Steel Profiles Research Articles

Experimental Research and FE Model of a Bolted Steel-CLT Composite Connection

Steel-timber composite structures have numerous advantages compared to steel only and timber only structures. One of the most important parts of a composite structure is the composite connection. Object of this research was a steel-CLT composite connection consisting of a steel profile, a cross-laminated timber (CLT) panel and a bolt with nut and washer. Aim of the research was to develop an efficient finite element (FE) model of a bolted steel-CLT composite connection and to validate it experimentally. The research process consisted of several steps: experimental testing of the considered connection using asymmetrical push-out test, numerical modelling and analysis of the connection using Finite Element Method (FEM), validation of the numerical model using experimental results, and parametric study of the proposed numerical model. For numerical analysis, an innovative method for timber modelling has been proposed. The comparison between the experimental and numerical research results demonstrated that the proposed numerical model was convenient for practical application in structure analyses. The parametric study showed that, in some cases, atypical failure modes of the connection occurred. Based on registered behavior, a recommendation is given to calculate the load capacity of the connection integrally, taking into account both the primary (Johansen’s) and the secondary (rope effect) part of the connection strength, instead partially, as proposed by EN standards.

Total Focusing (TFM) for the Ultrasonic Testing (UT) of drawn arc stud welding

This article describes the results obtained applying ultrasonic testing (UT) with phased arrays (PAUT) using full matrix capture (FMC) and total focusing method (TFM) for the inspection of drawn arc stud welding. Weld studs are usually directly applied on the top of a metal slab using a dedicated welding gun. This procedure involves heating the end tip of the stud using a strong electric arc created by a positive electric current. This welding procedure shall comply to various normative requirements, but on the other side there is not a clear reference to any applicable non-destructive method (NDT) to control the quality of the weld seam. Shear connectors are normally used in concrete/steel composite structures to allow the combined action of the concrete slab and the steel profile thereby increasing both the stiffness and strength of the structure. Flaws in this connection would result in severe bending and cracking of the entire structure. This article proposes an advanced UT method to inspect the weld between shear connections and metal slab using FMC. Data acquired with FMC are processed by TFM algorithms improving image resolution, signal to noise performances and allowing 3D data imaging. The combined use of PAUT searching units and signal processing with high resolution measurement shows a great potential in industrial NDT applied to civil engineering, resulting in a more effective, reliable, and faster inspection methodology than many other methods, such as radiographic testing (RT).

A unified approach for fatigue detail categorization applied to rack structures

Rack structures made of thin-walled cold-formed mild steel profiles integrate automated storage-and-retrieval (S&R) systems operating on a 24/7 basis to satisfy the current demands of warehouse logistics. The cyclic storage of palletized goods combined with dynamic actions from S&R systems results in fatigue phenomena responsible for interruptions. However, cold-formed steel is missing from current European standards for fatigue design. Answering to the industry’s needs, the FASTCOLD project financed by the RFCS of the EU investigated the problem, generating important fatigue data. Additionally, several fatigue details are categorized via a unified approach based on a large data set regarding full- and small-scale fatigue tests.

Shear strength model for steel shape-reinforced concrete girders considering compatible steel–concrete interaction

Steel shape-reinforced concrete (SRC), also known as concrete-encased steel, offers numerous benefits compared with conventional reinforced concrete (RC) or bare steel due to its combination of RC and structural steel sections; therefore, SRC members find extensive use as transfer elements or girders in engineering applications. When evaluating SRC girders’ shear resistance, the direct strength superposition of RC and structural steel is basically used in most design codes, ignoring the steel–concrete interaction under shear, which has proven unreasonable because of the brittle shear behavior of RC. This paper suggests a novel method for assessing SRC girders’ shear resistance mechanism. The proposed method involves modeling the RC portion by a hybrid truss-arch analogy; in addition, based on the strain compatibility condition, the steel profile’s contribution is determined by applying the yielding criterion. Finally, the rationality of the proposed model is validated through a comprehensive comparison with previously published models and a set of 45 experimental test data samples available in the existing literature, and the results show that the proposed model can reasonably predict the maximum load-carrying capacity of SRC girders and is superior to existing shear strength models and code-based equations.

Fire resistance of austenitic stainless steel beams with rectangular hollow sections

AbstractThis paper presents a study on the structural behaviour of stainless steel profiles under fire conditions. An experimental campaign of three‐point bending tests on rectangular hollow section beams of the grade 1.4301 (also known as 304) were conducted, considering both steady‐state and transient state conditions. Prior to those tests, the mechanical characterization of the stainless steel was investigated. The constitutive laws obtained by tensile tests at high temperatures are compared with those recommended in Eurocode 3, whose respective material models were recently proposed for modifications, still requiring complete validation. In addition, numerical modelling of the bending tests has been performed afterwards achieving close approximation to the observed experimental results. Finally, analytical methods to predict the load‐deflection behaviour are also presented. Good agreement between the considered methodologies was attained validating their application on the prediction of the fire behaviour of stainless steel beams.

A mixed model reduction method based on the symmetrizer for two classes of dynamical systems

In regard of the cross Gramian and the block Arnoldi process, this paper focuses on mixed model reduction for two classes of dynamical systems. By studying the correlation between the cross Gramian and the Hankel singular values, model reduction via the cross Gramian is investigated for symmetric regular linear systems. Considering the non-symmetric regular linear system, associated with the symmetrizer, a convex optimization problem is established to obtain a symmetric system. Then, the non-symmetric regular linear system is divided into two parts, in which one is determined by the symmetric system and another is a non-symmetric counterpart. Model reduction via the cross Gramian is employed to reduce the first part. According to the structure of the non-symmetric counterpart, a modified version of the block Arnoldi process is developed to reduce the non-symmetric counterpart. The H2 error bound between the original system and the reduced system is discussed. This model reduction approach avoids partitioning the non-symmetric system into several single-input and single-output systems. Moreover, the proposed model reduction method can also be applied to the non-symmetric linear systems. Finally, the proposed model reduction approach is illustrated by a 2D convective thermal flow benchmark and an optimal cooling problem of steel profiles.

Experimental residual capacity of steel-reinforced concrete-filled steel tubular stub columns after fire exposure

Technological advances in the development of steel–concrete composite structures have led to the introduction of novel types of sections in the sought of higher load-bearing capacities. Particularly for composite columns, the axial capacity of concrete-filled steel tubular (CFST) sections may be enhanced by the introduction of an open steel profile embedded within the concrete infill, forming the so-called steel-reinforced concrete-filled steel tubular (SR-CFST) columns. An important aspect that should be revised, in order to safely use these sections in design, is their performance after a fire. In this experimental program, six SR-CFST stub columns are tested in the post-fire situation. Two series of columns comprising three circular and three square sections with the same steel usage are tested for comparison purposes. The size of the inner steel profile is varied in order to investigate its effect over the post-fire capacity of the columns. The specimens were initially exposed to elevated temperatures inside an electric furnace, and then cooled to ambient temperature; afterwards compressive axial load was applied gradually until failure, to ascertain their residual capacity. The experimental results show the high ductility of the SR-CFST stub columns after heating, with the circular specimens reaching higher post-fire peak loads than their square counterparts. This load increases with the size of the embedded steel profile. The post-fire capacities of the columns are evaluated through the Residual Strength Index, showing similar values for both circular and square SR-CFST columns. Finally, a design equation is proposed to facilitate the evaluation of the post-fire compression resistance of SR-CFST columns, as an extension of the existing room temperature design equation in Eurocode 4 Part 1–2 for CFST columns, accounting for the degradation of the steel and concrete after fire exposure through the corresponding residual factors.

Compressive behavior of FRP-confined cruciform steel-reinforced normal- and high-strength concrete columns

Fiber-reinforced polymer (FRP)-confined steel-reinforced concrete column (FCSRC), which consists of an external FRP tube and a steel-reinforced concrete (SRC) core, have been proposed to avoid the brittleness of SRCs. Capitalizing on the benefits of FRP-confine concrete, it is expected that full strength capacities of high-strength materials (i.e., high-strength concrete and high-strength steel) in FCSRCs can be exploited. Axial compression tests on FCSRCs with different strengths of concrete and steel were conducted in this study. A cruciform steel was adopted in FCSRCs. The parameters investigated in this study included the concrete strength, the steel strength and the FRP tube thickness. The test results demonstrated that the excellent performance of FCSRCs. Compared with normal-strength cross-shaped steel, the high-strength cruciform steel delays the development of hoop strains in the FRP tube for FCSRCs with normal-strength concrete. Additionally, the ultimate axial load of FCSRCs is generally larger than the direct summation of those of the steel section and FRP-confined concrete section (i.e., CFFT), demonstrating that the interaction between the three components (concrete, steel profile and FRP tube) in FCSRCs are in a benificial manner.

DESIGN OF A 10 TONS OVERHEAD CRANE WITH 21 METERS SPAN USING FINITE ELEMENT METHOD

A crane is a lifting equipment widely used to move cargo, construction sites, storage, and unload. The type of crane that is commonly used in industrial environments is the overhead crane. The overhead crane functions as a lifting device. Besides that, it also works as a load transfer tool even though the load being moved is limited to an environment that is not too large (indoor) at PT. A overhead crane is designed to overcome the problem of moving material in the mold storage area due to the area's expansion and the addition of 5-7 tons of mold material. Therefore, proper design is needed so the overhead crane can function properly. The design method uses the VDI 2221 or Finite Element with Solid works software. The results of the structure obtained are double box girder type girders with dimensions p = 21 m, t = 1224 mm, and l = 600 mm. The deflection results are 13.75 mm, and the runway uses steel profile I with dimensions 400 x 200 x 8 x 13 mm, with a deflection value at the runway stem of 5.6 mm. The type of wire rope used is type 6 x 37, with a diameter of 28 mm. The stress that occurs in the steel rope is 4306.1 Kg, less than the maximum allowable tensile stress of 8009.4 Kg. The single hook type with a hook diameter of 120 mm is made of material S45C. The tensile stress on the hook is 0.88 Kg, and the result is smaller than the allowable tensile stress of 12.72 Kg. The pulley diameter is 630 mm, the drum diameter is 604.9 mm, and the drum length is 279 mm.

Compatible Truss-Arch Model for Predicting the Shear Strength of Steel Shape-Reinforced Concrete (SRC) Beams

A steel shape-reinforced concrete (SRC) beam, in which a steel profile is encased in an R.C. section, is an essential configuration of steel-concrete composite members. Nevertheless, the precise estimation of shear strength for SRC elements is currently being explored due to the challenges associated with incorporating steel-concrete interaction. This paper establishes a compatible truss-arch model to simulate the shear behavior of SRC beams and predict their maximum shear strength. In the established model, the shear contribution of the R.C. encasement is evaluated using the traditional truss-arch model, and a stress decomposition based on von Mises yielding criterion and strain compatibility is conducted within the steel shape to decouple its shear contribution. Finally, the validity of the proposed model is confirmed using a comprehensive database. The comparison between the experimental and calculated results demonstrates that the established model can effectively and reliably calculate the SRC beams’ shear strength.

Behavior of embedded steel profile ultra-high performance concrete-filled stainless steel tubular short columns under axial compression

This study investigated the behavior of ultra-high performance concrete-filled stainless steel tubular columns with embedded steel profiles (ESUHPCFSST) under axial compression. Six short columns were designed with the parameters of diameter-to-thickness ratio and embedded steel profile ratio. Axial compression tests were conducted to investigate the failure modes, failure mechanisms, and the impact of relevant parameters on the mechanical properties of the specimens. A finite element model was developed and validated against the experimental results to enable a more comprehensive parameter analysis. The results indicate that the failure of the specimens always initiates from the steel profile flange and gradually extends to the external stainless steel tube. The initial stiffness, ultimate bearing capacity, and ductility of the specimens increase with decreasing diameter-to-thickness ratio and increasing embedded steel profile ratio. The strength of the embedded steel profile positively correlates with ultimate bearing capacity and ductility. Higher concrete strength improves ultimate bearing capacity but reduces ductility. Finally, a bearing capacity prediction model for ESUHPCFSST columns is proposed based on the experimental and finite element results, which guides the engineering application of such structures.

Computational analysis of structure manufactured by means of the steel framing system. Case study: industrial warehouse

A study is carried out between the traditional system of industrial warehouse construction, which is characterized using hot-rolled steel profiles, in comparison with the Steel Framing system, which uses low-thickness cold-formed steel profiles. Although the low-thickness profiles used in Steel Framing may generate mistrust, these profiles work by shape and not by mass. Steel Framing being a modern system, in our region it is not easy to find industrial warehouse constructed with low-thickness cold-formed steel profiles for the main and secondary elements, so this study not only focuses on the constructive aspects, but also contributes to understand the physical response of the Steel Framing system to different loads. Between the two mentioned systems, the seismic-resistant design of the industrial structure is also included to first check if it is possible to use the Steel Framing system in medium industrial warehouse, located in highly seismic areas, such as the coastal region of Ecuador. It has been proven that the Steel Framing system is resistant to high winds, earthquakes and other loads that are established in national and international regulations, and we proved that taking advantage of the effective properties of cold-formed profiles increases their resistance The results of drifts demonstrate the seismic resistance of the system, with the value of 0.00107 being the maximum value of inelastic drift obtained in the X direction, which represents only 5.37% of the value allowed in the standard.

Development of a Pavement-Embedded Piezoelectric Harvester in a Real Traffic Environment.

Road pavements are spread over large areas and convey various possibilities for energy sources such as high thermal gradients due to their materials and colors, wind corridors, large flat areas for solar harvesting, and heavy loading from traffic. The latest advances in road energy generation have been discretely implemented and have mainly focused on photovoltaic surface applications; other studies have explored the use of piezoelectric transducers with high stresses for better energy-production performance but limited life span. This study explores the stresses on pavement surfaces from traffic loading shockwaves that yield to the natural frequency vibration a piezoelectric harvester using a cantilever array. The passing vehicles triggered 16 piezoelectric sensors divided into four embedded steel profiles. The peak electrical power obtained in the experiment was 55.6 µW with a single transducer using a tip mass of 16 g. The proposed harvester demonstrated potential for applications in micro-generation of energy with limited infrastructure modification and high endurance under traffic loading over time. Its generation capacity is around 50 mWh a month with 16 piezoelectric cantilevers installed (for a commercial traffic volume of 1500 vehicles a day), enough to power a 200 m flashing LED raised marker strip to guide drivers for lane alignment during night shifts.

Sustainable Lifecycle of Perforated Metal Materials.

In an era of rapidly growing consumer demand and the subsequent development of production, light materials and structures with a wide range of applications are becoming increasingly important in the field of construction and mechanical engineering, including aerospace engineering. At the same time, one of the trends is the use of perforated metal materials (PMMs). They are used as finishing, decorative and structural building materials. The main feature of PMMs is the presence of through holes of a given shape and size, which makes it possible to have low specific gravity; however, their tensile strength and rigidity can vary widely depending on the source material. In addition, PMMs have several properties that cannot be achieved with solid materials; for example, they can provide considerable noise reduction and partial light absorption, significantly reducing the weight of structures. They are also used for damping dynamic forces, filtering liquids and gases and shielding electromagnetic fields. For the perforation of strips and sheets, cold stamping methods are usually used, carried out on stamping presses, particularly using wide-tape production lines. Other methods of manufacturing PMMs are rapidly developing, for example, using liquid and laser cutting. An urgent but relatively new and little-studied problem is the recycling and further efficient use of PMMs, primarily such materials as stainless and high-strength steels, titanium, and aluminum alloys. The life cycle of PMMs can be prolonged because they can be repurposed for various applications such as constructing new buildings, designing elements, and producing additional products, making them more environmentally friendly. This work aimed to overview sustainable ways of PMM recycling, use or reuse, proposing different ecological methods and applications considering the types and properties of PMM technological waste. Moreover, the review is accompanied by graphical illustrations of real examples. PMM waste recycling methods that can prolong their lifecycle include construction technologies, powder metallurgy, permeable structures, etc. Several new technologies have been proposed and described for the sustainable application of products and structures based on perforated steel strips and profiles obtained from waste products during stamping. With more developers aiming for sustainability and buildings achieving higher levels of environmental performance, PMM provides significant environmental and aesthetic advantages.

PEMANFAATAN BUILDING INFORMATION MODELLING (BIM) PADA PERANCANGAN STRUKTUR BAJA TERHADAP BEBAN GEMPA

This study focuses on designing the steel structure construction toward earthquake load, which uses Istana Qur’an as a research object. Modeling and designing the steel structural building by using two different software, SAP2000, and Tekla Structure. In the making process, the authors made presumptions on workload according to Indonesian Design Standards such as minimum design loads, seismic load design, seismic load for steel structure design, and joints in steel structure. Not only from a structural strength view for human safety but also the construction time and material cost are also able to be estimated which is becoming faster and more affordable compared to implementing the conventional method. As a full analysis result, in this steel design, there are six different steel profiles were used for steel building construction. For instance, IWF 440.300.11.18 as the column, IWF 350.175.7.11 and IWF 250.125.6.9 as the beams, IWF 200.100.5,5.8 as the gable roof frame, UNP 150.75.9.12,5 as purlin and L 150.150.15 as collar tie.

Fire Performance of Steel Profiles Covered with Self Compacting Concrete

Fire Performance of Steel Profiles Covered with Self Compacting Concrete

Investigation of an Effective Anchoring Length of CFRP Tapes Used to Strengthen Steel Thin-Walled Beams with a Rectangular Cross-Section Subjected to Four-Point Bending.

In order to design an optimal reinforcement of steel thin-walled beams with composite materials, it is worth analyzing two important, although often overlooked issues, which are the selection of the appropriate thickness of the adhesive layer and the effective anchoring length of the composite tape. This paper, which is part of a wider laboratory study devoted to the strengthening of thin-walled steel profiles, focuses on the second issue. The paper involves a description of laboratory four-point bending tests during which ten thin-walled steel beams made of a rectangular section with dimensions of 120 × 60 × 3 and a length of 3 m were tested. Two beams were taken as reference beams, and the other eight were reinforced using Sika CarboDur S512 carbon fiber composite tape, assuming four different effective anchorage lengths. The impact of the length of the anchoring of the composite tape on the value of the displacements and strains of the tested beams and on the value of the destructive load that caused tape detachment was analyzed. The following phase was numerical analyses carried out in the Abaqus program, which showed high consistency with the results of laboratory tests. In reference to the conducted tests, it was observed that the increase in the anchoring length of the composite tape has a slight impact on the change in the value of strains and displacements in the tested beams. Nevertheless, the increase in the effective anchorage length has a significant impact on the load value at which the composite tapes are detached from the surface of the steel thin-walled beam.

Development of a computational thermodynamics EERZ model for the improvement of hot rolled light steel profiles steel refining

Light steel profiles are steels with medium C, Mn and Si contents. In these steels internal cleanness is important for mechanical properties and surface quality, both during hot rolling and during the coating of the final product. Production costs of these steels are defined by the total heat time, from charging the Electric Arc Furnace (EAF) to starting continuous casting. Ladle furnace (LF) processing has a large influence on heat time and costs related to deoxidation, meeting composition requirements with a high yield of oxidizing alloying additions and proper rinsing to promote homogenization and cleanness. Thermodynamics and kinetics control how slag and steel oxidation levels evolve, as well as the evolution of the non-metallic inclusion population since at this stage primary oxides are the main inclusions. A model based on solid thermodynamic and kinetics fundamentals would be extremely useful for the producer of these steels, so that the evolution of the heat in the ladle furnace could be properly understood and, afterward, improve. In this work, we present the development of an “Effective Equilibrium Reaction Zone” (EERZ) for the LF processing of these steels, using a well-established thermodynamic database for metal and slags and a module of commercial computational thermodynamic software. We aim at demonstrating that these easily accessible and useable tools can be very effective to help in industrial process development. Thus, based on three selected industrial heats we adjust the kinetic parameters to describe the processes occurring for tapping from the EAF to releasing the heat for continuous casting. Volumetric mass transfer coefficients, heat transfer coefficients and other less critical variables are adjusted based on these heats and the model is then tested in seven further heats of the same steel grade. Results indicate that it is possible to achieve a good fit of the model to the industrial process and this helps identifying critical process variables to optimize the process schedule of these steels. Furthermore, we identify possible current limitations of the modeling strategy as suggested in the preliminary steps for the development of a EERZ model that may be coupled for on-line use, the support LF operators.

Experimental and Numerical Study of the Behavior of RC Shear Wall with Opening Using Concealed Stiffeners

A shear wall becomes weak when an opening is provided in it. It is important to provide some arrangement in the shear wall having an opening for recovering strength loss due to the opening. It may be recovered by providing some steel profiles around the opening or at weaker sections in the shear wall having an opening. At first, the identification of weaker sections in the shear wall having an opening is important and then, the wall can be made stronger as the shear wall without an opening by strengthening weaker sections. In the present study, the performance of a shear wall having an opening subjected to horizontal cyclic loading along the plane of the shear wall in the presence of concealed stiffeners is investigated. The reduced models of shear walls with openings were tested under axial and lateral load conditions. Load-carrying capacity, deformation behavior and strain behavior of shear walls were studied with experiments and the validation of the results was made with general-purpose finite element software ANSYS. Significant improvements were observed in strength, deformation and strain behavior of a shear wall having a central opening using concealed reinforced concrete (RC) stiffeners and steel tube stiffeners. KEYWORDS: Shear wall, Strength, Stiffness, Strain, Openings, Stiffeners.

Shear-slip constitutive model of screw-fastened connections and application in numerical analysis of built-up back-to-back cold-formed steel columns

In order to study shear-slip constitutive model of screw connections between cold-formed steel (CFS) profiles and its application in numerical analysis of CFS built-up columns, a total of 225 steel-to-steel screw-fastened connections were investigated under monotonic loads. The thicknesses of C-section steels and diameters of self-drilling screws were varied to study their effect on shear performance of connections. The experimental results show that the failure modes can be divided into three types, which include bearing failure of screw holes, shear failure of screws and pull-out of screws. Furthermore, the shear-slip constitutive model of screw-fastened connections was developed and then the methods for estimating stiffness parameters, strength parameters and displacement parameters were derived. In addition, the numerical models were put forward by applying the shear-slip constitutive model on basis of previous built-up back-to-back CFS columns tests. The results of numerical simulation are consistent with the previous test results by comparisons. The proposed shear-slip constitutive model can effectively simulate the shear-slip behavior of screws used in built-up back-to-back CFS columns.