Steel Sections Research Articles

Cracking up to 1.5 mm was predicted for two zones of the reinforced concrete (RC) piles of a 100-y design life major new road infrastructure project in Australia, where the piles had moved more than the structural design limits during construction. In-ground exposure conditions for the piles were saline groundwater, and conventional carbon steel reinforcement at crack locations was therefore exposed to higher levels of chloride than would be expected during the future 100-y design life of the structure. To determine whether the RC substructure elements of this section of the project could meet a 100-y design life without remedial works in aggressive, marine salinity, in-ground exposure conditions, desktop deterministic corrosion propagation modeling at crack locations was undertaken during construction. Both microcell corrosion and macrocell corrosion can occur for conventional steel in cracked marine concrete. Each of these forms of corrosion was examined in turn for the steel reinforcement in high-performance, blended cement-based, 75 mm minimum cover, cracked concrete (of anticipated surface crack widths of up to 1.5 mm) under buried (in rock), saline (essentially seawater), groundwater conditions. While microcell and macrocell corrosion may act together, it was proposed that macrocell corrosion takes over and dominates until ongoing (long-term) corrosion means that anodes will extend, and macrocell corrosion will eventually evolve into microcell corrosion. Microcell section losses were also judged not to be added to predicted macrocell section losses. The maximum predicted section losses due to pitting were therefore considered as worst-case for a 100-y design life period. Two (2) microcell deterministic corrosion models and one (1) macrocell deterministic corrosion model were considered during the desktop assessment, namely: for microcell corrosion: oxygen diffusion control and crack resistance control models, and for macrocell corrosion assessment: an oxygen diffusion control model. Microcell corrosion deterministic desktop modeling predicted the worst-case likely local reinforcing steel section loss for affected RC pile tops and pile toes to be 2.1 mm at 0.15 mm to 0.7 mm surface cracked locations over the 100-y structure design life. For 0.7 mm to 1.5 mm cracked locations, microcell corrosion deterministic modeling then predicted the worst-case likely local reinforcing steel section loss for affected RC pile tops and pile toes to be 3.2 mm over the 100-y structure design life. Macrocell corrosion deterministic desktop modeling, on the other hand, predicted the worst-case likely local section reinforcing steel loss for affected RC pile tops and pile toes in both 0.15 mm to 0.7 mm and 0.7 mm to 1.5 mm surface cracked concrete to be 7.1 mm over the 100-y structure design life. Because of the desktop deterministic corrosion propagation modeling, a local reinforcing steel section loss (not full circumference) of up to 7.1 mm was therefore allowed by the structural designers for pile top and pile toe sections over the 100-y design life of the project. Furthermore, the desktop corrosion assessment provided the structural designers, constructors, project verifiers, and structure owner authority with sufficient information to make suitably informed decisions and approve the 100-y durability design for the structure.

This study analyzed the connection using finite element (FE) simulations and nonlinear analysis to determine its moment resistance and mode of failure. In this work, FEA (finite element analysis) is employed to analyze the triangular web profiled (TRIWP) steel section as a beam element and extended end plate connection. The connection model has been developed with different thicknesses of extended end plate, beam flange, and beam web, and these parameters were analyzed to determine the relationship between all three cases with the failure connections and moment-rotation curve. Furthermore, the results obtained from the analysis of using extended end plate connections have been compared with previous studies where flush end plate connections are used to compare the behavior of the two end plates' connections. Twelve LUSAS analysis models were used, varying parameters such as the thickness of the flange beam, web beam, and end plate. Results indicated that an increased end plate thickness led to a higher moment resistance. A comparison of the moment resistance between the extended end plate and flush end plate connections, from a previous study, showed a difference of 48%. This finding is attributed to the extended end plate's ability to sustain a higher moment compared to the flush end plate. Therefore, the extended end plate connection is stronger than the flush end plate connection. Failure modes showed that buckling occurred at the top flange, which was similar for both types of connections. The use of a triangular shape is used to create contrast as this is prominent from the other shapes used commonly in web design.

Abstract With the increasing use of partially encased composite (PEC) columns in construction, the risk of fire also rises. The post‐fire performance of PEC columns is crucial for their rehabilitation and reuse. A finite element analysis (FEA) model was developed in this study to investigate the behavior of PEC columns after exposure to combined loading and full‐range fire, including ambient temperature loading, heating and cooling with constant load, and post‐fire loading to failure. The load ratio, heating time ratio, cooling rate, sectional perimeter, slenderness ratio, steel ratio, reinforcement ratio, load eccentricity, cement mortar thickness, yield strength of steel section, and strength of concrete on the post‐fire performance were analyzed. A design equation for the residual load‐carrying capacity of PEC columns after a fire was developed. The results show that the load‐carrying capacity of a PEC column with a cross‐section of 400 × 400 decreased by 14.9%, while the vertical deformation increased by 82.4% after the fire compared to those at ambient temperature. After the fire, the proportion of the external load shared by the steel section in the PEC column decreased from 56% at ambient temperature to 32%. The heating time ratio, load ratio, slenderness ratio, and cube strength of concrete are the primary factors that have the most significant influence on the post‐fire load‐carrying capacity of PEC columns. Additionally, a slower cooling rate exacerbates thermal damage to the structure and further diminishes its residual load‐carrying capacity. The calculated results of the residual load‐carrying capacity agree well with the FEA results.

This study investigates the thermal distribution and its effect on the material characteristics and the distribution of hoop residual stresses in welds with varying proximity distances, made from S355 G14 + N steel circular hollow sections. Girth welds have been shown to be performed in close proximity in structures subjected to dynamic loading, and these welds can have residual stresses that can have a significant effect on fatigue strength and overall structural integrity. It is known that the thermal effects from the welding process can have different effects on the residual stress levels as well as the materials microstructure and mechanical properties depending on the proximity. This study aims to evaluate the material characteristics and residual stress levels in the weld proximity regions and their potential impact on fatigue performance. Three hollow cylindrical sections, each with a diameter of 219.1 mm, were welded at proximity distances of 5 mm, 15 mm, and 50 mm for analysis, thermal camera to verify the magnitude of heat distribution. In order to investigate the microstructure and mechanical characteristics across the proximity welds hardness tests and scanning electron microscope (SEM) is employed. Subsequently, by applying the sectioning method three strips were cut from each section and analyzed. The amount of residual strains relieved was used as a measure to evaluate the level of residual stresses. Strain gauges were employed to measure the surface hoop residual stresses relived during the extraction of the strip specimens. The results demonstrated that proximity distance and welding procedure have a significant influence on the distribution of residual stresses. The residual stresses measured in the extracted samples were consistent with those observed in full girth welds from previous studies, showing tensile stresses in the weld, and compressive stresses on each side of the weld. This stress profile remained consistent across the different proximity distances. In addition, at a proximity distance of 50 mm, compressive residual stresses increased significantly in the proximity region. Notably, the results are showing higher tensile stresses in the heat affected zone on the side of the last weld near the final weld bead raising concerns about the weld’s integrity under cyclic loading. These findings suggest that controlling thermal cycles and weld sequence is crucial for optimizing residual stress distribution and improving the fatigue performance of girth-welded structures with welds at close proximity.

Purpose The universal beam is widely used as construction material due to its excellent strength-to-weight ratio but high slenderness ratio in the web steel section prone to lateral-torsional buckling (LTB) failure. To improve LTB resistance, the incorporation of modified foamed concrete (FC) in partially encased steel beam (PESB) is proposed. The FC-encased web section of steel beam promotes overall weight reduction and increases its specific strength. However, FC has substantially low strength, but incorporation of siliceous material (such as rice husk ash [RHA]) offers pozzolanic activity to offset the low strength in FC. This study explores the use of a modified FC to encase steel beam, where 40% of fine aggregate is replaced with RHA (hereafter referred to as RHA-FC) to enhance the load-bearing capacity and torsional rigidity. Addition of RHA mitigates the extraction of natural resource due to the reduction of fine aggregate consumption. This study aims to investigate the material properties of RHA-FC and measure the flexural strength of RHA-FC PESB. Design/methodology/approach The experimental work was performed to assess the compressive strength, splitting tensile strength, modulus of elasticity, Poisson ratio and fracture energy of plain FC, RHA-FC and normal concrete (NC). In addition, the flexural strength of PESB was evaluated through the four-point bending test. Findings RHA-FC improved the mechanical properties compared with the FC counterparts. Nevertheless, less satisfactory performance was seen in RHA-FC compared with NC. RHA-FC PESB achieved average 17.87% enhancement in ultimate bending moment compared with bare steel beam counterparts and can reduce lateral torsional buckling with associated zero torsional angle. Originality/value RHA-FC PESB substantially enhances stability and performance and offers a promising alternative in construction applications.

There are often no technical specifications and technological maps for the installation of built-in shelters in existing structural and planning schemes of buildings. Atypical architectural and structural solutions for protective structures can be implemented using monolithic or precast concrete and steel-reinforced concrete structures. Due to the two-stage technology for the manufacture of precast steel reinforced concrete slabs, the geometric characteristics of their composite cross-sections change during the manufacturing process. Changes in cross-sections of building structure elements during the manufacturing process are commonly referred to as genetic nonlinearity. At the same time, in most cases, the change (increase due to the monolithic upper concrete shelf) of the cross-section of a steel-reinforced concrete slab element occurs under different deformations in its components: the existing deformations in the steel part from the dead weight of the monolithic concrete slab and the absence of deformations in the monolithic concrete slab. This fact is the reason for the bilinear appearance (discontinuity of the linear appearance at the border of the upper shelf of the steel I-beam and the bottom of the concrete slab) of the diagram of strains in the cross section of steel reinforced concrete slabs. It is possible to avoid the genetic nonlinearity of steel reinforced concrete slabs by installing temporary supports for steel beams during the concreting of the monolithic slab or by constructing the monolithic slab on inventory temporary formwork. By installing the above-mentioned temporary posts, it is possible, on the contrary, to achieve favorable pre-stresses in the components, which can be called self-stressing of such slabs. During the experimental loading of a fragment of a pre-stressing steel-reinforced concrete slab, the increase in relative deformations along the height of the cross-section, taking into account the pre-bending of steel beams, is similar to those predicted during the theoretical analysis of the stress-strain state of such beams. Taking into account the pre-stressing of the steel beams allowed us to reduce their cross-section from a rolled I-beam № 45 to an I-beam № 36 with a strip along the bottom girdle, which reduces steel consumption by 11.1 %.

In the construction field, using Steel-Reinforced Concrete (SRC) columns is difficult due to the need for rebars and stirrups. Additionally, the casting of concrete is also challenging due to the presence of reinforcements. The main objective of this work is to investigate the seismic capacity of Hybrid-Fiber Concrete-Enhanced Steel (HFCES) column specimens without any longitudinal steel bars or stirrups. Since the reinforcements are eliminated, the concrete cover becomes smaller, and the size of the steel section can be increased to provide the same flexural strength. To keep the concrete crack at a low-level under large deformation, fiber concrete is used. Initially, this study evaluates the effects of synthetic hybrid fibers, including alkali-resistant glass fiber (AR-GF) and polypropylene fiber (PPF), on the strength and workability development of concrete. Based on the findings from previous studies, various mixing proportions of HFC are determined. Subsequently, the mixture that optimizes both workability and flexural strength is selected based on experimental data. An experimental program, consisting of four column specimens, is conducted to analyze the seismic capacity behavior of the HFCES columns in a static-cyclic loading test. A comparison with traditional SRC column specimens reveals the advantages of HFCES columns, further confirming their practical application.

This paper investigates the prediction of buckling and flexural behavior in cold-formed steel (CFS) sections, specifically focusing on built-up SupaCee and lipped Cue (C) sections through experimental analysis. CFS beams with staggered slotted perforations are being used more often in light gauge steel construction to improve fire and energy performance. However, CFS beams’ load-bearing capability is compromised due to the lack of conclusive assessments in previous studies regarding design expressions for predicting the structural performance of slotted perforated CFS flexural elements. Parameters like the size of CFS beams, spacing between groups, rows of slots, and yield strength are crucial criteria. The study delves into the effects of dimensions of CFS beams, rows and row groupings of slots, staggered slotted perforations, and yield strength on the potential for local buckling of perforated staggered slotted CFS beams during bending. Additionally, a comprehensive nonlinear finite element modeling is conducted. The findings indicate that geometric parameters have nearly equal contributions to the flexural capacity and the specimens’ deflection.

Corrosion protection in reinforced concrete structures exposed to aggressive environments remains a critical challenge in civil and architectural engineering. One promising approach involves the application of corrosion-inhibiting monolayers on the reinforcement, such as those formed using 4-aminobenzoic acid. Two methods have previously been employed to generate these monolayers: one relying on the adhesion of an organic compound and the other utilising an externally modified approach via electrolysis. This study assesses the influence of this treatment on the steel-concrete bond strength and durability, both critical properties for the structural performance of reinforced concrete under service conditions. For this purpose, pull-out tests were performed on specimens subjected to load-unload cycles to analyse bond behaviour and monolayer integrity. The results indicate that these treatments do not adversely affect the bond strength between reinforcement and concrete. Furthermore, the rebars treated with the inhibitor exhibit less corrosion damage than the untreated rebars. This fact is particularly significant in the rebars treated using the natural adhesion method, with the steel section loss being 32-37% lower than in the untreated rebars. These findings support the feasibility of applying this treatment without compromising structural functionality.

Glass Fiber Reinforced Polymer (GFRP) bars have gained popularity as a corrosion-resistant alternative to traditional steel reinforcement in Reinforced Concrete (RC) elements. This study investigates the flexural behavior of PRC panels reinforced with GFRP bars. The study variables included the GFRP reinforcement ratio and the number of embedded steel section distributions. Six concrete panels were fabricated, each measuring 2500 mm in length, with a rectangular cross-section of 750 mm in width and 150 mm in thickness. All panels were reinforced with GFRP bars and divided into two groups based on the reinforcement ratios of 0.532% and 0.266%. For each group, one panel served as the control specimen, while the remaining two were internally strengthened with embedded steel box sections, one with 2 steel sections and the other with 4 sections. The parametric study highlighted the effects of the reinforcement ratio and the inclusion of internal I-section steel shapes on the flexural performance of the panels. Compared to non-strengthened control slabs, the addition of steel elements significantly improved the structural performance, as evidenced by reductions in deflection, strains, and crack widths, as well as an increase in the ultimate load capacity and flexural stiffness at the ultimate loading stage. These findings underscore the effectiveness of combining GFRP reinforcement with embedded steel shapes to enhance the structural performance of PRC panel slabs.

This study investigates the behavior of concrete-encased castellated steel beams featuring various aperture geometries and shear stud connector configurations. Five Composite Castellated Beam (CCB) specimens were tested under two-point loading conditions, including one control specimen with a solid steel section and four specimens with castellated steel beams encased in Normal-Strength Concrete (NSC). The castellated beams featured either Hexagonal (H) or Rectangular (R) openings, and the shear stud connectors provided either Full (F) or Partial (P) interaction between the steel and concrete components. The research objectives were to determine the maximum load capacity for each sample under applied loads, analyze the resulting deformations, and assess the impact of the opening shape and shear connections on the beam performance. The results showed that the H opening improved the load-bearing capacity by 19% and reduced the deflection and horizontal displacement by 21.47% and 12.86%, respectively, compared to the R opening sample. Specimens with F interaction exhibited a higher load capacity and lower deflection and horizontal displacement than those with P interaction. The F configuration increased load tolerance by 2.44% and decreased the deflection and horizontal displacement rates by 4.17% and 5.86%, respectively, relative to the P configuration. The findings demonstrate the influence of aperture geometry and shear connections on the structural performance of concrete-encased castellated steel beams, providing insights for optimizing their design in composite construction.

Abstract The high thermal conductivity of steel, combined with its rapid degradation in mechanical properties with increasing temperature, makes it vulnerable to fire. Fire protection materials are effectively designed to control the temperature rise within steel members. This paper is a companion to a previous numerical analysis study on protected square hollow section (SHS) steel columns using thermally enhanced gypsum-based mortars. It offers a more detailed numerical investigation into the thermal performance of different gypsum-based mortar compositions used as a passive fire protection material for different types of steel columns. Firstly, finite element models for SHS steel columns were developed and verified against data from previous fire resistance tests. Then, a parametric study was conducted to explore how factors like fire protection thickness and composition, cross-section (square, rectangular, and H-shaped sections), steel tube thickness, column slenderness, and applied load level (serviceability load states) affect their fire performance under the ISO-834 standard fire curve. Comparisons were made between numerical results and current design methods from Eurocodes. It was observed that existing design methods excessively underestimate the actual fire resistance of protected columns, particularly for class-4 cross-sections especially when mortars with highest thermal insulation capacity are used. Moreover, the thermal properties of fire protection mortars should be considered in the structural steel temperature prediction as a function of temperature during fire conditions. Based on the study’s findings, modifications to current design methods for predicting the temperature evolution of columns as a function of the cross-sections and fire protection compositions, were presented with enhanced accuracy. These proposed modifications can potentially contribute to future development in Eurocode and improved fire resistance predictions.

Sustainable construction of ecofriendly infrastructure has been the priority of worldwide researchers. The induction of modern technology in the steel manufacturing industry has enabled designers to get the desired control over the steel section shapes and profiles resulting in efficient use of construction material and manufacturing energy required to produce these materials. The current research study is focused on the optimization of steel building costs with the use of pre-engineered building construction technology. Construction of conventional steel buildings (CSB) incorporates the use of hot rolled sections, which have uniform cross-section throughout the length. However, pre-engineered steel buildings (PEB) utilize steel sections, which are tailored and profiled based on the required loading effects. In this research study, the performance of PEB steel frames in terms of optimum use of steel sections and its comparison with the conventional steel building is presented in detail. A series of PEB and CSB steel frames is selected and subjected to various loading conditions. Frames were analyzed using Finite Element Based analysis tool and design was performed using Indian standards design specifications. Comparison of the frames has been established in terms of frame weights, lateral displacements (sway) and vertical displacements (deflection) of the frames. The results have clearly indicated that PEB steel frames are not only the most economical solution due to lesser weight of construction but also have shown better performance compared to CSB frames. Key Words: sustainable; pre-engineered; conventional steel building; design; built-up sections; optimizations; minimum weight

This study investigates a novel steel grid shear wall (SGSW) structure with lightweight and discrete lateral-resistance members, focusing on its structural behavior in lateral resistance. By comparing the characteristics of the thin steel plate shear wall, the mechanism of the steel grid components in both the tension zone and compression zone was briefly described. The formulas of lateral-resistant capacity and initial stiffness of the SGSW were derived through the static equilibrium method. Then, the influence laws of the span–height ratio, steel member spacing and section size of the steel members on the lateral-resistant performance of the SGSW were determined through a parametric analysis. In addition, the accuracy of the calculation formula was validated. The results showed that the strains of the steel grid components in different positions were all the same when the bending stiffnesses of the edge members were significantly large. The lateral-resistance capacity of the SGSW increased with the span-to-height ratio, while it decreased as the spacing between the steel components increased. Compared with the effects of web height, web thickness and flange width, increasing the flange thickness exhibited the best effects on improving the lateral capacity. As the flange thickness increased from 7 mm to 13 mm, the lateral-resistant capacity showed an improvement of 35.45%. Additionally, the formula derived in this study demonstrated high accuracy and reliability, with the error not exceeding 8% between the formula calculation and the simulation results.

Abstract Seismic‐damaged reinforced concrete (RC) frames are required to be quickly repaired after the earthquake, and methods to strengthen the local structures and improve the seismic capacity of the whole structure are supposed to be considered. Considering the stress characteristics and failure mode of the RC frame in the earthquake, the column was partially strengthened with wrapped angle steel and batten plates, and then the whole frame was reinforced with the steel plate, diagonal bracing, and V‐shaped buckling restrained brace (V‐shaped BRB). A quasi‐static test was conducted on the RC frame after strengthening to study the seismic performance. The results showed a great improvement in the seismic performance of the strengthened RC frames, according to the seismic requirements of “strong joints and weak members; strong columns and weak beams.” The bracket and steel plate were destroyed before the frame, effectively avoiding the premature destruction of the main frame. The bearing capacity, initial stiffness, ductility, and cumulative energy dissipation of the strengthened RC frames were significantly better than those of the unreinforced. The bearing capacity and stiffness of the strengthened RC frames deteriorated slowly. The failure of strengthened RC frames was caused by cumulative damage. The seismic performance and ductility of the RC frame strengthened by the V‐shaped BRB were better than those strengthened with the other two methods due to its multiple energy dissipation capacity. Considering the seismic behavior and failure mode of the strengthened RC frames, the V‐shaped BRB was recommended for strengthening. Parameter analysis was conducted for an in‐depth study of the seismic performance of strengthened RC frames. The results indicated that the most effective way of improving the seismic performance of RC frames damaged in the earthquake and strengthened with V‐shaped BRB was to increase the thickness of the gusset plate. As the increase of axial compression ratio, the energy dissipation capacity of the frames strengthened with the three methods decreased to some extent.

Enhancing the Behavior of Concrete Beams Reinforced with FRP Bars Using Embedded Steel Sections and Ultra-high-performance Strain-Hardening Cementitious Composite

Combined with the location and characteristics of the high-altitude structural beam of the Daduhui project, the scheme of erecting large section steel beam as the formwork support platform is finally selected, through the detailed comparative analysis of the application of different load matrices. The scheme determines the key control points in the construction of high-altitude structural beam, and proves that the formwork supporting construction scheme can provide reliable support for high-altitude structural beam through engineering practice. Technically, this structural form is concise, safe, reliable, economical and reasonable, and easy to install. It not only saves the amount of steel pipe support, effectively shortens the installation period of formwork support, but also the section steel can be reused, reducing the cost. In addition, the technology also solves the construction problems of high-altitude beam and slab, and provides a valuable reference for other similar projects.

Experimental and numerical study of membrane residual stress in high-strength steel welded flat panel stiffened plate

Evaluating the Efficacy of Shear Connectors in H Steel Sections Embedded in Concrete

Steel-concrete-steel sandwich composite pylons for cable-stayed bridges: Structural behaviour of cable anchorage