Assessment of the ACI-DAfStb Database of Shear Tests on Slender Reinforced Concrete Beams without Stirrups for Investigations on the Shear Capacity Scatter

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 sets were 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.