3D Steel Frames Research Articles

Component tests and numerical simulations of 3D steel frame structures for progressive collapse

This paper presents a comprehensive study on three-dimensional steel frame structures subjected to progressive collapse, drawing insights from a full-scale steel frame substructure test. The investigation encompasses connection component tests and numerical simulations, focusing on extended end plate and double-angle cleat connections employed in the substructure test. The mechanical properties of the connection components were tested, forming a basis for defining component properties in subsequent connection models. Finite element (FE) models of the test substructure were developed, utilizing hybrid elements for the steel frame part, which include beam, connector, and spring elements based on the component method. To simulate reinforced concrete slabs, a combination of refined solid elements and simplified shell elements was employed. The former accurately captures detailed failure modes, while the latter efficiently simulates the collapse behavior of large-scale steel frame structures. Validation of the established models against test results encompassed load-displacement responses, internal forces in structural members, and failure modes. The validated FE models were then utilized to analyze and discuss the contributions of various structural components in resisting progressive collapse. Specific focus was placed on the development of load-resisting mechanisms in the floor slab and the influence of beam-column connection types on structural behavior. The paper explores the role of bracing systems in a building in resisting progressive collapse. Additionally, it evaluates the effectiveness of the restraint systems used in the test, shedding light on their ability to accurately reflect real restraint effects from the surrounding structure. The findings presented herein contribute valuable insights to the understanding of progressive collapse behavior in steel frame structures, with implications for robustness design of multi-story steel buildings.

A convolution neural network-based technique for health monitoring of connections of a multi-story 3D steel frame structure

A convolution neural network-based technique for health monitoring of connections of a multi-story 3D steel frame structure

Probabilistically modelled geometrical imperfections for reliability analysis of vertically loaded steel frames

The article explores the stochastic modelling of 3D steel frames under static vertical load, with a main focus on random initial geometrical imperfections. The random input parameters for initial geometrical imperfections are derived from the tolerance criteria in accordance with European standard. In order to derive statistical parameters from the corresponding standard tolerances, two methods noted as #RSS (random storey sway) and #RSP (random storey position) have been utilized and compared. Both of these methods are used along with the first-order reliability method (FORM) and the advanced finite element method (FEM) – geometrically and materially nonlinear imperfect analysis (GMNIA) to numerically analyse several geometries of steel frame structures. Ultimate resistances of these structures are monitored and basic sensitivity studies are conducted. The results are also compared with the deterministic approach of the European standard. The stochastic approach of the FORM to estimate the ultimate resistance of steel frame structures serves as a verification tool of the classic, in engineering praxis widely used, deterministic approach. This study provides useful provisions for the advanced numerical analyses of steel frames of various geometries. Additionally, the estimations of ultimate resistance by the deterministic European standard approach is verified for selected frame geometries.

Probabilistic study and numerical modelling of initial geometric imperfections for 3D steel frames in advanced structural analysis

Initial geometric imperfections, including member out-of-straightness and frame out-of-plumb, shall be accounted for in the system-based design-by-advanced analysis of steel frames. The effect of considering initial geometric imperfection in planar frames using advanced analysis has been studied using different methods, such as notional horizontal load and direct modelling of imperfections. However, modelling initial geometric imperfections for 3D frames presents additional challenges because the imperfection is spatial and may involve torsion, with random magnitude. This paper presents a procedure for modelling initial geometric imperfections of three-dimensional frames composed of cold-formed hollow structural sections (HSS) or hot-rolled steel I-sections. For I-section steel frames, the linear combination of buckling modes method (LCBM) is used to model the imperfections, and the appropriate number and amplitudes of elastic buckling modes are proposed for sway frames and braced frames. For HSS frames, the notional horizontal load method (NHL) is applied to sway frames, and the corresponding load factors are presented. The LCBM is applied to braced HSS frames, and the scale factors for selected buckling modes are suggested. Moreover, advanced geometric and material nonlinear analyses are conducted on illustrative examples to verify the proposed simulation approach.

Collapse probability and resistance factor calibration of 2D steel frames under gravity loads

Collapse probability and resistance factor calibration of 2D steel frames under gravity loads

Experimental assessment of an asymmetric steel–concrete frame under a column loss scenario

Several noteworthy accidents clearly pointed out the risk of disproportioned collapse of framed structures. Design codes recently recognized it by adding a new requirement: the structural robustness. Among the different approaches to check robustness, the most popular is associated with the column loss scenario: the analysis should verify that, in case of a column loss, an alternative load path does exist, limiting the portion of structure affected by collapse. Consequently, numerous experimental and numerical studies of 2D and 3D structures were carried out in recent years to identify the mechanism of load transfer from the damaged to the undamaged part of the structure. This knowledge becomes an essential and fundamental key for assuring adequate resistance against progressive collapse by the development of catenary action in the beams and membrane action in the floor slab. Studies of reinforced concrete systems and of bare steel sub-assemblies are numerous. More recent is the focus on the response of steel–concrete composite structures subjected to accidental events. Furthermore, most of these studies focused on the characterization of 2D sub-assemblies or 3D in-scale framed structures. This paper presents an experimental assessment of the structural response of a 3D full-scale steel and concrete composite frame under the column loss scenario. The results are finally compared with the response of a frame with the same overall geometry but different columns’ layout, tested by the Authors within the same research programme.

Damage identification of structures based on sensitivity equations using PCA and PSD data

This article presents a novel model updating approach to the problem of structural damage identification. The approach is based on principal component analysis (PCA) of power spectral density (PSD) data obtained from incompletely measured structural responses. Damage detection was done by solving an innovative sensitivity equation based on least-squares optimization that could help solve the problem in a time-efficient manner and extend the results for industrial applications. Simulations of a 2D steel truss and a 2D steel frame were considered for a thorough comparison. The simulation results clearly showed the effectiveness of the method and its superior performance for solutions such as a PSD-only strategy and frequency response function (FRF) based data analysis along with singular value decomposition.

Reliability-based layout optimization of concentrically braced in 3D steel frames

For an economical and safe design of building systems with concentrically braced frames, the layout of the braces should be done by considering all limitations. The current study proposes an approach for a reliability-based optimal design of concentric bracing layouts in 3D steel frames. The objective function was considered to be a reduction in the total weight. The layout of the braces was considered as the variable of the optimization problem. The deterministic design constraints of limitations of strength, drift and torsional irregularities were considered according to AISC 360-16 and ASCE 7-16. The distance between the center of mass and the center of rigidity was defined as the probability constraint. The probabilistic variables were the intensity of the distributed loads and the cross-sectional area of the braces and columns. The reliability index was evaluated using the Monte Carlo simulation method. The reliability-based design optimization (RBDO) problem was solved for 4-, 5- and 9-story steel space frames using the EVPS algorithm. To investigate the effect of the probabilistic constraint on the optimal design, numerical examples were solved without applying this constraint and the solutions to the RBDO and deterministic design optimization problems were compared.

Affordable Earthquake Building

Abstract: Nowadays springs are the main component in the structures. A new low-cost seismic isolation system which is related on spring tube bracings has been proposed and studied, and according to that study when springs are performed their designated jobs there is very little reason to spare them much thought. One area that you might not have considered the worth of springs within is the science of architecture, but actually springs are being used in buildings all around the world. As per the study, multiple compression-type springs are positioned in a special cylindrical tube to obtain a symmetrical response in tension and compression-type axial loading. An isolation floor, which consists of pin-ended steel columns and spring tube bracings, is constructed at the foundation level or any intermediate level of the building. An experimental campaign with three stages was completed to evaluate the capability of the system. First, the behavior of the spring tubes subjected to axial displacement reversals with varying frequencies was determined. In the second phase, the isolation floor was assessed in the quasi-static tests. Finally, a ¼ scaled 3D steel frame was tested on the shake table using actual acceleration records. The transmitted acceleration to the floor levels is greatly diminished because of the isolation story, which effects longer period and higher damping. There are no stability and self-centering problems in the isolation floor.

Investigation of changes in steel frames stress state in fire and influence on its vitality

Modern studies of the multi-storey buildings load-bearing structures vitality are analyzed. The shortcomings of the previously studied measures to increase the steel multi-storey frames vitality are identified. The need to study more effective and cost-effective measures have been identified. The change of 2d steel frame various elements loading during a fire is investigated. The dependence of the frame load-bearing capacity on the location of the fire source on different floors and spans is analyzed. 4 scenarios of fire source location in 2d multi-storey frame are considered. The influence of the distribution of the internal forces in the heated beams on the frame stress state, in particular on the local buckling of the I-beam flange and the web is analyzed. It was found that due to temperature expansions due to fire, not only heated elements are can be the first to be damaged in the frame. It is established that during a fire the first destruction occurs faster in the outside span of the frame than in the middle. When comparing the fire scenarios on the lower and upper frame floors, it was determined that on the lower floor the columns are more prone to damage earlier than the beam on the upper floor. When comparing the fire scenarios in the middle and outside frame spans, it was determined that in the middle span the beams are more prone to collapse earlier than the column than in the outside. It has been confirmed that, depending on the fire source location on different floors and spans, both the beam and the column of the frame may be the first to collapse. It is established that depending on the fire source location there may be different mechanisms of multi-storey frame collapse. It is established that the frame structures' stress state is significantly influenced by the distribution of internal forces at temperature loads, and not only fire protection and steel structures fire resistance.

Behaviour of thin flush end-plate connections in a 3D bare steel frame under fire loading: experimental study

PurposeThe paper aims to report a fire test conducted on a three-dimensional frame in order to investigate the behaviour of bare steel flush end-plate connections with relatively low thickness at elevated temperatures.Design/methodology/approachA half-scale model was fabricated and exposed to modified (scaled) ISO 834 heating curve using a semi-open furnace. The maximum temperature inside the furnace reached 1,026 °C.FindingsThe rotations of connections are reported and compared with those of a previous study on an exactly the same model with thick end-plates. Various modes of failure such as local buckling of the beams flanges and lateral-torsional buckling of beams were observed during the test. Finally, the structure collapsed after 29 min of heating due to the fracture of weld between one of the beams and one of its attached end-plates whilst the other beam had undergone a maximum deflection of 35 cm (≈ 1/6 span length). Other observed failure modes included bolt fracture, bolt thread stripping and large inelastic deformation of the end-plates.Originality/valueAlthough the adoption of thin end-plates increased the rotational capacity of the connections, it did not improve the robustness of the structure under fire conditions.

Effect of member grouping and pool size of discrete cross-sections on the optimal design of a large-scale 3D steel frame

This paper examines the effect of member grouping and selected pool size of discrete cross-sections on the optimal design of a large-scale steel frame structure. Member grouping is commonly applied to structural optimization problems to significantly reduce the solution space of candidate designs and improve the efficiency and robustness of the search to achieve near-optimum solutions. At the same time, discrete sets of cross-sectional steel shapes (profile lists) assigned to a particular member group are often limited to a subset of cross-sections to further limit the search space and ensure practicality in the final design. However, for large-scale structural systems (e.g., tall buildings), limiting the number of member groups coupled with the exclusion of lighter cross-sectional shapes may significantly impact the quality of the optimal solution (i.e., weight of the frame). This work presents a case study of a large-scale three-dimensional (3D) steel frame to evaluate the sensitivity of the optimal design to practical combinations of member groups and steel profile lists used in multi-story steel frames. A recently developed metaheuristic search algorithm was applied to the steel frame and independent optimization experiments were performed for 16 unique member grouping and profile list combinations (cases) to quantify their influence on the variability and quality of the optimal design. Results reveal a 33% difference in the optimal (final) weight between member group and profile list combinations producing the smallest and largest solution spaces. Yet, the lightest design (corresponding to the largest solution space) produced a greater number of unique steel shapes and required significantly higher computational cost.

Experimental and Numerical Study on the Robustness of Full-Scale Volumetric Steel Module under Sudden Support Removal Scenarios

AbstractThis paper presents and discusses the experimental and numerical results performed on a 3D modular steel frame under sudden corner support removal scenarios. A modular steel frame was desig...

Effect of Friction Dampers on Seismic Response of Steel Frames

Abstract This paper deals with effect of friction dampers on seismic response of 2D steel frames in comparison with structures stiffened by large sections and centrally braced. For the present study three structures with six storeys are subjected to a time history analysis. To study the effect of dampers in structures in comparison with structures stiffened by large sections and centrally braced, are analysed the relative level displacements, maximum displacement on the top, variation of lateral acceleration at the last level and variation of the maximum seismic base shear force depending on the lateral rigidity. The results indicate that placement of friction dampers improve the response of structures in all analyzed terms.

Multi-objective design optimisation of steel framed structures using three different methods

PurposeThe optimality objectives are the structure weight and embodied energy as well as calculating the cost and embodied carbon of the resulting optimum options. Three optimality algorithms developed in MATLAB, namely, genetic algorithms (GA), particle swarm optimisation (PSO) and harmony search algorithm (HSA), were used for structural optimisation to compare the effectiveness of the algorithms. Two life-cycle stages were considered, production and construction stages, which include three boundaries: materials, transportation and erection. In the formulation of the optimum design problem, 107 universal steel beams (UKB) and 64 columns (UKC) sections were considered for the discrete design variables. The imposed behavioural constraints in the optimum design process were set according to the provision of Eurocode 3 (EC3). The study aims to find the optimum solution of 2D steel frames whilst considering weight and embodied energy, investigate the performance of the analysis integrated with MATLAB and provide three examples to which all these are applied to.Design/methodology/approachUndoubtedly, in structural engineering, the best design of any structure aims at the most economical and environmental option, without impairing the functional and its structural integrity. In the paper, multi-objective stochastic search methods are proposed for optimum design of three two-dimensional multi-story frames.FindingsResults showed that the optimised designs obtained by HSA are better than those found by the GA and PSO with an average difference of 16% from GA and PSO, where this difference increases at larger frame structures. It was, therefore, concluded that the integration of the analysis, design and optimisation methods employed in MATLAB can be effective in obtaining prompt optimum results during the decision-making stage.Research limitations/implicationsThere may be some possible limitations in the study. Due to the time constraints, only three meta-heuristic approaches were investigated, where more methods should be investigated to fully understand their effectiveness in multi-objective problems.Originality/valueInvestigating the performance of three optimisation methods in multi-objective problems developed in MATLAB. More importantly, developing optimisation models for evaluation of embodied energy, embodied carbon and cost for steel structures to assist designers, during the initial stages, to evaluate design decisions against their energy consumption and carbon impacts.

Improved Substitute-Frame (ISF) model for seismic response of steel-MRF with vertical irregularities

This paper attempts to evaluate and improve the Substitute Frame (SF) model recently proposed by the authors to be used in simplifying moment resisting frames with various vertical irregularities besides the non-fulfilled Strong-Column/Weak-Beam (SCWB) concept. Accordingly, two improvements related to the setback irregularities and SCWB issues have been proposed. For those cases where the current SF model makes inadequate estimations of the original frame, the proposed improvements make it possible to overcome the existing problems and get more accurate results. For this purpose, a combination of 24 full-frame 2D steel frames has been designed and modeled in OpenSEES software. Then, the analysis results were compared to those of the corresponding SF models in terms of modal, nonlinear static, and dynamic analyses. In this regard, three sets of ground motions were selected by the Conditional Spectrum method including weak far-fault, strong far-fault, and severe near-fault ground motion records. To gain further insight and achieve reliable outputs, more than 4000 runs of dynamic time history analyses have been carried out. The results show that the SF model can predict periods and modal shapes of the original frame with excellent accuracy. For performing nonlinear analyses, by applying the proposed improvements for the required cases, the Improved Substitute Frame (ISF) model can estimate the global behavior and maximum interstory drifts of the original frame with high accuracy.

Assessment of existing steel frames: Numerical study, pseudo-dynamic testing and influence of masonry infills

Most of existing steel multi-storey frames in Europe have been designed before the introduction of modern seismic design provisions, hence they often exhibit low performance under earthquake loads due to their low lateral resistance and energy dissipation capacity. In addition, such structures often include rigid and brittle masonry infill walls that highly influence their lateral response and distribution of damage pattern. However, current procedures for the assessment of existing steel buildings in Europe, included in the Eurocode 8 – Part 3 (EC8–3), do not provide adequate guidance for the assessment of ‘weak’ steel frame with masonry infill walls. Moreover, most of available modelling approaches of masonry infills formerly developed for reinforced concrete (RC) structures do not properly represent the behaviour of infill walls in steel frames. An improved numerical has to be provided to satisfactorily mimic infill walls' behaviour in steel moment frames. To this end, an experimental and theoretical study was carried out within the framework of HITFRAMES (i.e., HybrId Testing of an Existing Steel Frame with Infills under Multiple EarthquakeS) SERA project. This paper firstly presents the limitations of current EC8–3 by conducting a code-based assessment on a case study steel moment frame using pushover analysis. Three different single strut models, widely used for simulating the presence of masonry infills in RC structures, are considered for the numerical analyses. The paper also presents the results of pseudo-dynamic (PsD) tests performed on a large-scale 3D steel frame with masonry infills. The capability of the different masonry infill models is successively evaluated by comparisons between numerical and experimental results. On the basis of the obtained results, recommendations on how to potentially improve the single strut model for masonry infills surrounded by steel frames are also provided.

Impacts of residual stress and shear deformation on 2D steel frames using fiber plastic hinge element: nonlinear behavior and strength

In this study, impacts of residual stress and shear deformation are investigated on 2D steel frames using a new fiber plastic hinge method. Geometry and material nonlinearities, residual stress, shear deformation, imperfections are considered simultaneously in the nonlinear analysis. The proposed method is efficient in computational efforts since the one-element modeling is used for the nonlinear analysis by employing stability functions for capturing the P-small delta phenomenon. The P-large delta phenomenon is considered using the geometric stiffness matrix. Plastic hinges are assumed to be formed at two ends of members. Cross-sections at two ends of members are divided into many fibers. The ECCS residual stress pattern is assigned directly through fibers as initial stress conditions. A finite element program is coded using the Fortran programming language for predicting the nonlinear behavior and ultimate strength of planar steel frames. The behavior and load-carrying capacity of steel frames are predicted precisely and efficiently using the nonlinear inelastic analysis. A case study of a large-scale planar steel frame is investigated for the frame's behavior and strength under the effects of residual stresses and shear deformation. Through numerical examples, we recommend that both residual stress and shear deformation should be considered in the advanced direct analysis and design procedures for steel-framed structures.Article highlightsA nonlinear 2D beam column element is developed successfully using onlyone element per member for modeling.Geometric nonlinearities, material plasticity, residual stress, and sheardeformation are investigated simultaneously.Both residual stress and shear deformation should be considered in the engineering design of steel frames.

Seismic Performance of Steel Framed Building With Mass Irregularities With The Use of Different Combinations of Base Isolators and Dampers

This study addresses the nonlinear seismic responses of 3D Steel frame building upgraded with a series of passive protective systems. To this, friction damper (FD) as an energy dissipation device and lead rubber bearing (LRB), and friction pendulum bearing (FPB) base isolators are considering. For this purpose, eight different cases are taken into account. The first case contains a ten-story steel frame regular compare with irregular buildings (mass irregularities) as fixed-base (FB), the other four cases are the single use of FD, LRB and FPB in such frame, and the last three cases are the combined use of FD with LRB and FPB, Combination of isolators LRB and FPB, Combination of LRB, FPB and FD. Above same cases are considering for fifteen story steel frame regular buildings compare with irregular buildings (mass irregularities). Two ground motion records considering in this study by non-linear time history analysis in ETABS.

Collapse performances of steel frames against fire considering effect of infill walls

This study numerically investigates effect of infill walls on collapse performances of three-dimensional (3D) steel frames against fire using explicit nonlinear dynamic analysis. Two eight-story, five-span with three-bay composite steel frames were designed, one of which has no infill walls (bare frame) while the other one has infill walls (infilled frame). The fire resistance, load redistribution mechanisms of the structures subjected to single compartment fire are investigated. Frame analysis against traveling fires is also conducted. Moreover, the effect of parameters including load ratio, opening percentage and number of infill walls are also studied. Results indicate that the damaged compartment moves down in fire and drags the other part of the frame, causing overturning deformation in the frame in the short span and the twist of the entire structure. The infill walls decrease the buckling temperature of the heated columns, whereas significantly increase the collapse temperature of the steel frames. The strut action of infill walls drastically changes internal forces within adjacent columns, significantly altering load redistribution path of steel frames against fire. The collapse modes of the steel frames can be greatly altered by the presences of infill walls. The steel frames collapse at a lower temperature with increasing load ratio and opening percentage of infill walls, whereas collapse at a higher temperature with more infill walls. Finally, a preliminary analytical approach is proposed to predict collapse modes of steel frames against traveling fire.