2,414 research outputs found
On a three-dimensional lattice approach for modelling corrosion induced cracking and its influence on bond between reinforcement and concrete
The present work involves the discrete modelling of corrosion induced
cracking and its influence on the bond between reinforcement and concrete. A
lattice approach is used to describe the mechanical interaction of a corroding
reinforcement bar, the surrounding concrete and the interface between steel
reinforcement and concrete. The cross-section of the ribbed reinforcement bar
is taken to be circular, assuming that the interaction of the ribs of the
deformed reinforcement bar and the surrounding concrete is included in a
cap-plasticity interface model. The expansion of the corrosion product is
represented by an eigenstrain in the lattice elements forming the interface.
The lattice modelling approach is applied to the analysis of corrosion induced
cracking and its influence of the bond strength. The model capabilities are
assessed by comparing results of analyses with those from unconfined pull-out
tests reported in the literature. Future work will investigate the influence of
the stiffness of interface elements and the effect of lateral confinement on
corrosion induced cracking.Comment: Preprint of conference paper for Fracture Mechanics of Concrete and
Concrete Structures, South Korea, 201
Cap reform: implications for Ireland
working paperIncreasingly farmers can be viewed as multifunctional providers of a range of
commodity and non-commodity goods that are valued by society. Changes to the
Common Agricultural Policy (CAP) such as the shift towards decoupled payments not
only have significant effects on agriculture but also rural areas and society more
generally. Given that the CAP is likely to be the most significant driving force for
change in the Irish countryside, it will be important to assess the impact of policy
changes. Using a dynamic, multi-product, partial equilibrium model, this paper firstly
examines the potential impact of recent policy changes accruing from the Mid-Term
Review of the Common Agricultural Policy (CAP). In addition, this paper highlights
additional potential reforms of the CAP and discusses their implications for the Irish
agricultural sector.European Commission 6th Framewor
Wiener Index and Remoteness in Triangulations and Quadrangulations
Let be a a connected graph. The Wiener index of a connected graph is the
sum of the distances between all unordered pairs of vertices. We provide
asymptotic formulae for the maximum Wiener index of simple triangulations and
quadrangulations with given connectivity, as the order increases, and make
conjectures for the extremal triangulations and quadrangulations based on
computational evidence. If denotes the arithmetic mean
of the distances from to all other vertices of , then the remoteness of
is defined as the largest value of over all vertices
of . We give sharp upper bounds on the remoteness of simple
triangulations and quadrangulations of given order and connectivity
Functional and Structural MRI Studies on Impulsiveness: Attention-Deficit/Hyperactive Disorder and Borderline Personality Disorders
Description to be added.Cannot be left empt
Application of LRFD Geotechnical Principles for Pile Supported Bridges in Oregon: Phase 1
Bridge foundations must be designed based on acceptable risks of failure. To secure rapid implementation of Load Resistance Factor Design (LRFD) principles for foundation design, the American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway Administration (FHWA) are requiring their use through AASHTO code. The Bridge Section of the Oregon Department of Transportation (ODOT) has responsibility for satisfactory design of all the bridge structures across the state’s highway system. The widespread geotechnical adoption of the LRFD code throughout state DOTs has been difficult in the case of deep foundations due to regional differences and in some cases a lack of any close match to DOT foundation practices. This lack of matching stems from the source research conducted on which the code is based, documented as NCHRP 507. For ODOT, the evaluation of nominal axial static capacity for each driven pile in the field is conducted by dynamic methods and AASHTO offers resistance factors for these techniques. ODOT typically uses the wave equation software (WEAP) applied at the end of initial driving, EOID, and occasionally at the beginning of pile restrike (BOR) to capture increases in capacity from set-up. This study reports that, based on past and new surveys, ODOT practice is reasonably typical for DOT practice in sands, silts, and clays. The AASHTO resistance factor, φ, for WEAP is at EOID and is too low for the efficient design of piles to match the likely probabilities of pile failure. The survey of Northwest state DOTs revealed that 80% of the DOTs believe that a φ of 0.4 is conservative and 37.5 % do not use the AASHTO-sanctioned φ of 0.4. Matching LRFD to allowable stress design (ASD) by direct calibration for a single pile, without any reported capacity bias, sets φ as 0.55 to match the ASD factor of safety of 2.5. An ODOT case history of a recently completed pilesupported bridge designed and constructed to FHWA and AASHTO ASD standards in use at that time, shows the number of piles at the bent studied would be doubled under new AASHTO requirements. This suggests the standard will add considerable pile foundation costs to all new bridges. This cost increase is a strong incentive to complete statistical recalibration of GRLWEAP dynamic capacity resistance value in a Phase 2 of this study
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