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This paper provides universal structural design criteria for heavy industrial projects. Structural design requirements for pipe racks, steel modules, modularized equipment skids, vertical and horizontal vessel supports, and vibrating equipment foundations are discussed. An overview of loading mechanisms of various systems is provided for operational, testing, and lifting conditions. Design recommendations are provided for permanent and removable structures. Several structural idealization concepts are also proposed to ensure accurate load transfer. The theoretical basis and the merits of various methods used in the practice are also discussed. Industrial design examples are provided including multilevel pipe rack and pump foundations. The paper overviews and pieces together the engineering requirements for critical structures that are encountered in heavy industry. [ABSTRACT FROM AUTHOR]

The application of Topology Optimisation (TO) to help in the manufacture of metallic components in highly technological industries has increased recently. To equally benefit from TO, the construction industry must address its specific issues, such as adherence to code requirements and challenges in using cutting-edge software packages in complex joints with non-linear behaviour. To assist in such a challenge, the current study offers a methodology proposal to synthesise code and structural behaviour requirements into geometrical constraints for the optimisation problem of laminar steel parts under compression while integrating Non-linear Finite Element Analyses (NLFEA) that ensure the safety of the solution. It has been found that, for a real case-study, the initial volume of a connection's cover-plate can be decreased by up to 40% while maintaining the connection's original capacity and that a 30% volume decrease may be achieved while keeping the original plate capacity. In both cases, the plate's ultimate deformation capacity was enhanced. Evidence has been found that Linear Elastic TO may not provide safe-sided solutions for parts with an intrinsic non-linear behaviour. With the attained volume reductions, less raw materials may be consumed, assembly and transportation will be facilitated, and the goals of the sector's decarbonisation, energy intensity and sustainability will be favoured. [ABSTRACT FROM AUTHOR]

In this work, Non-penalisation Smooth-Edged Material Distribution for Optimising Topology (np-SEMDOT) algorithm was developed as an alternative to well-established Topology Optimisation (TO) methods based on the solid/void approach. Its novelty lies in its smoother edges and enhanced manufacturability, but it requires validation in a real case study rather than using simplified benchmark problems. To such an end, a Sheikh-Ibrahim steel girder joint's tension cover plate was optimised with np-SEMDOT, following a methodology designed to ensure compliance with the European design standards. The optimisation was assessed with Physical Nonlinear Finite Element Analyses (PhNLFEA), after recent findings that topologically optimised steel construction joint parts were not accurately modelled with linear analyses to ensure the required highly nonlinear ultimate behaviour. The results prove, on the one hand, that the quality of np-SEMDOT solutions strongly depends on the chosen optimisation parameters, and on the other hand, that the optimal np-SEMDOT solution can equalise the ultimate capacity and can slightly outperform the ultimate displacement of a benchmarking solution using a Solid Isotropic Material with Penalisation (SIMP)-based approach. It can be concluded that np-SEMDOT does not fall short of the prevalent methods. These findings highlight the novelty in this work by validating the use of np-SEMDOT for professional applications. [ABSTRACT FROM AUTHOR]

The Van Brienenoord Bridge is a large bridge which includes three movable bascules. The two oldest bascules stem from 1965. A study into renovation and/or replacement of these bascules has been performed and replacement was deemed necessary. A new design for the mechanical driving system has been made, where the design of the western bascule served as starting point. The regulations and requirements have become more stringent since 1965, however the available space is restricted by the existing concrete structure. A steel rack and pinion design is chosen as the best option for the mechanical driving system. In the design of the steel rack, several considerations have been made with respect to the material choice. A fully welded construction was desired due to the lower weight of the construction. However, stringent requirements are made with respect to the hardness, yield strength and tensile strength in several locations of the rack. After considerable calculations and consulting suppliers/manufacturers the tooth rack will be made of 25CrMo4 as the best compromise between material properties and weldability. The pinion material is selected as 34CrNiMo6 since weldability is not an issue. The choice here has to do with the minimum required mechanical properties (even above‐normative refinement). The connection to the concrete structure consists of an eye which is rather big and bulky. This is considered to be rather conservative due to the calculations methods and leaves room for optimisation. [ABSTRACT FROM AUTHOR]

The field of structural engineering can be augmented with advanced data analysis techniques. Structural engineering applications consist of datasets which may include experimental or/and computational data, and can be used to derive design provisions based on the measured data. Cluster analysis is a data exploration technique that involves identifying groups in a dataset and providing relationships between input parameters, which could supplement existing engineering intuition and knowledge. As a test case, this paper reanalyzes the existing test data for shear connectors using a cluster analysis. A database of push‐out tests was established from the literature, which was then sorted into subsets using two methods: (1) manual grouping based on engineering judgment and (2) Gaussian mixture models that detect clusters based on relationships between parameters in the data. The recommended data groupings based on the two methods were compared. Reliability analyses were conducted on each data subset to determine the recommended resistance factors. The results were compared to the resistance factors prescribed in the AISC 360‐22 Specification, which now permits a performance‐based alternative for the shear connector design. [ABSTRACT FROM AUTHOR]

This paper describes effective design procedures and identify construction challenges encountered in mega revamp projects. Lessons learned through the execution of these projects are discussed. The paper fills existing gaps and pieces together engineering requirements for critical structures that are used in heavy industry. Numerical and simplified analytical models are provided to assist the engineers to model load transfers with reasonable accuracy. An overview of loading mechanisms of various systems is also provided for operational, testing and lifting conditions. Industrial examples are provided for steel modules, pipe racks, and equipment support systems. The procedures presented in the paper are computationally efficient and can be implemented in practice. The theoretical basis and merits of various methods used in the practice are also discussed. [ABSTRACT FROM AUTHOR]

In this work, Non-penalisation Smooth-Edged Material Distribution for Optimising Topology (np-SEMDOT) algorithm was developed as an alternative to well-established Topology Optimisation (TO) methods based on the solid/void approach. Its novelty lies in its smoother edges and enhanced manufacturability, but it requires validation in a real case study rather than using simplified benchmark problems. To such an end, a Sheikh-Ibrahim steel girder joint’s tension cover plate was optimised with np-SEMDOT, following a methodology designed to ensure compliance with the European design standards. The optimisation was assessed with Physical Nonlinear Finite Element Analyses (PhNLFEA), after recent findings that topologically optimised steel construction joint parts were not accurately modelled with linear analyses to ensure the required highly nonlinear ultimate behaviour. The results prove, on the one hand, that the quality of np-SEMDOT solutions strongly depends on the chosen optimisation parameters, and on the other hand, that the optimal np-SEMDOT solution can equalise the ultimate capacity and can slightly outperform the ultimate displacement of a benchmarking solution using a Solid Isotropic Material with Penalisation (SIMP)-based approach. It can be concluded that np-SEMDOT does not fall short of the prevalent methods. These findings highlight the novelty in this work by validating the use of np-SEMDOT for professional applications.

In the present paper an improved formulation devoted to the optimal design problem of a special moment resisting connection device for steel frames is proposed. This innovative device is called a Limited Resistance Plastic Device (LRPD) and it has been recently proposed and patented by some of the authors. It is thought to be preferably located at the extremes of the beam, connecting the beam end cross section with the relevant column. The typical device is a steel element characterized by symmetry with respect to three orthogonal barycentric planes and constituted by a sequence of three portions with abrupt cross section changes. The main novelty of the present proposal is related to the design of special geometry for the optimal device ensuring that it possesses a reduced resistance with respect to the relevant connected beam element, is characterized by an equivalent bending stiffness equal to the one of the connected beam elements and exhibits full plastic deformations avoiding any local instability phenomenon. The optimal design is formulated as a minimum volume one and is subjected to suitable constraints on the geometry of the device and on its elastic and plastic behavior. The optimization problem is a strongly non-linear programming one and it is solved by adopting an interior-point algorithm that is available in the MATLAB Optimization Toolbox. The numerical simulations are devoted to the most used standard steel profiles (IPE, HE) and the results prove the great reliability of the proposed device. In addition, the relevant elastic and plastic domains of the designed devices are defined, and the expected behavior of the device is verified by appropriate 3D finite element models in the ABAQUS environment. [ABSTRACT FROM AUTHOR]

The mechanical behaviour and design of fixed‐ended steel equal‐leg angle section members subjected to axial compression are addressed in this study. First, the critical buckling behaviour is described. Experimental data on steel equal‐leg angle section columns collected from the literature are then used for the validation of numerical (shell finite element) models, developed within the commercial package ABAQUS. Validation is performed by means of comparisons between the test and numerical results, considering ultimate loads, failure modes and the load‐deformation responses, all of which are shown to be generally in good agreement. A numerical parametric study is then presented considering steel angle section columns with a wide range of slenderness values. The behaviour and load‐carrying capacity of the columns is shown to be dependent on, not only the column slenderness, but also the ratio of the elastic torsional‐flexural buckling load to the elastic minor‐axis flexural buckling load. Finally, the collected experimental and generated numerical results are used to develop a new design approach for fixed‐ended steel equal‐leg angle section columns, reflecting the observations made. The proposed approach offers improved accuracy and consistency in strength predictions compared to the existing codified design rules. [ABSTRACT FROM AUTHOR]

Topology Optimisation is a broad concept deemed to encapsulate different processes for computationally determining structural materials optimal layouts. Among such techniques, Discrete Optimisation has a consistent record in Civil and Structural Engineering. In contrast, the Optimisation of Continua recently emerged as a critical asset for fostering the employment of Additive Manufacturing, as one can observe in several other industrial fields. With the purpose of filling the need for a systematic review both on the Topology Optimisation recent applications in structural steel design and on its emerging advances that can be brought from other industrial fields, this article critically analyses scientific publications from the year 2015 to 2020. Over six hundred documents, including Research, Review and Conference articles, added to Research Projects and Patents, attained from different sources were found significant after eligibility verifications and therefore, herein depicted. The discussion focused on Topology Optimisation recent approaches, methods, and fields of application and deepened the analysis of structural steel design and design for Additive Manufacturing. Significant findings can be found in summarising the state-of-the-art in profuse tables, identifying the recent developments and research trends, as well as discussing the path for disseminating Topology Optimisation in steel construction. [ABSTRACT FROM AUTHOR]

The importance of connections in steel structures is paramount, not only because it greatly influences the cost of construction and provides room for innovations, but also due to the connections’ impact on global structural behaviour. Therefore, research into innovative connections for seismic applications and related design criteria has significantly grown in recent years. However, it has been pursued mostly on local—connection or frame—levels, leaving the system analysis and code compliance levels with a meagre investigation. Moreover, less than 1% of published papers concerning steel connections and earthquake engineering are review articles. To overcome this gap, this systematic review of more than 240 references, including scientific contributions and design codes in the field aimed to cover both recent research and current shortcomings in practice and regulations. It has been found that European design rules updated to a fully performance-based design philosophy is imminent and is deemed to bring pre-qualified joints and increased complexity. Design rules have been systematized, and current hindrances have been highlighted. A deeper look into research needs and trends showed that investigations in connections for concentrically X braced frames are still a necessity, while developments in self-centring and replaceable connections as well as in simple solutions for increasing damping are expected to modify how joints are designed, as soon as semi-rigid and partial strength connections are more easily allowed by design codes.

This paper describes a method for teaching design topics. While the example is for a Design of Steel Structures course with no grader or TA support, the methods and concepts are adaptable for a wide range of design courses and formats. The objective is to provide approaches for students of varying learning styles to internalize design concepts andprovide confidence in their ability to complete designs of an overall structure rather than individual components. A unique component implemented to address this is a reference structure interleaved into course content throughout the semester. [ABSTRACT FROM AUTHOR]

In the present paper an improved formulation devoted to the optimal design problem of a special moment resisting connection device for steel frames is proposed. This innovative device is called a Limited Resistance Plastic Device (LRPD) and it has been recently proposed and patented by some of the authors. It is thought to be preferably located at the extremes of the beam, connecting the beam end cross section with the relevant column. The typical device is a steel element characterized by symmetry with respect to three orthogonal barycentric planes and constituted by a sequence of three portions with abrupt cross section changes. The main novelty of the present proposal is related to the design of special geometry for the optimal device ensuring that it possesses a reduced resistance with respect to the relevant connected beam element, is characterized by an equivalent bending stiffness equal to the one of the connected beam elements and exhibits full plastic deformations avoiding any local instability phenomenon. The optimal design is formulated as a minimum volume one and is subjected to suitable constraints on the geometry of the device and on its elastic and plastic behavior. The optimization problem is a strongly non-linear programming one and it is solved by adopting an interior-point algorithm that is available in the MATLAB Optimization Toolbox. The numerical simulations are devoted to the most used standard steel profiles (IPE, HE) and the results prove the great reliability of the proposed device. In addition, the relevant elastic and plastic domains of the designed devices are defined, and the expected behavior of the device is verified by appropriate 3D finite element models in the ABAQUS environment.

Increasing requirements concerning the operational conditions and durability of tools create a demand for the optimization of tool steels. High‐speed steels (HSSs), for example, contain high amounts of carbides embedded in a secondary hardenable martensitic matrix. The wear behavior and the mechanical properties of HSS can be optimized for a certain application by adjusting the type and amount of carbides, as well as their compositions and the composition of the matrix. Computational thermodynamics based on the calculation of phase diagrams method allow the estimation of arising phases as well as phase compositions during the solidification or the heat treatment of a steel. However, in complex alloy systems, for example, HSS, the relationships between the content of alloying elements and the stability and the composition of phases can be complicated and nonlinear. Therefore, it can be difficult to find alloy compositions that are suitable to achieve a desired microstructure with iterative calculations. To handle this difficulty, a computational tool is developed, which determines compositions to obtain predefined HSS microstructures. The computational tool is based on a neural network that was previously trained with a thermodynamically calculated database. The efficiency of this approach is experimentally verified by producing and investigating laboratory melts of different HSS. [ABSTRACT FROM AUTHOR]

The successful and effective shaping of curvilinear steel bar structures is becoming an increasingly complex and difficult task, due to the growing demands to satisfy both economic and environmental requirements. However, computer software for algorithmic-aided design makes it possible to take into account many aspects affecting structures, as early as the initial design stage. In this context, the paper presents an optimization method for shaping the curvilinear steel bar canopies of hyperbolic paraboloid and cylindroid shapes, in order to obtain effective structures adapted to external environmental conditions. The best structural solutions in terms of the structure’s shape, topology and support positions are obtained as the effects of multi-criteria optimizations with the application of genetic algorithms. The following are used as the optimization criteria: minimal structure mass and minimal deflections of the structure’s members, as well as their maximal utilization. Additionally, the best canopy locations in relation to the sides of the world are determined through analyzing their shadow casts for various locations, so the structures have the least impact on the surroundings. This research, with its interdisciplinary character, aims to present the possibility of applying generative shaping tools to obtain structurally effective and environment-adaptive curvilinear steel bar structures in the first phase of their design, which can support sustainable designing.

Topology Optimisation is a broad concept deemed to encapsulate different processes for computationally determining structural materials optimal layouts. Among such techniques, Discrete Optimisation has a consistent record in Civil and Structural Engineering. In contrast, the Optimisation of Continua recently emerged as a critical asset for fostering the employment of Additive Manufacturing, as one can observe in several other industrial fields. With the purpose of filling the need for a systematic review both on the Topology Optimisation recent applications in structural steel design and on its emerging advances that can be brought from other industrial fields, this article critically analyses scientific publications from the year 2015 to 2020. Over six hundred documents, including Research, Review and Conference articles, added to Research Projects and Patents, attained from different sources were found significant after eligibility verifications and therefore, herein depicted. The discussion focused on Topology Optimisation recent approaches, methods, and fields of application and deepened the analysis of structural steel design and design for Additive Manufacturing. Significant findings can be found in summarising the state-of-the-art in profuse tables, identifying the recent developments and research trends, as well as discussing the path for disseminating Topology Optimisation in steel construction.

A state‐of‐the‐art framework for design of jacket foundations for offshore wind turbines is presented. It is illustrated how an efficient, yet highly accurate structural model can be achieved by a combination of a comprehensive beam finite element model and more detailed shell/solid finite element models, where the former suffices for representing the overall global behaviour, while the latter improve the representation of non‐trivial structural details such as the transition piece and tubular joints. Hereby the verification of the majority of the structural elements according to various design codes can be automated on beam element level, while the fatigue performance via the hot‐spot method as well as detailed stress and buckling analysis for relevant joints and details can be performed based on the detailed shell/solid finite element models readily available for stiffness representation. This computational framework ensures consistency between the local and global description levels and an efficient cloud interface facilitates the thousands of design load cases that typically requires consideration for a full detailed design to be simulated within a reasonable amount of time. [ABSTRACT FROM AUTHOR]

When designing class 4 steel sections in accordance with EN1993‐1‐5, two different methods are proposed; The Effective Section Method (ESM) and the Reduced Stress Method (RSM). The ESM is generally known for leading to results closest to the post‐buckling capacity, with the RSM considered more conservative. The RSM is much more general though, and a combination formula is present for combining longitudinal stresses, transverse stresses and shear stresses, whereas a suitable combination formula is not available for the ESM. In connection with the steel design of the orthotropic composite deck on the Queensferry Crossing, an investigation into the suitability of the ESM was made. This, as it was believed that the use of this method would lead to the most cost‐efficient design. The Queensferry Crossing (1) has stay cable planes positioned near the middle of the deck, leading to a transverse continuous compressive stress in the bottom steel plate. As EN1993‐1‐5 (2) does not provide a method for combining longitudinal stresses with continuous transverse stresses when using the ESM, a need for a suitable combination formula was evident. In this paper a combination formula for combining longitudinal stresses, uniform transverse stresses and shear stresses in an orthotropic steel panel using the ESM is proposed. A typical panel from the Queensferry Crossing is used, when results from the ESM and RSM are compared for various stress distributions, with results from a fully non‐linear FE shell model. A good relation between the ESM and the fully non‐linear FE shell model is found, when the combination formula is used, and it is shown that significant savings to the steel quantities can be made by utilizing this combination formula. [ABSTRACT FROM AUTHOR]

Abstract Flexural and flexural-torsional buckling are stability phenomena and the controlling limit state for carbon steel angle columns. When these columns are made of austenitic stainless steel, some structural response differences are expected and motivated the present investigation. In fact, the stainless steel grade has been investigated in last few years due to unique proprieties in comparison with the carbon steel grades. Therefore, this paper aimed to enlarge the available experimental data for austenitic angles under compression. To fulfil these objectives, thirteen specimens were tested on 64 × 64 × 6.4 hot rolled equal-legs angles with lengths varying from 250 mm to 1500 mm. A numerical study has been developed comparing the results with experimental tests. In addition, a parametric analysis was performed where the slenderness and cross sections ranges were expanded to investigate their influence on the structural behaviour. These results were compared to Eurocode 3 part 1–4 and enabled the suggestion of better-suited values for the adopted Eurocode column curve parameters λ 0 and α, respectively. Highlights • An experimental programme involving stainless steel hot-rolled angles was performed. • A numerical model was calibrated against experimental results. • Flexural and local buckling ultimate limit states were investigated. • A new buckling curve was proposed based on Eurocode 3, part 1–4 procedures. [ABSTRACT FROM AUTHOR]

Critical temperature is defined as the temperature at which failure is expected to occur in a structural steel member given a uniform temperature distribution and load level. Determination of the critical temperature is a simple but efficient way for structural fire design. This paper proposed a new model which incorporated the buckling, load levels and non-dimensional slenderness to calculate the critical temperature of steel member under fire based on the simple calculation models in Eurocode 3. To advance the application of this new model, design charts for determining the critical temperatures were developed. The design charts showed that the critical temperature decreases with increasing load level, and increases as the buckling curve varies from 'a' to 'd'. It is also recommended to use higher grade steel in both normal and fire situations. The accuracy of this model was ascertained by comparing with the test results in available literature. The new model gave an average prediction-to-test ratio of 0.980 with a standard deviation of 0.077, indicating conservative and less scattered predictions. The percentage of over-prediction (i.e., prediction-to-test ratio >1.0) was less than 5.8% when the nominal yield strength of steel rather than its test strength was used for predictions. In general, reasonable agreements were obtained between the test results and the predictions. [ABSTRACT FROM AUTHOR]

Target structural reliabilities are implicit in most modern design codes and yet efficiency of design and construction as well as the presence of constraints on the design space mean that structural components in a building system may have as-designed reliabilities that differ from the target reliabilities. This paper presents an investigation of this phenomenon through a detailed examination of the two story cold-formed steel framed building designed and tested as part of the CFS-NEES project and seeks to use this case study to elucidate features of the component and system reliabilities that may prevail in typically designed buildings. Specifically, for the gravity load system of the second floor and the lateral force resisting system the demand to capacity ( D / C ) ratios and reliabilities ( β ) are calculated. The results of these calculations illustrate the excess and highly variable D/C ratios and reliabilities that result from efficient design procedures. Since the ultimate goal of structural design is to ensure performance of the structural system at a target level of reliability the influence of excess and variable component reliability on reliability of the lateral force resisting system is examined by making assumptions about series and parallel-type interaction of the floor diaphragm and shear walls. Finally, discussion is presented about the role of load combinations and their associated coefficients of variation in determining component and system reliability in a cold-formed steel framed building. Future considerations include more robust, high fidelity, modeling of the system effects and evaluation of excess capacity and variability of reliability across suites of other building designs and structural systems such as roof trusses. [ABSTRACT FROM AUTHOR]