Steel Profiles Research Articles

Push‐out tests on steel sections encased in steel fibre reinforced concrete

AbstractThe configuration object of this study is a steel H‐shaped profile encased in reinforced concrete where the shear connection is obtained by rebars passing through holes in the web of the steel profile. This configuration is common for different structural typologies such as filler beam decks, slim‐floor beams, H‐pile head, or beam‐end anchorages. Experimental push‐out tests were performed at the University of Luxembourg with the objective to investigate the impact of using steel fibre reinforced concrete as an addition to the traditional bar reinforcement. The geometrical configuration was representative of the intended final application as filler beam deck and three specimens were casted with normal concrete and three specimens with steel fibre concrete. The main contributors of the shear connection resistance are surface friction at lower load levels and the reinforced concrete dowels through the web holes for higher load levels. Though a robust rebar reinforcement was foreseen, results showed a considerable enhancement of the structural performance thanks to the presence of steel fibres even for a moderate volumetric ratio. The enhanced tensile properties highly contribute to the shear resistance of the concrete matrix, ensuring higher resistance levels before the activation of shear failure surfaces. Steel fibres also confer a higher ductility to the concrete matrix particularly useful at steel‐concrete contact interfaces where high local pressures take place.

Parametric Analysis of Steel Studs to Reduce Thermal Bridges in Light Steel Framing Construction Systems

Thermal bridges significantly affect the thermal performance of light steel framing systems due to the high thermal conductivity of steel. The objective of this study is to identify modifications on the steel profiles to reduce heat flux and improve the thermal resistance of both single- and double-layer wall panels. Three approaches were analyzed: (i) slotted steel studs, (ii) integration of less-conductive materials into the web section, and (iii) modifications to web geometry. A numerical model was calibrated based on experimental data and used to perform dynamic simulations with different configurations. Results show that incorporating less-conductive materials, such as rigid polyamide, achieved a heat flux reduction of up to 98%, while optimized slotted patterns reduced heat flux by up to 90%. The results also demonstrated that all web modifications effectively reduced heat flux through the wall, with approaches (i) and (ii) showing the greatest impact. The shape of the slots also has an important impact on the heat flux. The most effective strategy for enhancing the thermal performance of the steel studs was the use of a less-conductive material.

Fire performance of wood–steel hybrid elements: finite element analysis and experimental validation

Wood-steel hybrid (WSH) elements are gaining popularity in the construction industry due to their reduced environmental impact and high load capacity. However, fire resistance remains a crucial challenge for advancing wood as a construction material. The proposed WSH slab consists of a trapezoidal steel profile sandwiched between two laminated veneer lumber (LVL) beech panels. This research aims to numerically predict the fire performance of the proposed WSH slab element by generating heat transfer models that consider convection, radiation, and conduction. The objectives are to predict the temperature profile of the system's components, assess the charring rate of the LVL panels, and validate the results with experimental fire tests. Computed Tomography (CT) scanning was additionally used to detect the material density variation in the remaining LVL layers after fire tests. Simulations reveal that the size and shape of the internal cavity significantly influence heat flow within the system. Analysis of different thicknesses and heights of the steel sheet shows a substantial impact on the charring initiation time of the upper LVL layer. Temperature profiles of the components from numerical analysis exhibit similar behavior to that observed in the experiments. The experimental charring rate averages between 0.88—1.00 mm/min, while the numerical rate averages between 0.95—1.06 mm/min, with a 5–8% average deviation attributed to conduction interaction between LVL and the steel sheet. This variation may also be caused by the definition of generic thermal properties of wood according to EN1995-1-2, which may not accurately represent the behavior of the LVL element under fire.

The use of normative models under combined compression and bending for verification of concrete-filled steel tubes with high strength materials

Buildings have been demanding increasingly slender pillars from projects, consequently increasing the demand for efficient and economical solutions. One of the solutions adopted is the use of high-strength concrete and steel and the optimization of sections for filled mixed tubular pillars, which has been widespread in European, American, and Asian countries; however, there is little application in Brazil's constructions. Verification of mixed pillars under flexo-compression can be done by simplified methods or analytical methods such as the method of deformation compatibility. The draft revision of ABNT NBR 8800:2023 introduces three simplified calculation models for flexo-compression verification, with limitations in its application for concrete with characteristic compression strength below 50 MPa and steel profile with yield strength below 450 MPa, as well as proposing polygonal lines to trace interaction curves. In this article, the simplified calculation models from the draft revision of ABNT NBR 8800:2023 are compared with experimental results from the literature of prototypes of circular tubular filled mixed pillar sections with concrete strength above 50 MPa and steel profile with yield strength above 450 MPa. For this purpose, a computational tool was developed in MATLAB that traces the interaction curves of the draft revision project of ABNT NBR 8800:2023. The suitability and conservatism of simplified methods were verified when using high-strength materials outside the normative range.

Nonlinear finite element analysis of steel-concrete composite beams with cellular I-section under hogging moment

Adopting hybrid cellular I-sections can favor optimizing steel consumption, as the higher steel grade is localized only in the compression tee. In addition, continuous steel-concrete composite cellular beams allow the construction of longer spans due to the combination of higher bending stiffness of the cellular I-section and its connection with the concrete slab, further the continuous of the beam, which provides a better distribution of the bending moment diagram. However, due to the hogging moment on the support regions, the steel-concrete composite beam can present lateral instability of the compression flange accompanied by web distortion, named Lateral-DistortionalBuckling (LDB). No investigations have evaluated the behavior of steel-concrete composite beams with hybrid cellular I-section under hogging moment. This way, the present study aims to assess the behavior of the structure in question using a nonlinear finite element model via ABAQUS software. The investigation consists of verifying the beams' failure mode, considering plastic behavior or LDB, and the effectsof different combinations of steel grades for the hybrid I-section, and further comparing the use of hybrid and homogeneous steel profiles on the composite beams.

Retrofit and assessment strategies on heritage buildings: a case study of bank archive building in semarang old town area

Abstract Retrofitting in cultural heritage buildings to be revitalised has quite complex challenges, in addition to problems Efforts to maintain the performance of technical strength and repair limits on building elements are not flexible such as new buildings. This research aims to evaluate the method of implementing the revitalization of cultural heritage buildings through structural assessment. The case study method used on the Bank Archives Building object elaborated analysis to determine the safest Retrofit strategy. The analytical method used in this study is quantitative method using primary data obtained from direct observation and secondary data obtained from previous research case studies. The results showed that in planning a retrofit at the Bank Archives Building there were several technical and non-technical obstacles. Thus, the assessment method chosen includes several methods, including visual detail inspection, four non-destructive tests, one destructive test, and one soil test. These data are used to perform structural and geotechnical analysis. The results of structural analysis show that the quality of concrete in the structure of the Bank Archive Building does not meet the technical requirements of the building while the results of geotechnical analysis show that the decline in the structure of the Bank Archive Building has relatively little potential. The retrofit strategy that can be applied is a bending moment frame from a steel profile. This aims to increase the load capacity evenly distributed on the structure of the Bank Archives Building.

Experimental analysis of the performance of screwed connections for steel-timber composite beams

The proposed research addresses the structural behavior of screwed connections in composite beams consisting of Cold-Formed Steel (CFS) profiles and timber boards. An experimental program consisting of 30 push-out tests involving six different models was conducted to evaluate the performance of different types of connection. The screw diameter and spacing were different in each model, and in one out of every five specimens of each model, the screws were installed with steel washers. Results indicate that the screws’ diameter influences the connection’s load-carrying capacity. Results also indicate that the spacing of screws influences the connection’s longitudinal shear flow: the larger the spacing between screws, the lower the longitudinal shear flow. Conversely, results from connections involving steel washers did not show any increase in load-carrying capacity or stiffness. The failure mode detected in the tested specimens resulted from the crushing of the Oriented Stranded Board (OSB) related to the rotation of the self-tapping screws. The typical failure mode, called "screw tilting", can be explained by analyzing the axial and transverse projections of the push-out force, where the latter causes crushing of the timber through contact pressure, and the former induces tension in the screw.

Experimental Analysis of CSC-type Shear Connectors Behavior under Direct Shear: Pry-Out Test (I)

The use of steel and concrete composite sections has been recorded since the early 1950s, mainly in Europe and North America, as pioneers in the industrial production of steel elements. These systems have become popular in the world due to the efficiency of structural behavior, where steel withstands tension and concrete develops its bearing capacity in compression, being essential for the installation of stress transfer elements at the interface, called shear connectors. Recently, the use of cold-formed steel sections (CFS) has been included as a cost-effective alternative in the construction of small and medium-sized buildings. In this way, it complements concrete elements, allowing the formation of highly efficient systems, mainly in flooring systems. In this research the experimental validation of the behavior of CSC-type shear connectors is proposed, configured by Hurtado & Molina (2020), which are applicable to these CFS-concrete configurations. Pry-out tests were carried out, initially proposed by Anderson & Meinheit (2005), where the axial tensile load is applied to the steel section. This alternative experimental proposal differs from traditional push-out tests, since compressive loads can generate local bucking in steel shapes, particularly in CFS sections. The experimental results were statistically analyzed, evaluating the incidence of the compressive strength of the concrete, the thickness of the steel profile, and the spacing between connectors on the bearing capacity of the composite system. As a result of the research, the design formulation for CSC-type shear connectors in CFS-concrete composite sections is proposed. Keywords: composite sections, CSC-type shear connector, cold-formed steel (CFS), design formulation

Reliability Analysis for Dynamic Behaviour, Stiffness, and Strength of Existing Steel Truss Bridge BH77

Railway bridges are old, especially on the Sumatra island and according to earthquake map on 2017 version show an increased risk, it is necessary to analyze the reliability of dynamic behaviour to extend the bridge life and damage can be detected early. The bridge reliability was assessed in terms of natural frequency, deflection, and internal force . The study was conducted on the BH77 Railway Bridge in Tegineneng-Lampung, a through truss type. Reliability analysis with a non-deterministic approach, using the probability concept, variability used is the dimensions of steel profiles based on fabrication drawings and field measurements. The research uses secondary data, one of which is measurement of the circumference of the steel cross section, that influenced by the paint layer, where the paint thickness sample to correct and obtain the actual dimensions. Dynamic behaviour analysis, consisting of modal analysis, Fast Fourier Transform, time history, and First Order Reliabilty Method. The analysis results showed the effect of steel dimension correction compared to the fabrication drawings did not have a significant effect on the changes in the values of natural frequencies, mode shapes, deflections, and internal forces. The reliability of the dynamic behaviour obtained was 99% at all reviews. Which indicates that the bridge is safe against potential resonance, the bridge stiffness is still high, and the axial+moment capacity is still sufficient against static & earthquake loads, as well as good bridge maintenance. The largest deflection point as a reference for placing strain and vibration gauges on structural health monitoring systems.

Developing lightweight steel profile and lattice polymeric core composite for structural use

Embracing modular construction, advanced materials, and digital technologies can drive innovation in the building industry, address global material consumption challenges, and foster a sustainable future. This paper presents the innovative concept of the lightweight hybrid lattice-filled profile (HLFP) for modular engineering, which combines a thin-walled steel tubular shell and additively manufactured lattice structure (AMLS) as a lightweight core. The AMLS achieves precise shape, internal structure, and stiffness, ensuring the decided structural performance with minimum materials. This study provides a theoretical model of HLFP, focusing on adhesively bonded AMLS. The experimental verification demonstrates that the adhesively bonded AMLS ensures an additional 130 % during the elastic stage and, even after partial debonding, maintains 50 % of the mechanical resistance compared to the theoretical sum of the HLFP components. Reducing the infill density does not severely affect the load-bearing capacity of the HLFP—a fourfold decrease of the ALMS density (from 10 % to 2.5 %) results in a 20 % decrease in the ultimate load. However, the sparse lattice structure alters the failure mechanism of ALMS, changing it from favorable ductile to dangerous brittle and determining the object for further optimization. The parametric study reveals the efficiency of the theoretical model for predicting the load-bearing capacity of HLFP. However, the finite element model developed in this study should be used for a more detailed analysis of the HLFP's structural behavior.

Introduction to the Investigation of reproduction of the real geometry of UBM panels

The article concisely describes UBM technology (Ultimate Building Machine), that can be used as a solution for buildings and roof structures. The structure of this technology is made of double corrugated thin-walled steel profiles manufactured on the construction site by a self-contained UBM manufacturing factory on wheels. These panels serve as both the building envelope and the structural system. The specificity of the construction poses many design problems, especially the determination of the strength parameters and stiffness of the double-corrugated panels from which the structure is made. The article presents the results of spatial scanning tests of double-corrugated steel sheets, which were carried out using commonly available 3D scanning devices: Leica 3D Disto and MagiScan app. Additionally, results of numerical analyses performed on scanned samples and a comparison of these results with preliminary laboratory tests have been presented in the article. The purpose of scanning was to obtain an accurate and real geometry of the UBM panels, to implement it into a numerical software, and then to perform numerical analyses. Commonly available 3D scanning devices were used because using advanced 3D scanners is not popular nowadays for economic reasons, and hand-built geometric models pose a lot of problems and are not accurate enough. Promising results were obtained, which form the basis for further research.

Development of a Quality Control System Using Modal Analysis to Evaluate a Multi-Point Projection Welding Process.

The article presents the results of the development and research regarding the application of modal analysis to the evaluation of a multi-point projection welding process. The quality control system is based on the information provided by modal analysis for the entire welding station after the previously completed welding process. The research is carried out due to the lack of an effective method for assessing the course of the multi-spot projection welding process in the case of a single current circuit passing through many points at the same time. A study of the applicability of modal analysis in investigating the quality of a multipoint joint was conducted for four DIN 928 nuts welded to a steel profile. The aim of the study was to determine the influence of weld defects on the displacement of resonant frequencies. To realize the objective, the dynamic properties of the entire welding station, including the sample in the frequency domain, were investigated. In the first stage of the study, a finite element method was used to perform modal analysis and examine the form of vibrations for the individual natural frequencies of the welding fixture including the sample. Then, quality verification using the dynamic resistance method was performed, which was compared later with the modal approach. The last stage of the study was to conduct modal analysis in the frequency domain to verify the numerical studies.

Design model for shear keys used as thermal break systems in balcony-slab joints under combined shear and bending loads

Balcony-slab joints (BSs) are common in residential buildings. Integrating thermal break systems (TBSs) can reduce the energy loss resulting from thermal bridging. However, the mechanical performance of BSs equipped with TBSs against shear and bending remains hardly explored in design and experimentation. The aim of this study is to evaluate the mechanical behavior of BS joints under combined shear and bending actions, taking into account the presence of TBSs. Seven large-scale balcony-slab specimens were fabricated and tested under vertical loading with different moment-shear ratios (M/V). The BSs are equipped with TBSs comprising steel bars and shear profiles. A simplified finite element (FE) model was then developed using the ABAQUS software. The FE model employs spring-like elements to simulate the bond and contact behavior between concrete and steel, reproducing both the resistance and stiffness of the tested specimens. On the basis of the experimental and FE results, a resistance model consistent with the Eurocode design guidelines was drawn. Finally, moment-shear (M-V) interaction curves for balcony-slab joints were generated at the ultimate (ULS) and serviceability (SLS) levels, considering the impact of horizontal loading to achieve comprehensive design insights. The tests and FE results showed that the moment-shear ratio (M/V) significantly influences the shear capacity of the BS joints. The steel profiles effectively acted as shear keys connecting the balcony and the slab. A strength reduction coefficient of 0.701 was introduced for the design.

The effect of cold forming residual stresses in local fatigue approaches: A numerical perspective

Thin-walled structures generally rely on cold-formed mild steel profiles. Due to cold forming, a significant formation of residual stresses impacts their overall fatigue behaviour. In this work, a state-of-the-art framework for fatigue life prediction is proposed and applied to both roll-formed and press-braked full-scale profiles. In summary, the profile’s manufacturing process is numerically simulated to obtain a representative residual stress field. These results are then used as the initial state during a subsequent structural and fatigue analysis. A clear detrimental residual stress effect is verified. Importantly, however, is to note that prediction accuracy increases significantly when these effects are considered.

Experimental and Numerical Study of Steel-Concrete Composite Beams Strengthened under Load.

This study analysed the strengthening process of a classical steel-concrete composite beam. The beam consisted of a reinforced concrete slab connected by shear studs to an IPE steel profile. The key idea was that the composite beam was strengthened under load. This process simulated an actual reinforced structure that is always subjected to dead loads, with possible service loads. This study assumed that strengthening was implemented to increase the load-carrying capacity and stiffness, not as a way for simulation a repair. The strengthening consisted of expanding the steel part of the beam by welding an additional plate to the bottom flange of the IPE profile. This study included the results of numerical analyses conducted in Abaqus software and lab results. A three-dimensional numerical model was created, taking into account the non-linear behaviour of concrete and steel, the susceptibility of the composite at the joint plane, and the residual stresses created during welding. A full-scale strengthening of the composite beams under load was carried out. Comparison of the results obtained in the experimental tests and numerical analyses showed a very high convergence of the results, as well as in terms of the non-linear operation of steel and concrete. This confirmed the validity of the created numerical model, which can be the basis for further research into the process of optimal strengthening of composite elements.

Effect of compound surface modification of shot peening and DLC coating on surface integrity and fatigue properties of gear steel 16Cr3NiWMoVNbE

We conducted a study on the surface compound modification of shot peening and pure carbon DLC coating to simultaneously meet the requirements of wear resistance and fatigue resistance of spline structure. The effects of surface compound modification were investigated on the surface morphology, residual stress profile, microstructure, and nano-indentation hardness of 16Cr3NiWMovNbE gear steel, and conducted a comparative study on fatigue performance. The results show that the surface compound modification inherits the surface morphology and compressive residual stress gradient of shot peening, while the surface residual stress is slightly smaller than that of shot peening. In addition, surface compound modification still reflects the characteristics of high hardness and high fracture resistance of DLC coatings. Under the bending load based on spline tooth root, compared to the original specimen, the fatigue life after shot peening, pure carbon DLC coating, and surface compound modification is increased by 3.68, 2.35, and 3.36 respectively. Although the compound modified surface still maintains the shot peening morphology with a increasing surface roughness and stress concentration coefficient, the 100 μm-depth compressive residual stress profile and the subgrain refinement layer introduced, as well as the hard surface layer with good load-bearing capacity, have played the role of fatigue strengthening.

Comparativo da utilização da NBR 8800 e da NBR 14762 para o dimensionamento à flexão de perfis de aço

Este artigo apresenta os resultados da resistência à flexão de perfis de aço laminados com formato U e perfis formados a frio de seção UDCS (U dobrado de chapa simples), utilizando os procedimentos das Normas Brasileiras ABNT NBR 8800:2008, que trata do projeto de estruturas de aço e de estruturas mistas de aço e concreto para edifícios, e ABNT NBR 14762:2010, que aborda o dimensionamento de estruturas de aço constituídas por perfis formados a frio. Para a análise, foram desenvolvidas rotinas no software Microsoft Excel, que possibilitaram a realização de comparações quanto à viabilidade de uso dos dois tipos de perfis. As comparações incluíram grupos de perfis dos dois tipos, selecionados com base em áreas de seção transversal semelhantes e momentos de inércia próximos, a fim de estabelecer parâmetros mais precisos para a análise. Os resultados indicaram que, apesar de ambos os perfis atenderem a requisitos específicos de resistência, os procedimentos normativos das duas normas ABNT aplicadas não são diretamente comparáveis entre si, o que implica na necessidade de considerações distintas para cada tipo de perfil ao avaliar a sua viabilidade estrutural. Essa diferença destaca a importância de uma análise criteriosa na escolha dos perfis a serem utilizados em projetos estruturais, considerando as especificidades e limitações de cada norma.

Historical evolution of structural optimization techniques for steel skeletal structures including industrial design applications

This study covers the review of algorithms developed for the optimum design of steel skeletal structures from the first article published in 1960 until to date. The paper initially describes the mathematical formulation of a simple truss structural design problem. The early optimum design algorithms that were based on mathematical programming techniques where the design variables are assumed to be continuous are reviewed. The optimum design of steel framed structures necessitates the selection of steel profiles from the standard list of discrete steel sections and requires the satisfaction of design code provisions. Both mathematical programming and optimality criteria techniques need more capability to produce solution to this type of optimum design problems. Soft computing techniques emerged recently provide solution directly without needing any approximation. These techniques are classified and reviewed and their use in obtaining the optimum solution of actual industrial steel design applications is given.

Flexural mechanical properties of H-shaped steel-bamboo scrimber composite beams

To improve the torsional buckling resistance and enhance the load-bearing capacity and ductility of H-shaped steel beams with carbon reduction materials, the concept of combining H-shaped steel with bamboo scrimber has been proposed, in which the bamboo scrimber, an eco-friendly, lightweight, and high-strength material, promises significant structural benefits. Five full-scale specimens were designed and tested, including one H-shaped steel, two bamboo scrimber beams, and two composite beams. Additionally, further simulation tests were conducted using the verified finite element model (FEM). The experimental results revealed a remarkable increase in the ultimate bearing capacity of the composite beams by 96.5 % compared to bamboo scrimber-only beams and 72.7 % compared to steel-only beams. Meanwhile, distinct from the brittle fracture characteristics of the bamboo scrimber beams, which include instantaneous crack propagation and interlaminar cracking, the composite beams exhibited localized vertical cracks within the beam's tensile zone, effectively avoiding the torsional buckling issue of the H-shaped steel beam. The results further demonstrated that increasing the cross-sectional size of the composite beams can significantly enhance their flexural stiffness (up to 669 %), and reduce the deflection at the ultimate flexural moment. When the area of the bamboo scrimber in the cross-section was reduced with an unchanged steel profile, the initial stiffness dropped to 79 % without incurring any structural instability. Furthermore, by integrating the experimental and simulation results, a fiber element model for this composite beam structure is proposed to predict the maximum flexural moment value in the ultimate state. A corresponding calculation program was developed, and it is found that the calculated predicted ultimate flexural moment values exhibited negligible deviation from both experimental and FEM results, with AV of 1.0001, AAE of 2.21 %, and COV of 3.28 %.

Characterization of different longitudinal shear transfer mechanisms for profiles embedded in concrete walls

Concrete walls or columns reinforced by one or multiple embedded steel profiles have gained popularity due to their improved strength, ductility and energy dissipation capacity. However, certain gaps in information are remaining in the available standards regarding the design of such non-conventional reinforced concrete systems. In particular, a proper characterization of the longitudinal shear transfer properties at the steel-concrete interface is required for a reliable design. Although sufficient information is available regarding mechanical connectors like shear studs, detailed information is required for any other types of mechanical connectors such as welded steel plates or for configuration without mechanical connectors. Moreover, even for cases with mechanical connectors, the orientation of the profile – and hence the distance to the face of the concrete – and the tying system can have a significant influence on the load transfer mechanisms. To this purpose, this article presents the outcomes of a set of push-out tests with the objective of comparing the force transfer mechanisms from the steel profile to the surrounding concrete wall for different types of interfaces. 13 tests specimens are investigated, with flexible (shear studs) and/or rigid (steel plates) shear connectors, considering different orientations of the profile and tying mechanisms, as well as a comparison with profiles without mechanical connectors. Based on the test results and subsequent analytical assessment, relevant conclusions are drawn regarding the longitudinal shear transfer at the steel-concrete interface. If necessary provisions are followed, welded steel plates prove to be an effective alternative to the shear stud connectors in terms of connector strength. The orientation of the embedded steel profile, consequent position of the mechanical connectors and their distance to the concrete face are observed to have a significant influence on the compression strut evolution, which therefore dictates the necessity (or not) of horizontal confinement or ties. Furthermore, combining the shear strength offered by different types of mechanical connectors and the steel-concrete bond offer a precise estimate of the longitudinal shear strength and therefore indicates towards the conservative nature of the design provisions suggested by the available standards.