An Advanced Multicarrier Residential Energy Hub System Based on Mixed Integer Linear Programming

This work proposes a multicarrier energy hub system with the objective of minimizing the economy cost and the CO2 emissions of a residential building without sacrificing the household comfort and increasing the exploitation of renewable energy in daily life. The energy hub combines the electrical grid and natural gas network, a gas boiler, a heat pump, a photovoltaic plant, and a photovoltaic/thermal (PV/T) system. In addition, to increase the overall performance of the system, a battery-based energy storage system is integrated. To evaluate the optimal capacity of each energy hub component, an optimization scheduling process and the optimization problem have been solved with the YALMIP platform in the MATLAB environment. The result showed that this advanced system not only can decrease the economic cost and CO2 emissions but also reduce the impact to electrical grid

Local-overall interactive buckling of welded stainless steel box section compression members

Abstract The interaction between local and overall buckling of welded stainless steel columns has been investigated experimentally and numerically in this study. Eight stainless steel box section compression members were fabricated from slender hot-rolled plates. The material properties and welding residual stress patterns in the test specimens had been obtained previously. Initial geometric imperfections, both local and global, were accurately measured prior to the tests. The test specimens were axially loaded between two pin-ended supports, and both local plate buckling and overall flexural buckling featured visibly in the observed failure modes. Finite element (FE) models were also set up using the ABAQUS software package to conduct numerical simulations, which were initially validated by means of comparison with the experimental data. Using the validated FE models, parametric studies were carried out to assess the influence of the key input parameters, such as the residual stresses, the material strain hardening exponent and non-dimensional proof stress, geometric imperfections and slenderness ratios. Existing design methods, including the design provisions of Eurocode 3 Part 1.4, the design proposal of Rasmussen and Rondal, the direct strength method (DSM) for cold-formed carbon steel and two revisions thereof, were all evaluated against the obtained test and numerical results. It was revealed that the EN 1993-1-4 buckling curves, which do not differ with grade, provide reasonable average strength predictions, but tend to slightly overpredict the local-overall buckling resistances of welded austenitic stainless steel members and slightly underestimate those of duplex stainless steel members. Furthermore, the three considered DSM design curves, all of which were developed on the basis of structural performance data from cold-formed sections, provide generally unconservative strength predictions for welded stainless steel sections. Based on the generated data points, modifications to the current EN 1993-1-4 provisions and the DSM have been proposed, which offer more accurate strength predictions for local-overall interactive buckling resistances of welded stainless steel box section columns

Experimental behaviour of hybrid carbon steel – stainless steel bolted connections subjected to electrochemical corrosion:stainless steel bolted connections subjected to electrochemical corrosion

To minimise cost in practical applications whilst still obtaining a satisfactory performance, stainless steel is often employed in aggressive marine environments to ensure the durability of the structure, whilst parts of the structure less susceptible to corrosion employ conventional carbon steel. When the two materials are in direct contact in the connection region, galvanic corrosion can occur over time thus leading to an increased level of corrosion of the less noble carbon steel parts and an associated degradation in the structural performance. A comprehensive experimental study on the shear behaviour of hybrid carbon steel – stainless steel bolted connections subjected to electrochemical corrosion is presented in this paper. A total of 30 bolted connection specimens were designed and assembled from hot-rolled carbon steel and stainless steel plates. Two bolt grades, the high strength bolts 10.9 and the precipitation hardening stainless steel bolts 10.9 were used to connect the plates. Employing the electrochemical corrosion method, the specimens were subjected to various levels of corrosion by adjusting the duration over which the specimens were sunk in the corrosive medium, which resulted in both different corrosion morphology as well as different levels of mass loss of the carbon steel plates due to corrosion. The corroded connection specimens were thereafter tested to failure under shear exhibiting 4 different failure modes. The load versus deformation curves were recorded and are reported herein, whilst the observed failure modes were also documented. It was revealed that increased level of corrosions led to decreased levels of bolt pretention forces and ultimate resistances of the connections, albeit the severity of the degradation strongly depended on the adopted joint configuration and resulting failure mode

Bending-shear interaction buckling of stainless steel plate girders: numerical investigation and design method

A comprehensive numerical investigation of transversely stiffened stainless steel plate girders under combined bending and shear was carried out in this paper. By using the finite element (FE) software package ABAQUS, numerical models with incorporation of material nonlinearity, initial geometric imperfections and welding residual stresses were developed, and were used to replicate previously obtained test results. The validated numerical models were employed to perform parametric studies to generate structural data points for stainless steel plate girders over a broad range of cross-sectional properties, involving various combinations of bending moment and shear force. The summarised test and FE results were compared with the predicted strengths determined according to European code EN 1993-1-5 and proposals of Jáger et al., Chinese code GB 50017-2017, and American specification ANSI/AISC 370-21, highlighting that the applicability of existing design methods in predicting the ultimate resistances of stainless steel plate girders under combined bending moment and shear force was limited. By referring to the design methods in GB 50017-2017 and ANSI/AISC 370-21, two separate design recommendations were proposed, respectively. Further reliability analyses were performed to verify the applicability of the abovementioned design methods.Peer ReviewedPostprint (author's final draft