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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 898 Abstracts search results
October 1, 2020
Barros, J.A.O.; Foster, S.J.
For the development of reliable physical-mechanical models for predicting the behaviour
of fibre reinforced concrete structures at service and strength limit conditions, constitutive
models simulating comprehensibly the governing phenomena must be used. In this context,
simulating the post-cracking mechanisms of the fibres, and their symbiotic relationship with
the cementitious matrix that surrounds them, is required for the development of realistic
modelling approaches that accurately represent empirical observations. Several experimental
test setups and inverse analysis procedures have been proposed to derive the fundamental
stress-crack width ( –w) law, but a consensus still does not exists on the best strategy for its
determination. In structures governed by shear, fibre reinforcement increases the stiffness and
shear stress transfer across a crack, but a methodology to capture the contribution of fibres in
this regards is challenging. To overcome this, a clear strategy is needed in deriving
relationships that simulate fibre reinforcement mechanisms in the mobilized fracture modes
and, also, develop design approaches capable of capturing the relevant contributions of the
fibres. This study firstly reviews current inverse analysis models used to describe the tensile
(Model I fracture) relationship for FRC and, secondly, discusses a newly proposed model,
referred to as the integrated shear model (ISM). The ISM is developed from mesoscale
observations from gamma- and X-ray imaging on FRC elements under Modes I and II
fracture conditions. The resulting model is compared to test data reported in the literature and
a good correlation is observed.
Vrijdaghs, R.; Di Prisco, M.; Vandewalle, L.
The creep behavior of FRC elements remains an important obstacle to use FRC in structural
applications. Owing to the residual post-cracking strength properties of FRC, creep
deformations play an important role in the cracked sections and influence durability and SLS
requirements of structural elements. Therefore, it is of high importance to take creep
deformations into account in the design phase.
In this paper, the results of an experimental campaign involving both bending tests and
uniaxial tensile creep tests on polymeric FRC are presented. In the bending tests, a notched
FRC beam is subjected to loading-unloading cycles while the deformations over the cracked
section were recorded. The uniaxial tensile creep tests were performed on precracked FRC
samples to quantify time-dependent crack growth.
The bending behavior of FRC can be accurately predicted by the uniaxial constitutive model
of Model Code 2010 in the loading phase assuming a plane section approach. For the unloading
phases, a bilinear deformation distribution is assumed and a scalar damage evolution function
is fitted by an inverse analysis algorithm. The results of the sectional analysis compared
favorably with the experimentally observed data.
Finally, a sectional analysis approach is developed and presented in which bending creep
deformations are calculated using the uniaxial creep compliances. The initial stress and
deformation distribution in the cracked section is predicted by the inverse analysis. The results
show that the bending creep deformations of FRC can be quite large, and creep coefficients as
high at 7 are observed within 120 days. However, it should be noted that the creep algorithm
does not (yet) take into account additional cracking in time, and as such, the predicted creep
deformations are a lower limit of what can be expected in reality. More research is needed to
upgrade the algorithm to allow predictions including the time-dependent cracking behavior.
Lucchini, S.S.; Facconi, L.; Minelli, F.; Plizzari, G.A.
The use of mortar coating reinforced only with randomly diffused steel fibers represents an
effective technique for seismic retrofitting of masonry buildings. The present work aims at
proving the effectiveness of that technique by testing a full-scale two-story hollow clay block
masonry building subjected to a quasi-static cyclic lateral loading. The experimental program
includes two tests involving the same building. The first test performed on the building
without coating is carried out to pre-damage masonry in order to simulate the effects of a
seismic action significant for ultimate conditions. The second test is performed to assess the
behavior of the pre-damaged building after retrofitting. The paper presents the main properties
and details of both the test building and the proposed retrofitting technique. As the test on the
retrofitted specimen is still ongoing, only the main results concerning the unstrengthened
building are reported and discussed.
To predict the response of the two experimental tests, 3D non-linear finite element
simulations have been carried out and presented in the last section of the paper. The latter
includes the comparison between the numerical prediction and the available experimental
Look, K.; Mark, P.
An open design tool is developed that uses spreadsheet analyses, optimisation methods and
iterative analytical routines. Its idea is to offer a universal, intuitive instrument to economically
design and optimise steel fibre reinforced concrete members with or without rebar. The tool
comprises non-linear evaluations of sectional forces with the yield line theory, a cross sectional
design in ultimate and serviceability limit states as well as backward oriented optimisations of
reinforcements, cross sectional properties or fibre classes. It should be free of specific code
regulations and thus just basis on the assumption of plane strains, an ideal bond and requires
the definitions of uniaxial stress-strain laws, strain boundaries and fundamental design
formulas. Boundary conditions, material parameters and sectional properties as well as results
like strain or stress distributions, performance ratios and potentials of improvements are given
in visualisations and commented figures. The non-linear equations of equilibrium are iteratively
solved with reduced gradient methods. Doing so, recursive initial parameter settings of the
strain plane are – amongst other regularisations – incorporated to achieve robust solutions.
Zanotti, C.; Randl, N.; Gar, P.S.; Far, B.K.; Steiner, M.
Fiber Reinforced Concrete (FRC) is being increasingly applied in structural repair and
retrofit of reinforced concrete structures. Not only fiber reinforcement improves the durability
of reinforced concrete structures, but it also enhances compatibility of the repair material to
the existing structure, further enhancing structural effectiveness and service life of the
intervention. Furthermore, studies have shown that fiber reinforcement can significantly
improve substrate-repair bond in both tension and shear. However, this benefit is not fully
utilized in repair/retrofit design due to test uncertainties and lack of comprehensive data on
correlations with other fundamental factors. In this study, the question of the appropriateness,
reliability and sensitivity of current bond tests in case of FRC repairs is addressed. Several
tension and shear bond tests on plain and fiber reinforced cement-based repairs are performed
in parallel by two research teams at UBC (Canada) and CUAS (Austria), following a rigorous
testing procedure to allow consistency among results from the two laboratories. The influence
of repair strength and casting direction is also investigated. The effect of fiber reinforcement
on bond is assessed while correlation, comparability, and sensitivity of different test set-ups
and stress conditions are discussed.
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