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Assessment of the ACI-DAfStb Database of Shear Tests on Slender Reinforced Concrete Beams without Stirrups for Investigations on the Shear Capacity Scatter
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.ORCID iD: 0000-0002-1526-9331
Politecnico di Torino.
2014 (English)In: Athens Journal of Technology & Engineering, ISSN 2241-8237, Vol. 1, no 3, 181-197 p.Article in journal (Refereed) Published
Abstract [en]

The shear transfer mechanism of RC slender members without stirrups still presents very high uncertainties and the question has generated many controversies and debates since the beginning of the last century. Regrettably, until now the real causes of this problem are not yet clear to the scientific community and the issue is still important to investigate, especially nowadays that the minimizing of natural resources is of uppermost global interest.

Due to the increased laboratory costs, actual studies are more and more often devoted to numerical simulations based on previous experiments. Unfortunately, it is difficult to find test results suitable for investigations on the shear capacity scatter in the available specialized literature.

Therefore, the objective of this paper is to provide different adequate sets of reported test results containing tests performed on almost identical beams. The ACI-DAfStb database of shear tests on slender reinforced concrete beams without stirrups is considered and analyzed through the use of both multivariate statistical methods and clustering data mining techniques. The database was firstly visually explored by scatterplots and investigated through both univariate and correlation statistical procedures, and then processed by clustering using the k-means algorithm. Similar sets of data were collected in groups of comparable experiments. Clusters containing less than six data sets48were removed. The criteria to establish the rate of similarity between each set of data were chosen according to the JCSS Probabilistic Model Code.

The study has led to the formation of 13 groups of comparable experiments each group containing a number of tests between 6 and 43, performed generally by different field workers. These groups of reported test results will be of great importance both for the continuation of the authors' research and for other researchers who investigate the causes of the shear failure scatter or develop improved shear design methods.

Place, publisher, year, edition, pages
2014. Vol. 1, no 3, 181-197 p.
National Category
Infrastructure Engineering
Identifiers
URN: urn:nbn:se:kth:diva-164299OAI: oai:DiVA.org:kth-164299DiVA: diva2:805393
Note

QC 20150415

Available from: 2015-04-15 Created: 2015-04-15 Last updated: 2015-04-16Bibliographically approved
In thesis
1. Safety Format for Non-linear Analysis of RC Structures Subjected to Multiple Failure Modes
Open this publication in new window or tab >>Safety Format for Non-linear Analysis of RC Structures Subjected to Multiple Failure Modes
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis treats the safety format for non-linear analysis of reinforced concrete (RC) structures subjected to multiple failure modes. The purpose is to identify questions which are poorly understood and ambiguous about the behaviour of structures that may fail due to a number of possible failure modes (e.g., bending, shear, buckling, crack propagation, fatigue) which might be used as a focus for the development of a more comprehensive approach to the evaluation of the structural safety level.

Nowadays non-linear analysis in concrete structures cannot be considered only as a research tool to improve the understanding of structural behaviour, but it is also a useful mean to design more and more enhanced structures and to estimate the actual safety level in existing structures. As a consequence, semi-probabilistic safety formats for the non-linear analysis of RC structures are of great practical interest for structural engineers.

Safety formats for non-linear analysis have mainly been tested on beams and columns subjected to normal forces and bending moments. Only recently there has been a noticeable effort in understanding whether available safety formats lead to the intended reliability when they are applied to structures that also may fail due to shear forces. However, the road ahead is still long and challenging.

The definition of a suitable safety format involves the clarification of (i) which values of geometric and material properties should be used in the non-linear analysis, considering that they all influence both the resistance and the ultimate behaviour of the whole system, (ii) when the incremental process of non-linear analysis should stop, and (iii) how to derive from the failure load the ultimate load that can be carried by the structure with the safety margins that are required by the semi-probabilistic approach. This thesis considers in some sense all three of these aspects.

The following major conclusions are based on the studies described in the appended papers: (1) the scatter of the shear capacity of RC slender members seems to be mainly due to the randomness of both tensile strength of concrete and shrinkage; (2) the structural behaviour at ultimate load of RC structures designed according to Eurocodes 2 is not unambiguous and may significantly vary depending on the structural system, load configuration, and capacity design; (3) the resistance of RC structures subjected to flexural and shear failure modes seems to be mainly influenced by the combination of mechanical properties of both longitudinal reinforcement and stirrups, and tensile strength of concrete; and (4) the resistance of RC structures subjected to multiple failure modes may have a general multimodal probability density function, in which each mode represents a specific failure mechanism.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xii, 45 p.
Series
TRITA-BKN. Bulletin, ISSN 1103-4270 ; 127
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-164304 (URN)
Public defence
2015-05-06, Aula Albenga, Corso Duca degli Abruzzi 24, Torino, Italy, 10:00 (English)
Opponent
Supervisors
Note

QC 20150416

Available from: 2015-04-16 Created: 2015-04-15 Last updated: 2015-04-16Bibliographically approved

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