manicka Dhanasekar. Prediction of masonry compressive behaviour using a damage mechanics inspired modelling method. Construction and Building Materials 2016, 109, 128 -138.

AMA Style

Tatheer Zahra, Manicka Dhanasekar. Prediction of masonry compressive behaviour using a damage mechanics inspired modelling method. Construction and Building Materials. 2016; 109 ():128-138.

Chicago/Turabian Style

Tatheer Zahra; Manicka Dhanasekar. 2016. "Prediction of masonry compressive behaviour using a damage mechanics inspired modelling method." Construction and Building Materials 109, no. : 128-138.

Journal article
Published: 01 January 2014 in Case Studies in Construction Materials
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ACS Style

Tatheer Zahra; Yasmeen Zehra; Shuaib Ahmad. Condition assessment and strengthening of residential units. Case Studies in Construction Materials 2014, 1, 144 -153.

AMA Style

Tatheer Zahra, Yasmeen Zehra, Shuaib Ahmad. Condition assessment and strengthening of residential units. Case Studies in Construction Materials. 2014; 1 ():144-153.

Chicago/Turabian Style

Tatheer Zahra; Yasmeen Zehra; Shuaib Ahmad. 2014. "Condition assessment and strengthening of residential units." Case Studies in Construction Materials 1, no. : 144-153.