Análise teórica e experimental da influência de conectores por aderência em pilares mistos formados por perfis leves e preenchidos com concreto leve

Abstract

Steel-concrete columns are becoming increasingly common in civil engineering due to the efficiency of steel-concrete applications. Their resistance depends on parameters such as the type and thickness of the steel profiles, columns' slenderness, type and concrete strength, among others. Using lightweight profiles as an alternative to hot-rolled ones and lightweight concrete as an alternative to normal-density concrete can help reduce the structure's weight, and thus, evaluating the impact of their use on the performance of the steel-concrete composite systems is necessary. The steel-concrete association aims to extract the maximum capacity of these materials, which can be obtained through the complete materials association. The use of shear connectors can favor the steel-concrete interaction. The present study aimed to evaluate experimentally and theoretically the performance of steel-concrete encased columns made up of lightweight steel profiles and lightweight concrete, with steel-concrete interaction achieved through connections by adherence. Firstly, a systematic review with meta-analysis was developed to evaluate the practical interest of composite columns. Then, direct shear and push-out tests were carried out to evaluate the behavior of the connection by adherence. The composite columns were also tested by means of axial and flexural compression loads. So, after the experimental phase, numerical simulations were carried out using ABAQUS, to extrapolate the results obtained experimentally. The systematic review showed qualitatively and quantitatively practical interest in using composite systems. In the experimental stage, it was observed that the use of shear connectors with ribs favored an increase in the final resistance of the systems by around 14% compared to the models without connectors and around 3% compared to the models with connectors without ribs, indicating that the presence of ribs may have influenced the structural behavior that was observed. Although columns filled with normal-density concrete exhibited higher ultimate strength values compared to those with lightweight concrete, the latter offered a column’s weight reduction of approximately 20%, which is advantageous for prefabrication and construction rationalization. Numerical simulations showed that the use of reinforcement in the columns and the increase in concrete resistance favor the final performance of the systems, going towards normative predictions. Analytical models were calibrated for the proposed interfaces in the analytical stage, which showed good correlations with the results obtained in direct shear tests. Finally, the compression test results of the columns were compared with the expressions in NBR 8800:2008 and Eurocode4, demonstrating good correlations.