This paper presents the results of an experimental program developed to investigate the behavior of an innovative technology for connections by adhesion, interlocking and friction in composite structures. Connections have a strategic importance for precast concrete and steel-concrete composite structures, since they determine the global structural behavior and affect the whole production process, from execution to assemblage and other services on site. Currently, however, steel-concrete composite connections are not completely adapted for their use in prefabricated slabs. In this way, the development of new types of connections is clearly necessary, where connections by adherence (or connections by adhesion, interlocking and friction) seem quite promising. To improve the knowledge in the field of connections by adherence, this paper proposes a new geometry of embossments in the steel and in the concrete surfaces associated with the use of a high performance mortar. Monotonic push-out tests are performed, and their results are presented and discussed. A satisfactory behavior of the proposed connection in terms of strength is observed, justifying further studies on the subject.

A análise dinâmica de estruturas é cada vez mais relevante para estruturas civis. Nesse contexto, ensaios dinâmicos, de caráter não-destrutivo, são uma ferramenta promissora, pois permitem que sejam obtidas informações integradas e globais da estrutura a respeito da rigidez e do amortecimento e, além disso, podem ser repetidos e comparados ao longo do tempo. A resposta acústica é uma inovadora metodologia de ensaio não-destrutivo que visa a determinação do módulo de elasticidade do concreto, parâmetro que associado à resistência do concreto à compressão, configura-se como diretriz ao dimensionamento de elementos estruturais de concreto simples, armado ou protendido. Na comparação com metodologias usuais de ensaios não-destrutivos, os resultados demostraram que a utilização de ferramentas baseadas na resposta acústica apresentam diferença inferior a 1% na determinação da frequência de ressonância.

This paper aims to study the concrete dosage conditions for structural purposes in construction sitesl, and the impacts of non-compliance of structural concrete for structural safety, having as study case the city of Angicos / RN. Were analyzed the dynamic elasticity modulus, static elasticity modulus and the compressive strength of concrete samples. Was conducted to collect the survey data, a field research aiming to gather information about dosage of concrete used in the works, as well as the collection of cylindrical specimens of 150 mm diameter by 300 mm of height, prepared according to practice of those professionals. The study indicated a clear necessity to reflection on the subject, since there is no concern, or even, a lack of knowledge by the interviewed professionals regarding the care and procedures necessary for the production of concrete with satisfactory quality, once at least 50% of evaluated construction sites presented compressive strength lower than 20 MPa, minimal strength to structural concrete, as recommended by ABNT-NBR 6118:2014.

Cast in place concrete is often the cheapest solution in the context of conventional construction. However, prefabrication presents advantages in terms of execution time, quality of the structural elements and cost. Thus, the association of precast concrete elements and steel sections in a composite element can result in a high quality structure, executed with greater speed and economy of financial and material resources. Currently, steel to concrete composite connections are not completely adapted to prefabricated slabs and the use of connections by adhesion, interlocking and friction seem quite promising. To improve the knowledge in this field, this paper presents the development of full-scale flexural tests of composite beams using new interfaces for these connections, and their results are interpreted and discussed. For comparison purposes, two beams with cast in place slab are tested. A satisfactory behavior in terms of strength is observed, in both cases investigated (cast in place and precast slab), justifying further studies on the subject.