Design Of Steel Structures Research Articles

Analysis of Flexural Buckling Capacity of Stainless Steel Columns under Axial Compression

In order to provide a basis for the compilation of the bending buckling stability part of axially compressed columns in the technical code for stainless steel structures, the design methods and experimental research data of similar components are collected and compared. The results showed that there are some deficiencies in the current European code for the design of stainless steel structures and the American code for the design of cold‐formed stainless steel structures. According to the collected test data of square tube, rectangular tube, circular tube, elliptical tube, welded H‐shaped steel, and cold‐formed C‐shaped steel for 199 section columns and according to the influence of cold‐formed effect and residual stress on the stability of axial compression members, the members are divided into three categories: A, B, and C according to the section form, in which the columns with cold‐formed square, rectangular hollow section, and lipped C‐section were included in A, columns with circular and oval hollow section were sorted into B, columns with welded H‐section were separated into C, and the three categories of axial compression stability curves are expressed in the form of Perry formula. The comparison with the test data shows that the three kinds of curves can well estimate the stability bearing capacity of members, and the discreteness is small. The reliability of the proposed formula is analyzed, and the results show that its reliability index β meets the requirements of the GB 50068 standard.

Stability Design of Stainless Steel Structures

AbstractThe direct analysis method (DAM), featuring second-order elastic analysis with two stiffness reduction factors (τb and τg), is the primary means of stability design for steel structures in ...

КОНЦЕПЦИЯ ПРОЕКТИРОВАНИЯ СТРОИТЕЛЬНЫХ КОНСТРУКЦИЙ НА ОСНОВЕ ЧИСЛЕННЫХ МОДЕЛЕЙ СОПРОТИВЛЕНИЯ

A large number of theoretical and experimental studies confirms the classical resistance models introduced into standards. However, in modern conditions of rapid improvement of materials and technologies, new original design forms are increasingly being used, for which calculation models have not been established or do not have sufficient confirmation. To overcome these difficulties and due to the high cost of testing, numerical methods of analysis (modeling, simulations) of the behavior of building structures or a separate structural element are becoming increasingly widespread. However, the implementation of the design of steel structures based on numerical models is primarily constrained by the lack of unified approaches to development. There are no verified recommendations on the assignment of parameters of the numerical model, such as the description of steel deformation diagrams, recommendations on the assignment of the dimensions of the final elements, recommendations on the assignment of the shape and values of imperfections, etc. The second important problem is the lack of a safety format and the values of partial factors. The article substantiates the areas of application of the design method based on numerical resistance models, systematizes the factors affecting the uncertainty of the resistance and formulates the necessary stages of development of the design method based on numerical resistance models.

Analysis and Design of Steel Arches/Analyse und Bemessung von Stahlbögen

In the present study, a comprehensive methodology is presented for the analysis and design of steel arches. The method is based on the European Standard for the design of steel structures, using the normative provisions of straight members with appropriate modifications to account for the effects of curvature. In this context, suitable buckling curves of steel arches are employed accounting for reliable residual stress distributions and geometric tolerances. Application of this method is presented for a characteristic case study comprising the steel arches of the entrance canopies in Athens Olympic Sports Complex. The examined structural system is typically encountered in civil engineering applications, consisting of the main arches, the bracing system, the primary/secondary beams, and the foundation.

Bolt Pre-tension Effect on Performance of Bolted Extended End-plate Moment Connections under Cyclic Loading

The most important structural part of steel structures is the connections of the building frame. Tests conducted by the American Steel Institute have led to the introduction of prequalified connections, which is a good reference for designing connections in steel structures. In this paper, four bolted stiffened and unstiffened extended end-plate connections have been studied by numerical analysis with ABAQUS software. In this study, to examine the effect of bolt pre-tension rarely studied, a coefficient of pre-tension force, introduced based on the Iranian Steel Structures Design Regulations as well as the US Steel Design Regulations, has been considered. These connections have been modeled cyclically and in a displacement control manner. The cyclic behavior of the connections, dissipated energy, the resisting moment as well as the stress and strain distribution in the connection have been investigated. According to the results, by creating a pre-tension force in the bolts, the resisting moment of the connection would increase. The rate of growth of this resistance in the unstiffened connections was greater than that of the stiffened connections. The maximum increase in resistance was about 27% for the unstiffened connection and about 25% for the stiffened connection. The dissipated energy for the connections also increased with the increment of bolt pre-tension. The energy dissipation incremental rate was enhanced to a maximum of about 31% for the unstiffened connection and up to a maximum of about 24% for the stiffened connection.

Steel Structures Research Update: Structural Fire Engineering

Across the United States, researchers are making exciting discoveries and advances in structural fire engineering. Eleven of the leading scholars in the field are featured. Brief research highlights are organized by the topic areas of behavior and design of steel and composite structures for fire, fire following earthquakes, and performance-based fire engineering. For each individual, related steel and fire research is also noted. Meanwhile, due to timing and circumstances, there are structural fire engineering researchers who do not appear in this article. You may find some of their structural steel research in past articles or perhaps a future research update.

Lateral-Torsional Buckling Research Needs and Validation of an Experimental Setup in the Elastic Range

The AISC Specification Chapter F I-section member flexural resistance equations are a central part of structural steel design in the United States. The provisions of Sections F4 and F5 address general singly and doubly symmetric I-section members. Analytical studies and experimental tests subsequent to the implementation of these provisions within the 2005 AISC Specification suggest that the corresponding inelastic lateral-torsional buckling (LTB) and tension flange yielding (TFY) resistance equations can be improved, resulting in significantly larger predicted strengths in certain cases and somewhat smaller predicted strengths in other cases. Additional large-scale experimental tests, specifically pushing into the inelastic LTB range, need to be conducted to further investigate these predictions. The broad objective of the additional tests is to achieve a target reliability index of b = 2.6 for building design at a live-to-dead load ratio of 3.0 throughout the design space involving all types of statically determinate I-section flexural members. This paper discusses the need for these tests, specifically focusing on the details of how the test fixtures and bracing systems were configured to minimize incidental restraint, which is a critical consideration when conducting flexural experimental testing. The paper discusses the validation of the testing system by comparison of elastic buckling experimental results to analytical and numerical solutions.

Review of methods for the high-cycle fatigue strength assessment of steel structures subjected to sub-zero temperature

In recent years, there has been a growing interest in exploring the resources of the Arctic regions and an increase in shipping in regions with seasonal sub-zero temperatures. Such low temperatures impose challenging requirements for the structural integrity of steel structures and their weldments. Hence, specific knowledge of the behavior of materials and weldments and how to account for temperature effects is crucial to ensure safe operations. A number of recent studies have shown that fatigue strength at sub-zero temperatures is a major knowledge gap. This is exacerbated by the fact that this effect is not addressed in international standards. In this context, this study presents a comprehensive review of the current state of the art of high-cycle fatigue strength assessment methods for steel structures subjected to sub-zero temperature. The main objective is to provide an overview of how to account for temperature effects on fatigue strength when designing steel structures.

Research on overall stability of BS700 high-strength steel columns with box section

To study the overall stability of BS700 high-strength steel axially compressed columns with box section, the axial compression tests of 10 thin-walled box section columns were conducted in this paper, and the numerical calculation was completed using the finite element method. Moreover, the factor of initial geometric imperfections was considered during the processes of testing and analysis. The test results showed that the failure mode of BS700 high-strength steel columns with box sections was bending buckling. 1/1000 of the member length mentioned in the Code for Design of Steel structures (GB50017–2017) could be used as the maximum initial imperfection. Compared with the curves of the 3c type in the GB50017–2017 and Eurocode specifications, the long-column test results and finite element analysis results were evidently larger and close to those of 3b types in GB50017–2017 and Eurocode 3b (8% larger on average). Moreover, although the ANSI/AISC 360–10 specifications coincided well, this standard tended to be dangerous because it prescribed a relatively low slenderness ratio. Therefore, the curves of the 3b type stipulated in GB50017–2017 and Eurocode were recommended.

GENERATIVE DESIGN OF STRUCTURAL STEEL JOINTS

Structural project is based on technical regulations, structural codes, construction conditions, and client requirements. Through the structural design process, some important decisions that can significantly affect the final result must be implemented. The most important factor for optimal design is the reduction in material and overall work costs. Selecting appropriate joint configurations that can reduce the overall weight and work on the structure is critical. To examine a significant number of possible configurations and their effect on structural behavior, the generative design method (GDM) is used. In this study, software is custom developed, and a relevant example of generative joint structural design is provided. The methodology for the optimal joint and structure design is described comprehensively. The final results show that the GDM is an effective methodology for application in the design of steel structures.

Mechanical Properties of ASTM A572 Grades 50 and 60 Steels at High Temperatures

Studies involving the mechanical properties of high-strength steel (HSS) at elevated temperatures have received considerable attention in recent years. However, current research on HSS at high temperatures is lacking. As a result, the design of fire-protective steel structures with high standards is not sufficiently conservative or safe. This study investigates the effect that elevated temperatures have on the mechanical properties of ASTM A572 Gr. 50 and 60 steels. Reduction factors for the yield strength, tensile strength, and elastic modulus were derived and compared with the standard (AISC, EN1993-1-2) and previous studies (NIST). This study also provides extensive data on the reduction factors for the yield strength, tensile strength, and elastic modulus of mild steel (MS), HSS, and very-high-strength steel (VHSS). The reduction factor for the yield strength was analyzed by expanding the strain level up to 20%. Equations for the yield strength, tensile strength, and elastic modulus were proposed. In future studies, various strains should be analyzed according to the grade of the steel, with the derivation of a reduction factor that considers the plastic strain of the steel. Hence, the findings reported in this study generated a database that can be applied to fire safety design or performance-based fire-resistant design.

Local buckling and hysteretic behavior of thin-walled Q690 high-strength steel H-section beam-columns

To evaluate local buckling and its effect on the hysteretic performance of high-strength Q690 thin-walled H-section beam-columns, cyclic testing was carried out on four H-section columns composed of plates with a nominal yield strength of 690 MPa. Based on China’s standard for the design of steel structures (GB 50010-2017), the four H-section columns are categorized as S4 and S5 sections, and the axial load ratio of the columns is 0.2 and 0.35. After the test, the failure mode, second-order effect of bending moment, hysteresis curve, bearing capacity, backbone curve, energy dissipation, ductility and stiffness degradation of the specimens were investigated. The failure mode of the specimens is elastic–plastic local buckling of the column bottom flange and web. The ductility coefficient of the specimens is 2.08–3.04, and they have certain specific deformation and energy dissipation capacities. Following this, a finite element model was established to simulate the hysteretic performance of the Q690 thin-walled H-section beam-columns. The failure mode and hysteresis curve obtained by the finite element simulation corresponded well with the tests. Based on this agreement, a parametric study was carried out to investigate the influence of the flange width-thickness ratio, web width-thickness ratio, and axial load ratio on the local buckling and hysteretic performance of H-section beam-columns. The variation trend of the backbone curve and the bearing capacity were further investigated by the finite element parametric analysis. Finally, a prediction formula for the beam-column bearing capacity was proposed based on the finite element results. The comparison with the test results shows that the proposed formula has sufficient accuracy and can be used in engineering design.

Influence of Design Parameters on General Stability of Tied Arches with an Upper Bracing

Abstract The paper shows the influence of some design parameters on the general stability of a single-track railway bridge, having the structure made of circular steel arches with rigid vertical hangers. The following structural parameters were considered in this analysis: closed bridge with an upper winding made of horizontal members without links (diagonals) between them; closed bridge, with upper winding made of horizontal elements and ties made in the form of cross diagonals; static scheme of the arch in the transverse direction – hinged, fixed or portal frame. The analysis carried out is based on the normative SR EN 1993-2:2007. Eurocode 3: Design of steel structures. Part 2: Steel Bridges (EC3-2). The results obtained can be useful in the design of the arches structures for the field of bridges or other types of metal structures.

Influence of shear on plastic bending strength of I cross-sections steel beams

In general, steel beams are stressed by bending and shear. Due to the loading a normal stresses σ and shear stresses τ arise in individual cross-sections of steel beams. But they are usually stressed mainly by bending. This follows both from several theoretical analyzes and especially from the corresponding experiments. Therefore, current standards for the design of steel structures allow the impact of shear to be neglected to a certain level of shear stress of the most stressed - decisive cross-sections of beams (EN 1993-1-1, respectively CSN EN 1993-1-1 and others). However, in the case of shorter beams, especially in places of support and in places of application of concentrated forces, the shear effects of the load can also be significant. In the case of more significant shear effects of the load, the plastic flexural strength of the decisive cross-sections and also the overall load-bearing capacity of the steel beams must be adequately reduced. However, the degree of flexural strength reduction with a significant effect of shear in the case of I cross-sections is still unambiguous. It is therefore important to experimentally investigate steel beams in the area of significant shear effects. The presented article contains selected results of experimental investigation of the significant effect of shear on the flexural strength of steel beams I cross-sections.

Analysis Of The Effect Of Bending Strength On Scaffolding System With Direct Analysis Method

Steel scaffolding is a very important component in formwork work to support further work. The purpose of this analysis is to review the maximum compressive strength that occurs in 3-story scaffolding before buckling occurs using the direct analysis method (DAM). The design of steel structures, which are generally slender, requires stability analysis. The result is influenced by imperfections (non-linear geometry) and inelastic conditions (non-linear material). In this final project, we use second-order inelastic analysis based on direct analysis method. The 3-level scaffolding model was analyzed using beam elements in the SAP2000 program with 6 variations of notional loads applied to the weak axis direction of the scaffolding pipe.The lowest compressive strength on 3-story scaffolding before buckling occurs is 18.24 kN with horizontal notional loads to the right on the first level scaffolding, left on the second level scaffolding and to the right on the 3rd level scaffolding. The results of the analysis show that the maximum compressive strength obtained results in a large displacement drastically in the iteration step. By using the analysis on the DAM method, the results obtained are more effective.

A grouping method for optimization of steel skeletal structures by applying a combinatorial search algorithm based on a fully stressed design

In the design of steel structures, optimization methods can find minimum weight solutions. However, the solutions tend to have a high diversity of profiles, thereby raising costs. Grouping methods provide a solution by limiting the number of unique profiles, while still providing an optimal solution. This study proposes a new grouping method and compares its performance to that of existing methods in eight benchmark problems. In current practice, the grouping is mostly performed manually, relying on an engineer’s expertise. This technique requires no additional calculations but fails in finding a light or cheap structure. In general, all other grouping methods perform better than manual grouping. Out of the compared methods, the cardinality constraints method finds the lightest solutions. However, this method requires solving a big optimization problem, thereby increasing computational costs and the variance in the outcome. The new method, ‘the fully stressed combinatorial search’, groups members by a combinatorial search, which evaluates the estimated weight of a restricted set of groupings based on the weight per unit length of the members of a fully stressed design. Subsequently, optimization of a small search space finds the corresponding optimum profiles. These steps are repeated, in which the fully stressed design uses the result of the previous optimization as its reference design. The loop repeats until the grouping is unchanged, or the result becomes less optimal. This new method finds similar results as the cardinality constraints with less finite element evaluations and higher consistency in the results upon repetition of the analysis.

Modeling flexural overstrength factor for steel beams using heuristic soft-computing methods

When evaluating the structural performance of steel moment-resisting frames, significant consideration is given to the flexural behavior of steel beams. This analysis focuses on the primary response parameters, such as the ultimate flexural resistance and rotation capacity that dictate the behavior of the steel beam. In practice, the flexural behavior of steel beams determines the ductile design of steel structures, and a sufficient ductility of steel permits plastic hinge rotations until a full-collapse mechanism is attained. However, it is relatively impossible to guarantee the occurrence of a full-collapse mechanism if the beam’s flexural overstrength is not appropriately quantified by the application of capacity design procedures. Therefore, this study developed analytical formulations to predict the steel beam’s flexural overstrength factor (s) using the multilayer perceptron (MLP)11AMFF: adaptive multilayer feed forward; ANFIS-PSO: adaptive neuro fuzzy system with particle swarm optimization; ANOVA: analysis of variance; GA: genetic algorithm; KKT: Karush–Kuhn–Tucker; LSSVR: least-square support vector regression; M5 Tree: M5 model tree; MAE: mean-absolute errors; MARS: multivariate adaptive regression splines; MLP: multi-layer perceptron; MLR: multiple linear regression; PSO: particle swarm optimization; RBNN: radial basis-function-based neural network; RHS: rectangular hollow section; RMSE: root-mean-square errors; SHS: square hollow sections; SIS: swarm intelligence systems., radial-basis-function-based neural network (RBNN), least-squares support vector regression (LSSVR), adaptive neuro fuzzy system with particle swarm optimization (ANFIS-PSO), multivariate adaptive regression splines (MARS), M5 model tree (M5 Tree), and multiple linear regression (MLR). Numerous cross-sectional geometries were tested with square and rectangular hollow sections, and with I and H sections. The data used for the analysis were sourced from completed experimental studies available in the open literature. The data were categorized as training and testing datasets to develop the models based on the aforementioned methods. For the models, the mechanical properties of the materials, shear length of steel beams, and the geometric properties of the sections constituted the independent variables. Overall, the RBNN demonstrated the best prediction of the steel beam overstrength with a root-mean-square error of 0.099 mm, mean absolute error of 0.066 mm, and a correlation coefficient of 0.825. It was observed that all six machine learning methods provided better estimates than the MLR. The machine learning models developed in this study are expected to serve as a hand tool for engineers and steel structure constructors.

Influence on mechanical behaviors considering construction hosting process of large-scale steel structure

In the design of large-scale steel structure, the design calculation of the structure is usually based on the service state. But in the process of steel structure construction, the displacement and stress produced in the construction process cannot be completely consistent with that in the design state. With the progress of construction process, the deformation and stress caused by self-weight and construction load gradually accumulate until the structure is formed, which will produce construction error relative to the design state. In this paper, FEM method was used to simulate the construction process of the steel grid roof of the theater in the Beijing Sub Center Theater project, and the influence of the accumulated deformation and stress on the mechanical properties of the structure during the construction process was analyzed. The results show that the cumulative deformation and stress in the construction process have a great influence on the final deformation and stress distribution of the structure. The maximum vertical displacement in the actual construction state is 599.6% of that in the design state, and the maximum stress is 119.7% of that in the design state. This will lead to the difference between the construction-completed structure and the design structure, which makes the design result dangerous. The measures to optimize the construction process were also given in this paper, which provides guidance for the construction process of large-scale steel structure.

Lightweight and green design of general bridge crane structure based on multi- specular reflection algorithm

At present, there are some problems that need to be solved in crane steel structure design, such as heavy self-weight of finished structure, high production energy consumption, and huge manufacturing costs. In view of this, a lightweight design method that meets the green product design principle is proposed for crane structure. In this method, an improved new swarm intelligence optimization algorithm named the multi-specular reflection algorithm (M-SRA) is proposed. This algorithm combines the specular reflection algorithm (SRA) with the traditional swarm intelligence optimization algorithm, which has higher computational efficiency. After that, M-SRA is applied to crane steel structure optimization. The results show that the improved algorithm has higher global searching ability and computational efficiency than traditional population intelligence optimization algorithms. The research in this paper provides a reliable design method for the green lightweight design of crane steel structure and a reference for the green design of mechanical products.

Out-of-plane stability design of steel beams by second-order inelastic analysis with strain limits

An accurate and consistent approach to the out-of-plane stability design of steel beams and structures utilising second-order inelastic analysis with strain limits is proposed. The method is implemented using computationally efficient beam elements, with the ultimate structural resistance defined either by (i) the ultimate load factor or (ii) the load factor at which a strain limit, determined on the basis of the continuous strength method (CSM), is attained, whichever occurs first. Thus far, the method has been established for the in-plane design of steel structures and structural components; in the present paper, its scope is extended, for the first time to the scenarios in which out-of-plane stability effects, with a focus on lateral–torsional buckling (LTB), govern. The accuracy and safety of the method are assessed against the results of nonlinear shell finite element (FE) modelling. It is shown that the proposed method consistently provides more accurate results than the traditional LTB design method of prEN 1993-1-1. In addition to its accuracy, the proposed approach also streamlines the design process by eliminating the need for cross-section classification and member design checks.