281 research outputs found
Shear Capacity of Monolithic Concrete Joints without Transverse Reinforcement.
yesA mechanism analysis based on the upper-bound theorem of concrete plasticity for monolithic concrete joints without transverse reinforcement is presented. Concrete is modelled as a rigid–perfectly plastic material obeying modified Coulomb failure criteria. Existing stress–strain relationships of concrete in compression and tension are comprehensively modified using the crack band theory to allow for concrete type and maximum aggregate size. Simple equations for the effectiveness factor for compression, ratio of effective tensile strength to compressive strength and angle of concrete friction are then mathematically developed using the modified stress–strain relationships of concrete. In addition, 12 push-off specimens made of all-lightweight, sand–lightweight and normal-weight concrete having maximum aggregate size between 4 and 19 mm were physically tested. Test results and mechanism analysis clearly showed that the shear capacity of monolithic concrete joints increased with the increase of the maximum aggregate size and dry density of concrete. The mean and standard deviation of the ratio between experimentally measured and predicted (by the mechanism analysis shear capacities) are 1·01 and 0·16 respectively, showing a closer prediction and less variation than Vecchio and Collins' equation, regardless of concrete type and maximum aggregate size
Validation of a simplified micromodel for analysis of infilled RC frames exposed to cyclic lateral loads
An RC frame structure with masonry infill walls (‘‘framed-masonry’’) exposed
to lateral loads acts as a composite structure. Numerical simulation of framed-masonry is
difficult and generally unreliable due to many difficulties and uncertainties in its modelling.
In this paper, we reviewed the usability of an advanced non-linear FEM computer
program to accurately predict the behaviour of framed-masonry elements when exposed to
cyclic lateral loading. Numerical results are validated against the test results of framedmasonry
specimens, with and without openings. Initial simplified micromodels were calibrated
by adjustment of the input parameters within the physically justifiable borders, in
order to obtain the best correlation between the experimental and numerical results. It has
been shown that the use of simplified micromodels for the investigation of composite
masonry-infilled RC frames requires in-depth knowledge and engineering judgement in
order to be used with confidence. Modelling problems were identified and explained in
detail, which in turn offer an insight to practising engineers on how to deal with them
A model for reactive porous transport during re-wetting of hardened concrete
A mathematical model is developed that captures the transport of liquid water
in hardened concrete, as well as the chemical reactions that occur between the
imbibed water and the residual calcium silicate compounds residing in the
porous concrete matrix. The main hypothesis in this model is that the reaction
product -- calcium silicate hydrate gel -- clogs the pores within the concrete
thereby hindering water transport. Numerical simulations are employed to
determine the sensitivity of the model solution to changes in various physical
parameters, and compare to experimental results available in the literature.Comment: 30 page
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