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• Finite element model of stainless steel perforated beam at high temperatures was developed. • Finite element analysis of 400 perforated beams was carried out. • The numerical specimens were subjected to temperatures from 22 - 900 ºC. • Various existing design rules were assessed by compared with 400 numerical data. • Design rules are recommended for stainless steel perforated beams at elevated temperatures. Steel structures are often used in buildings due to their advantage in weight-to-strength ratio. However, their structural capacity deteriorates in fire as the temperature of the structures rises. Investigation of cold-formed stainless steel (CFSS) structures at elevated temperatures is still limited, especially for rectangular hollow section (RHS) beams having a single web hole in the mid-span (perforated web). Therefore, a numerical investigation was conducted to evaluate the current design provisions to calculate the strength of such beams at elevated temperatures ranging from 22 - 900 °C. A total of 400 specimens of stainless steel grades austenitic (EN 1.4301) and lean duplex (EN 1.4162) were considered. The investigation used finite element analysis (FEA) to simulate the behaviour of RHS beams with perforated web under pure bending. The finite element (FE) model was validated against a series of experimental results available in literature. The comparison between flexural strengths obtained from FEA with design values calculated from the current design rules showed that the design rules are conservative. However, they are not always reliable and safe for RHS beams without and with a perforated web for the two material grades at elevated temperatures. In this study, only the design rules specified by Eurocode 3 are shown to be reliable and safe. [ABSTRACT FROM AUTHOR]

• Four point bending tests were conducted on 18 ferritic stainless steel perforated beams. • Finite element model was developed and validated against experimental results. • Parametric study with 146 specimens was performed. • The influence of hole size and section geometry on flexural capacity has been evaluated. • Direct strength method for flexural capacity prediction was assessed. Ferritic stainless steel has been increasingly used in construction industry due to its excellent mechanical properties and a relatively low price compared with other grades of stainless steel materials. Experimental and numerical investigation was performed to examine the structural behavior of ferritic stainless steel perforated beams. The experimental program consisted of twenty specimens of rectangular hollow sections subjected to four-point bending, based on which finite element model has been developed for further parametric study. The influence of hole size and section slenderness on the test and numerical specimens was evaluated. It was shown that moment capacity and curvature at ultimate moment had negligible effect for specimens with hole diameter up to 20% of web depth, but reduced when hole size beyond 20% of web depth in this study. The section slenderness of perforated beams was found to have little influence on reduction of moment capacity for the hole diameter up to 70% of web depth. The test and numerical results were also compared with design strengths predicted by the current direct strength method for cold-formed carbon steel perforated beams. It was shown that the current design rules provide conservative predictions to the cold-formed ferritic stainless steel perforated beams. In this study, modified design rules based on the direct strength method were proposed, and shown to improve the accuracy of these design rules in a reliable manner. [ABSTRACT FROM AUTHOR]

The present work investigates structural response of tidal stream turbine blades subjected to impact loads from sea animals. A full-scale tidal turbine blade model was developed using a finite element modelling software ABAQUS, while a simplified geometry of an adult killer whale (Orcinus orca) was assumed in simulating impact on the blade. The foil profiles along the turbine blade were based on the NACA 63-8XX series, while the geometric and material properties of the sea animal were calibrated with experimental results. The numerical model simulated the dynamic response of the blade, accounting for radial velocities of the blade corresponding to real life scenarios. Different magnitudes and trajectories of the velocity vector of the sea animal were simulated, in order to investigate their influence on the turbine blade's plastic deformation. Furthermore, multiple impacts were analysed, in order to monitor the accumulation of plastic strain in the material of the blade. Finally, the potential application of stainless steel material in tidal stream turbine blades for impact resistance was evaluated, through comparison of numerical results obtained from models using stainless steel and mild carbon steel materials. [ABSTRACT FROM AUTHOR]

• The thermal-mechanical behavior of the CHS T-joints with a welded collar plate under load, including the evolution laws of temperature field, strain, and displacement, is elucidated. • The welding residual effects on the CHS T-joints reinforced with a collar plate under load are revealed, where the thermal expansion and contraction deformation induced by high temperature dominates. • The applicability of existing specifications' strength reduction factors for the CHS T-joints reinforced with collar plate under load is discussed. • Size recommendations for the compressive strength of the CHS T-joints reinforced with collar plate under the chord preload are presented. The paper presents a comprehensive test program on collar plate reinforced CHS T-joints under different preload conditions, in order to investigate the effect of preload and welding thermal on reinforced joints. A total of four specimens, including specimens with and without preload when the collar plates were welded, were tested under brace axial loading. The test results, including welding temperature field, development of strain as well as welding residual deformation during the welding process are measured and presented in this paper. Furthermore, the failure model and compressive strength of the collar plate reinforced T-joints were determined. The test results demonstrated that the localized high temperature and rapid attenuation are the characteristics of the welding temperature field, which instantaneous peak temperature rose to 1808 °C at the local area and attenuated to 600 °C in an elliptic range of about 3.1 cm × 1.7 cm. The failure modes of collar plate reinforced CHS T-joints do not change with preload on the chord and welding thermal. Furthermore, preload on the chord reduces the compressive strength of reinforced joints. The strain distribution and residual deformation are affected by the thermal expansion and cold shrinkage, while the development of the welding temperature field is not affected by the preload. Finally, for compressive strength of CHS T-joints reinforced with collar plate by welding, the applicability of the reduction coefficient due to preload calculated by existing codes was assessed by comparing design values with experimental results. A finite element model by ANSYS, considering the welding heat, was established. Key parameters affecting the strength of the T-joint at the reinforced collar plate under load were identified through parametric study with finite element models. Construction recommendations of welded CHS T-joints are proposed. [ABSTRACT FROM AUTHOR]

• Residual stresses and deformations of I-section curved beams with different curvatures were measured using the cutting strip and novel 3D scanning methods, respectively. • Welding process of the I-section curved beam was precisely simulated using the finite element method. • Effects of the welding sequence, welding speed, and curvature on the residual mechanical properties of the welded I-section curved beams were investigated. • Reasonable welding sequences, welding speeds, and curvatures of the I-section curved beams were recommended. This paper presents an experimental and numerical investigation on welding-induced residual stresses and deformations of in-plane curved welded I-section steel beams. Two welded curved beams with different curvatures were investigated. After welding the curved beam, the residual deformations were measured by a 3D scanner. The residual stresses were subsequently obtained through a high-precision sectioning method. The effects of curvature on the magnitude and distributions of residual deformations and stresses at the specific sections were analysed with the test results. It was found that the residual deformation gradually increased from the weld region to both ends of the flange plate, and the torsion in the web plate became severe with a decrease in curvature of the curved beam. Moreover, the welding process of the curved beam was simulated using the finite element (FE) method. The developed FE model was validated against the test results, and thereafter, parametric analyses were conducted to assess the influence of welding sequence, welding speed, and curvatures of the curved beam on the welding residual stresses and deformations. The numerical results demonstrated that the residual stresses and deformations were significantly influenced by welding speeds, but the influence from curvature of the curved beam was relatively small. Finally, a reasonable welding sequence, welding speed, and curvature of the curved beams were recommended. [ABSTRACT FROM AUTHOR]