Resumo em Inglês:

Abstract Approximate seismic evaluation procedures based on the capacity curve have gained wide acceptance in practical engineering owing to their straightforward application and the valuable insights they provide, although they do not always yield results consistent with numerically robust methods. This study presents an investigation into the reliability of results obtained through so-called approximate procedures for constructing the capacity curve, comparing them with those derived from more robust and complex approaches, primarily based on the finite element method. The approximations examined are assessed against results from an experimental study on a full-scale three-dimensional frame tested by another research group, and from a non-linear analysis using the finite element software ATENA, which models the structure under identical conditions. Finally, the study discusses the findings and challenges analysts may face when modelling structures using both numerically refined and approximate procedures, such as those implemented in commercial software like ATENA.

Resumo em Inglês:

Abstract This study presents a systematic investigation of the tensile behavior of FFF-printed PLA specimens, with a specific emphasis on the role of hole fabrication methods—post-drilled versus integrated printed holes—on structural integrity. Unlike prior works that primarily addressed raster orientation and infill effects, this research isolates the influence of hole manufacturing techniques under standardized ASTM D638 and D5766 testing. Stress concentration factors (Kt) were calculated using classical analytical expressions, and their limitations for anisotropic FFF parts are acknowledged and further discussed in the Results and Discussion section. The results revealed that, although raster angle and infill density affected overall strength, the decisive factor was the method of hole generation: post-drilled holes consistently outperformed printed-hole counterparts in tensile resistance and failure behavior. Microscopic analysis confirmed that printed holes introduced interlayer misalignment and shell–infill discontinuities, accelerating crack initiation. These findings demonstrate that hole geometry alone is insufficient to guarantee mechanical reliability, and that the fabrication method of stress concentrators must be considered a critical design parameter in FFF applications.

Resumo em Inglês:

Abstract In this study, two novel machine learning (ML) models, developed using Gene Expression Programming (GEP) and Multi Expression Programming (MEP) algorithms, are proposed for predicting the punching shear capacity of reinforced concrete (RC) slab-column connections with fiber reinforced polymers (FRP) as longitudinal bars. Using the GEP and MEP models, the values of statistical indicators obtained from the training dataset were very close to those values obtained from the testing dataset. In addition, a comparative study was conducted on experimental results and prediction results from the design codes, existing models in the literature and proposed ML models. The comparison revealed that the two models with the highest coefficient of determination (R2) and the lowest mean absolute percentage error (MAPE), root mean square error (RMSE), and coefficient of variation (COV) values belong to the GEP and the MEP model. The results indicated that the proposed GEP and MEP models outperformed the other models in terms of prediction accuracy and robustness. Finally, sensitivity and parametric analyses were conducted.