CORDIS fornisce collegamenti ai risultati finali pubblici e alle pubblicazioni dei progetti ORIZZONTE.
I link ai risultati e alle pubblicazioni dei progetti del 7° PQ, così come i link ad alcuni tipi di risultati specifici come dataset e software, sono recuperati dinamicamente da .OpenAIRE .
Risultati sfruttabili
Recommendations for advanced concrete compositions for material testing
The Round Robin test programme highlights the changes in thermo-mechanical properties of a young maturing concrete tested in different laboratories. Strong efforts were devoted setting up suitable testing methods for non-hardened concrete samples. The changes in compressive and tensile strength and in elastic modulus are well put in evidence for two different thermal histories: constant temperature of 20°C and realistic temperature reproducing a true maturing concrete condition on site. Comprehensive efforts have been devoted to the two most fundamental parameters for cracking risk estimations: autogenous deformation and thermal expansion at early age. The Round Robin tests have put in evidence the utmost need to separate in the laboratory the studies on thermal strain from those on non-thermal strain and this has opened a new field of investigation where much experimental work is still required. The results of tests performed by Temperature Stress Testing Machines represent the crucial item of the Round Robin testing programme. It is informed on the state of the art on equipments, testing methods and testing recommendations. Temperature Stress Testing Machine tests have been performed under constant and realistic temperatures. Highly reliable results can be achieved provided that a quality control on the concrete mixing procedure is assured.
Expert System/Material Data Base
The materials database
The IPACS materials database is a repository for data and experimental test results gathered in the project. It contains extensive information of more than 100 concrete mixes. It is structured to accept concrete mix information to any available level of detail. Test results related to the individual concrete mixtures are stored as ASCII text files, and the database allows storage of essentially any kind of test results. Time series data can be stored and presented by the software as x-y plots. The underlying database is in Microsoft Access format, with an interface written in Pearl for access via Internet.
Latest materials knowledge
The traditional maturity concept is not sufficient for describing the effect of temperature on the deformational behaviour of hardening concrete. Better understanding of the evolution of microstructure and the materials properties is needed. A number of theoretical and experimental studies have been performed in view of increasing our knowledge about the relationship between materials properties and microstructure. New experimental research techniques, some of them developed within the IPACS project, have provided us with research results for developing advanced materials models. With the help of these results and the derived material models the behaviour of young concrete now can be described with increasing accuracy and reliability.
Expert System/Neural Network
The neural network technology adopted within the E.S. to allow for the prediction of cracking risk and restraint factors for some relevant structural cases. Cracking risk results obtained from sophisticated models (thermo-viscoelastic or thermo-elastic equivalent) have been used to calibrate such nets with thousands of data. The accuracy on the resulting cracking risk is 2-5%. Currently the nets implemented in the E.S. accept dimensional geometrical and environmental variables, whereas the material ones are fixed. This technology has substantial potentials because it spreads the use of state of the art are needed to exploit acceptance criteria based on cracking risk, which currently requires substantial engineers knowledge and modelling experience. The same technology has been used to calculate the restraint factor for five typical cases of restraint, which are available in the K.B. section of the E.S. Also in this case this technology allowed incorporating results of different nature (ACI regulations, numerical and experimental evaluations). The nets allow the evaluation of the restraint factors, having known the geometrical variables of the following cases:
- Structure facing grounds.
- Slab to slab.
- Wall on slab.
- Roof on wall.
- Wall on wall.
Expert System/Knowledge Based Module
The Knowledge Based Module consists of computer programs based on deterministic models and well-established numerical procedures. The different modules cover a chain from knowledge on basic data to direct application for simplified situations and crack risk estimations. The main situation when the knowledge-based module will be used is in the pre-design phase where a fast and reliable enough method validates the decisions to be taken in advance. Generally speaking, the knowledge based modules for stress calculation may also treat any complicated situation if the following two conditions are fulfilled: Temperature is taken from 3D calculations (or measurements) and the restraint factors are taken from some sophisticated analysis.
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