FRP RC beams by collected test data: Comparison with design standard, parameter sensitivity, and reliability analyses

Data availability: Data will be made available on request.In the last few years, there has been a significant increase in the utilization of Fiber Reinforced Polymer (FRP) materials as reinforcing elements in concrete structures due to their excellent properties. Unlike traditional steel rebars, FRP rebars do not rust, which helps to prevent degradation and deterioration of the concrete structure over time. This growth has resulted in a rise in the application of design regulations for FRP-reinforced concrete (RC) members. There are currently no European standards that offer suggestions about FRP RC structures. This paper aims to assess the load- carrying capacity and deflection of FRP RC beams with large number of test data available against design standards. The results are compared with ACI 440.1 R-06 specifications and EC2 concepts available in fib Bulletin No. 40. It was found that both ACI and EC2 underestimate the shear flexural capacity. Both design codes presented 38% and 62% of the collected data that overestimated and underestimated the calculation of the deflection, respectively. A parameter influence analysis is performed considering the database collected, and a reliability analysis based on Annex D EN 1990 (2002) is conducted. The reliability analysis allowed suggestion new partial safety factors values of 1.45 and 1.65 for moment and shear capacities, respectively, which can be used by design engineering communities

Five Machine Learning Models Predicting the Global Shear Capacity of Composite Cellular Beams with Hollow-Core Units

Data Availability Statement: The data will be available upon request to the corresponding author.The global shear capacity of steel–concrete composite downstand cellular beams with precast hollow-core units is an important calculation as it affects the span-to-depth ratios and the amount of material used, hence affecting the embodied CO2 calculation when designers are producing floor grids. This paper presents a reliable tool that can be used by designers to alter and optimise grip options during the preliminary design stages, without the need to run onerous calculations. The global shear capacity prediction formula is developed using five machine learning models. First, a finite element model database is developed. The influence of the opening diameter, web opening spacing, tee-section height, concrete topping thickness, interaction degree, and the number of shear studs above the web opening are investigated. Reliability analysis is conducted to assess the design method and propose new partial safety factors. The Catboost regressor algorithm presented better accuracy compared to the other algorithms. An equation to predict the shear capacity of composite cellular beams with hollow-core units is proposed using gene expression programming. In general, the partial safety factor for resistance, according to the reliability analysis, varied between 1.25 and 1.26.National Research Foundation of Korea (NRF) grant funded by the Korea government, (MSIT) (RS-2023-00278784); Inha University Research Grant

Machine learning-driven web-post buckling resistance prediction for high-strength steel beams with elliptically-based web openings

Data availability: Data will be made available on request.Copyright © 2024 The Authors.. The use of periodical elliptically-based web (EBW) openings in high strength steel (HSS) beams has been increasingly popular in recent years mainly because of the high strength-to-weight ratio and the reduction in the floor height as a result of allowing different utility services to pass through the web openings. However, these sections are susceptible to web-post buckling (WPB) failure mode and therefore it is imperative that an accurate design tool is made available for prediction of the web-post buckling capacity. Therefore, the present paper aims to implement the power of various machine learning (ML) methods for prediction of the WPB capacity in HSS beams with (EBW) openings and to assess the performance of existing analytical design model. For this purpose, a numerical model is developed and validated with the aim of conducting a total of 10,764 web-post finite element models, considering S460, S690 and S960 steel grades. This data is employed to train and validate different ML algorithms including Artificial Neural Networks (ANN), Support Vector Machine Regression (SVR) and Gene Expression Programming (GEP). Finally, the paper proposes new design models for WPB resistance prediction. The results are discussed in detail, and they are compared with the numerical models and the existing analytical design method. The proposed design models based on the machine learning predictions are shown to be powerful, reliable and efficient design tools for capacity predictions of the WPB resistance of HSS beams with periodical (EBW) openings

Buckling and Post-Buckling Analyses of Composite Cellular Beams

This paper aims to investigate the buckling and post-buckling analyses of composite cellular beams. For this, the numerical model is calibrated by experimental tests via post-buckling analysis. A parametric study is developed, considering six cross sections. For each section, the opening diameter and web post length are varied. Regarding the buckling analyses for the symmetrical sections, it was concluded that the end post is an important parameter in the strength of composite cellular beams that presents high web slenderness. The smaller the opening diameter, the greater the critical global shear. The variation in the height of the cellular beam had a little influence on larger diameters and web posts widths. Considering asymmetric sections, it was verified that the web post buckling did not happen for the first buckling mode. In this scenario, local web buckling of the upper tee was observed. With the height variation, there was an increase in the global shear. This is due to the fact that with the increase in height, the buckling mode was changed to the WPB, instead of local web buckling. Finally, there was a conservatism in the SCI P355 calculation recommendations, a factor that needs to be revised

Web-post buckling resistance calculation of perforated high-strength steel beams with elliptically-based web openings for EC3

There has been an increase in the use of high-strength steel, as it provides lightweight structural members by satisfying environmental and economic issues. This paper aims to implement high-strength steels in the web-post buckling resistance equation, which was based on the truss model according to EUROCODE 3, presented previously by the authors. For this task, a finite element model is developed and employing geometrically and materially nonlinear analysis with imperfections. A parametric study is carried out, considering the key geometric parameters that influence the web-post buckling resistance. Three high-strength steel grades are studied (S460, S690 and S960) and in total, 13,500 finite element models are processed. A new factor for adapting high-strength steels to the equation proposed previously was presented. The statistical parameters calculated, via the ratio between the numerical and analytical models, considering the regression, mean, standard deviation and variance, were 0.9817, 0.985, 8.29% and 0.69%, respectively. In conclusion, a reliability analysis was presented based on Annex D EN 1990 (2002)