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Jason Ingham - One of the best experts on this subject based on the ideXlab platform.

  • pullout strength of nsm cfrp strips bonded to vintage clay Brick Masonry
    Engineering Structures, 2014
    Co-Authors: Dmytro Dizhur, M C Griffith, Jason Ingham
    Abstract:

    Abstract The frequently observed inadequate seismic performance of unreinforced Masonry (URM) buildings necessitates the development of cost effective minimally-invasive seismic improvement techniques for this type of construction. One promising solution is use of the near surface mounted (NSM) technique to incorporate fibre reinforced polymers (FRP) strips as longitudinal reinforcement. In particular, the NSM technique provides several advantages over externally bonded (EB) FRP as a seismic improvement technique including significantly higher axial strain at debonding, minimal negative impact upon the aesthetics of the structure, reduced installation time, and superior protection from fire and the environment, thus providing a cost effective and minimally-invasive option for seismically strengthening URM buildings. An experimental program consisting of 39 pull tests was conducted using NSM carbon (C)FRP strips bonded to vintage solid clay Brick Masonry, to provide data with which to validate the accuracy of existing predictive FRP-to-Masonry bond models. Based on experimental findings, a variation of an existing analytical FRP-to-Masonry bond model is proposed and the effects of geometric variation of the NSM groove and the reinforcing CFRP strip are discussed.

  • Diagonal tension strength of vintage unreinforced clay Brick Masonry wall panels
    Construction and Building Materials, 2013
    Co-Authors: Dmytro Dizhur, Jason Ingham
    Abstract:

    Abstract An experimental program was implemented where wall panels were obtained from two existing vintage unreinforced clay Brick Masonry (URM) buildings and subjected to a diagonal compression loading condition in order to induce a diagonal tension failure mode. The principal aims of the experimental program were to establish the diagonal tension strength of the vintage clay Brick URM walls present in the two buildings and to establish a benchmark mortar mix suitable for use when manufacturing replica clay Brick test assemblages that adequately represent the strength characteristics present in vintage URM buildings. It was concluded that the use of recycled clay Bricks acquired from vintage URM buildings and a mortar mix of 1:2:9 (cement:lime:sand) appropriately replicates the material strength characteristics that are present in existing vintage clay Brick URM buildings located in New Zealand.

  • cyclic out of plane behavior of slender clay Brick Masonry walls seismically strengthened using posttensioning
    Journal of Structural Engineering-asce, 2012
    Co-Authors: Najif Ismail, Jason Ingham
    Abstract:

    AbstractEquations for the design of a posttensioned seismic retrofit of unreinforced clay Brick Masonry walls are discussed, and results from an associated experimental program are reported. A total of eight full-scale multiwythe vintage solid clay Brick Masonry walls were subjected to uniformly distributed one-directional and reverse cyclic out-of-plane loading, of which two walls were tested as built and six walls were seismically retrofitted using unbonded posttensioning. Test wall configurations and constituent Masonry materials were selected to replicate typical characteristics of historic clay Brick Masonry walls. The test walls were seismically retrofitted by applying varying magnitudes of posttensioning using a single tendon inserted into a cavity located at the center of each test wall. Several aspects pertaining to the seismic behavior of posttensioned Masonry walls were investigated, including damage patterns, force-displacement behavior, tendon stress variation, wall secant stiffness, hysteret...

  • debonding resistance of frp to clay Brick Masonry joints
    Engineering Structures, 2012
    Co-Authors: J Kashyap, C Willis, Jason Ingham, M C Griffith, Mark J Masia
    Abstract:

    Abstract Debonding at the FRP-to-Masonry interface has been identified as the preferred failure mechanism in fibre-reinforced polymer (FRP) retrofitted Masonry as it allows for some redistribution of forces. The results of 14 FRP-to-Masonry bond tests are presented, where the FRP was near surface mounted (NSM) to stack-bonded clay Brick Masonry. These tests were conducted to investigate the effect that variables such as cyclic loading and FRP strip dimensions have on the debonding resistance of a NSM FRP-to-Masonry joint. These results were then incorporated into a large database of FRP retrofitted Masonry pull test results by various researchers over the past 10 years. The database includes results for both externally bonded (EB) and NSM retrofitting techniques. From this database, local bond–slip parameters such as the maximum interface shear stress, τmax, and the maximum slip, δmax, were investigated to determine correlations between these values and Masonry material properties. Further, 15 existing concrete and Masonry bond strength (maximum load at the FRP-to-substrate interface) models in the literature were assessed for their use with Masonry by comparing these models against the results in the pull test database. Based on the comparative statistics of the test-to-predicted bond strength it is concluded that a new FRP-to-Masonry bond model is required which gives more accurate predictions. Results include a discussion on the global load–slip response and FRP-to-Masonry interface behaviour.

M C Griffith - One of the best experts on this subject based on the ideXlab platform.

  • durability of near surface mounted frp to clay Brick Masonry retrofits under environmental exposure
    Journal of Composites for Construction, 2020
    Co-Authors: J Vaculik, P Visintin, Wade Lucas, M C Griffith
    Abstract:

    AbstractThis study presents an experimental investigation of the effect of environmental exposure on the fiber-reinforced polymer (FRP) to clay Brick Masonry bond when the reinforcement is near-sur...

  • pullout strength of nsm cfrp strips bonded to vintage clay Brick Masonry
    Engineering Structures, 2014
    Co-Authors: Dmytro Dizhur, M C Griffith, Jason Ingham
    Abstract:

    Abstract The frequently observed inadequate seismic performance of unreinforced Masonry (URM) buildings necessitates the development of cost effective minimally-invasive seismic improvement techniques for this type of construction. One promising solution is use of the near surface mounted (NSM) technique to incorporate fibre reinforced polymers (FRP) strips as longitudinal reinforcement. In particular, the NSM technique provides several advantages over externally bonded (EB) FRP as a seismic improvement technique including significantly higher axial strain at debonding, minimal negative impact upon the aesthetics of the structure, reduced installation time, and superior protection from fire and the environment, thus providing a cost effective and minimally-invasive option for seismically strengthening URM buildings. An experimental program consisting of 39 pull tests was conducted using NSM carbon (C)FRP strips bonded to vintage solid clay Brick Masonry, to provide data with which to validate the accuracy of existing predictive FRP-to-Masonry bond models. Based on experimental findings, a variation of an existing analytical FRP-to-Masonry bond model is proposed and the effects of geometric variation of the NSM groove and the reinforcing CFRP strip are discussed.

  • debonding resistance of frp to clay Brick Masonry joints
    Engineering Structures, 2012
    Co-Authors: J Kashyap, C Willis, Jason Ingham, M C Griffith, Mark J Masia
    Abstract:

    Abstract Debonding at the FRP-to-Masonry interface has been identified as the preferred failure mechanism in fibre-reinforced polymer (FRP) retrofitted Masonry as it allows for some redistribution of forces. The results of 14 FRP-to-Masonry bond tests are presented, where the FRP was near surface mounted (NSM) to stack-bonded clay Brick Masonry. These tests were conducted to investigate the effect that variables such as cyclic loading and FRP strip dimensions have on the debonding resistance of a NSM FRP-to-Masonry joint. These results were then incorporated into a large database of FRP retrofitted Masonry pull test results by various researchers over the past 10 years. The database includes results for both externally bonded (EB) and NSM retrofitting techniques. From this database, local bond–slip parameters such as the maximum interface shear stress, τmax, and the maximum slip, δmax, were investigated to determine correlations between these values and Masonry material properties. Further, 15 existing concrete and Masonry bond strength (maximum load at the FRP-to-substrate interface) models in the literature were assessed for their use with Masonry by comparing these models against the results in the pull test database. Based on the comparative statistics of the test-to-predicted bond strength it is concluded that a new FRP-to-Masonry bond model is required which gives more accurate predictions. Results include a discussion on the global load–slip response and FRP-to-Masonry interface behaviour.

  • out of plane strength of Brick Masonry retrofitted with horizontal nsm cfrp strips
    Engineering Structures, 2010
    Co-Authors: C Willis, R Seracino, M C Griffith
    Abstract:

    Abstract The magnitude of damage possible in unreinforced Brick Masonry construction subjected to high levels of out-of-plane loading is well understood. Due to the large global building stock of Masonry structures, it is essential that efficient retrofitting techniques be developed. The use of fibre-reinforced polymer (FRP) strips has been shown to improve the load-carrying and displacement capacities of Masonry sections subjected to out-of-plane loading. This paper presents the results of an experimental and theoretical investigation into the behaviour of modern clay Brick Masonry retrofitted with horizontally oriented FRP strips subjected to horizontal bending. Experimental tests were conducted on four Masonry wallettes retrofitted with horizontal near-surface mounted (NSM) carbon FRP strips, subjected to horizontal bending. The specimens were tested in a vertical orientation with variation in vertical compressive loading. The application of compressive load improved the FRP confinement efficiency, and thus increased the maximum strength of the specimens. The primary failure modes were displacement induced (DI) debonding and FRP buckling. Mathematical models were developed to predict the moment at cracking and moment capacity for the specimens. The models explicitly account for the flexural strengths of the mortar and Brick units, the torsional resistance of the bed joints, the NSM FRP, as well as the contributions to bed joint shear strength from the vertical compressive stress and friction. The proposed mathematical models were validated against the results of the experimental tests.

  • bond behaviour of frp to clay Brick Masonry joints
    Engineering Structures, 2009
    Co-Authors: C Willis, Q Yang, R Seracino, M C Griffith
    Abstract:

    Abstract The out-of-plane bending and in-plane shear response of unreinforced modern clay Brick Masonry walls retrofitted with fibre-reinforced polymer (FRP) strips is often governed by debonding failure mechanisms. Hence, it is necessary to quantify the fundamental interface bond–slip model, which describes the debonding behaviour of the FRP-to-Masonry interface. This paper presents the results of a series of 29 pull tests investigating the use of externally bonded (EB) and near surface mounted (NSM) retrofitting techniques. Test variables included: surface preparation; geometric properties; location of FRP (relative to perpend joints and cores); bonding agent of bed joints (mortar and quick drying paste); bonding method for glass fibre sheets (plate bonding and dry lay-up); and FRP material. A discussion of the test results and preliminary practical recommendations are also provided. A model used to predict the intermediate crack debonding resistance was verified against the test data. The model is generic in that it is applicable to both the EB and NSM retrofitting techniques. This generic model was shown to give very good ultimate strength predictions for the series of 29 pull tests conducted as part of this research.

Rudolf Seracino - One of the best experts on this subject based on the ideXlab platform.

Mervyn J. Kowalsky - One of the best experts on this subject based on the ideXlab platform.

  • reversed in plane cyclic behavior of posttensioned clay Brick Masonry walls
    Journal of Structural Engineering-asce, 2004
    Co-Authors: Owen Rosenboom, Mervyn J. Kowalsky
    Abstract:

    A series of five large scale clay Brick Masonry structural walls are subjected to in-plane simulated seismic forces. The walls utilize posttensioning steel to provide flexural strength. The primary objective of the research is to investigate five basic configurations of posttensioning to determine which has the most desirable characteristics for seismic performance. In the study, the variables of interest were ! 1" bonded versus unbonded posttensioning steel, ! 2" confined versus unconfined Masonry, ! 3" grouted versus ungrouted Masonry, and ! 4" application of supplemental mild steel for energy dissipation. Following the results of the tests, it was shown that the best performing configuration utilized unbonded posttensioning and confinement. By utilizing unbonded posttensioning, walls have little residual deformation after loading, thus yielding structures that would require very little repair, even after large seismic events. Such behavior comes with the price of reduced energy dissipation, however. Presented in the paper are the results of the tests as well as results of a simple analysis method for prediction of wall capacity.

  • Compressive Behavior of Unconfined and Confined Clay Brick Masonry
    Journal of Structural Engineering-asce, 2004
    Co-Authors: Bryan Darnell Ewing, Mervyn J. Kowalsky
    Abstract:

    Presented in this paper are the results of an investigation of the compressive behavior of grouted clay Brick Masonry prisms. The objective is to experimentally capture the stress–strain characteristics of unconfined and confined clay Brick Masonry and compare the response with that predicted with the “modified” Kent–Park stress–strain curve. Based on the experimental results, five limit states for clay Brick Masonry in compression are proposed, as well as equivalent stress blocks for design. Thin galvanized steel plates placed in the mortar joints during construction provided prism confinement. The variables considered included volumetric ratio of confining steel (0, ∼0.015, and ∼0.03) and the presence of machined holes within the confinement plates to improve the bond between the Masonry and steel plate. It is shown that confinement plates are extremely effective in enhancing the ultimate compressive strength as well as increasing the deformation capacity of the clay Brick Masonry prisms. The use of con...

R B Petersen - One of the best experts on this subject based on the ideXlab platform.