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Purpose In reinforced concrete (RC) structures, an evidence of damage is the presence of cracking. In order to evaluate the effect of damage on cracking pattern and natural frequency in RC slabs, two of such structures with different dimensions and reinforcement ratios were tested, in which cracks were induced through application of static load, followed by modal tests using impact excitation. The paper aims to discuss this issue. Design/methodology/approach The gradient of the fundamental natural frequency along the decay, the crack opening rate and also a global damage index based on changes of the fundamental natural frequency were evaluated. Findings The behaviour of the aforementioned gradient was distinct for both slabs, increasing monotonically with the cracking level for the slab with lowest reinforcement ratio, and increasing until 33 per cent of the collapse load and then decreasing afterwards for the slab with the highest ratio. Changes of the gradient were consistent with changes of the crack opening rate. Both results of gradient changes and cracking pattern brought evidence that the balance between open (old) and breathing (new) cracks differed between the slabs, and may be responsible for such differences. Originality/value Damage assessment in RC structures using vibration tests is mostly concentrated on beams. In this work, an advance is made by investigating slabs. The lack of a unique pattern of changes of the gradient implies that its absolute value is not generally suitable for the association with the damage level. However, the impact tests can be effectively used to detect early damage on slabs using this proposed parameter.

A high diversity of land vertebrates is known from the Late Cretaceous deposits of the Bauru 21 Basin, Brazil, including at least five turtle taxa, all belonging to the clade Podocnemidoidae. Some of the 22 richest fossil sites of this basin are in the area of Monte Alto, which yielded several squamate, dinosaur, 23 and crocodyliform taxa. Yet, the single turtle reported so far from this area was only briefly described. 24Here, we further describe that specimen, a complete but very crushed shell, as well as a partial skull, both 25 found in outcrops of the Adamantina Formation. Comparison of the shell to other podocnemidoid taxa 26 reveals its affinities to Roxochelys wanderleyi, a turtle originally described from that same stratigraphic 27 unit. The comparative description of the skull and its inclusion in a phylogenetic study, supports the 28 proposal of a new taxon representing a lineage (Peiropemydodda) so far known only from the Marília 29 Formation of the Bauru Basin and the early Paleocene of Bolivia. The digitally reconstructed endocast 30 and inner ear of the new taxon were also described, as not previously done for a fossil pleurodire.31 32

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Abstract. The use of modal tests for detecting damage in reinforced concrete precast slabs is evaluated. A set of eight slabs were tested, each belonging to flats constructed for residential use. Two groups of slabs were identified and, in each group, both cracked and uncracked slabs were found. This made it possible to compare the responses of the slabs when subjected to modal tests. The tests were carried out employing an instrumented hammer and heel drops as excitation sources. Responses were measured using an accelerometer. The lowest natural frequencies of the slabs could be identified and after filtering the results, plots indicating the variation of the lowest natural frequency versus the number of cycles of free decay were obtained for each slab. Such a plot is of more general use than the value of the natural frequency by itself, as it does not depend on slab configuration. It was observed that the cracked slabs presented a similar pattern of variation of the natural frequencies throughout the decay, being distinctive from the pattern observed for their uncracked counterparts. This provided evidence that a quick assessment of the structural condition of such slabs through the use of the tests were feasible.