Steel Sections Research Articles (Page 10)

Cold-formed steel (CFS) sections are used to construct medium and low-rise structures designed to carry small-scale loads. CFS sections are manufactured without the application of heat. Therefore, it is crucial to comprehend the properties of CFS sections which are exposed to fire or elevated temperatures. To simulate the real- time fire exposure, an ISO Standard fire curve was used to heat the CFS sections. The objective of the study is to assess the residual mechanical strength of exposed sections after the elevated temperature test. The study aims to compile data for forecasting the degeneration of elements and to ascertain whether the structural components can be reused or replaced. The CFS sections were subjected to different temperatures, and after heating, two cooling methods were used to bring down to room temperature. The characteristics of the retrieved specimens, taken from exposed CFS sections were assessed using a tensile coupon test. The residual properties such as ultimate strength, yield strength, and elastic modulus were examined and reported. The influence of heating and cooling is more pronounced from the test results. A reduction in the yield and ultimate strength was noticed, and it was found to decrease as the heating intensity increases for air and water cooling respectively. In the case of yield and ultimate strength, the strength reduction is critical beyond 60 minutes. The elastic modulus was also found to be reducing with a similar trend. Based on the test results, reduction factors are proposed for ultimate strength, yield strength and elastic modulus. Reduction factors obtained for yield strength under 60 minutes of heating for air and water cooling is 0.575 and 0.557 respectively. In 120 minutes, the values are 0.400 and 0.329. Reduction factors obtained for ultimate strength under 60 minutes of heating for air and water cooling is 0.586 and 0.566 respectively. For 120 minutes, the values are 0.331 and 0.313.

Finite element analysis and bearing capacity calculation of cross-shaped CFST columns under compressive load

Study on Detailing of Structural Steel Section on Lateral Behavior of SRC-RC Transfer Columns

A numerical study on a novel demountable cold-formed steel composite beam with profiled steel sheeting

I-section steel columns strengthened by wire arc additive manufacturing - concept and experiments

SummaryConcrete‐encased columns reinforced with one built‐up steel core are widely used as mega columns in high‐rise buildings. Due to the enormous size of the steel core, multiple steel segments have to be welded and spliced on‐site, which might inflict detrimental impacts on the integrity and ductility of the columns. To solve this practical issue, one method using multiple steel sections to replace one gigantic built‐up section is proposed. However, whether those columns reinforced with individual steel sections could have the same capacity as the ones reinforced with one steel core and whether the current design method relying on strain compatibility is still applicable to design such columns remain unknown. In this study, one column specimen reinforced with multiple steel sections is tested and the test results are utilized to calibrate finite element models. Afterward, finite element (FE) analysis is performed on concrete‐encased columns reinforced with multiple steel sections to numerically examine the load capacity of those columns. Based on the numerical analysis, a design method based on modified strain distribution is proposed. Numerical results indicate that concrete‐encased columns reinforced with multiple steel sections exhibit similar performance compared with the one reinforced with one steel core, showing great potential to be applied as mega columns in high‐rise buildings.

A novel confined concrete constitutive model for steel-reinforced concrete (SRC) columns with cross-shaped steel (CSS) sections is proposed. The model is based on the similar characteristics of descending branches in the stress–strain curves of confined and unconfined concrete (UCC), considering confinement degradation caused by buckling of the steel section or longitudinal reinforcement. The confined region of SRC columns with CSS sections was divided into four parts: highly steel-confined concrete (HSCC), partially steel-confined concrete (PSCC), stirrup-confined concrete (StCC) and UCC. Relevant effective confinement coefficient expressions were also derived. Simulations of existing tests showed that (a) the load–strain curves obtained using the modified stress–strain constitutive model agreed well with the experimental results, with the error in the descending branch less than 5%; (b) the HSCC region for SRC columns with CSS sections in the finite-element model was in good agreement with that in the proposed region division; (c) the simulation of confined concrete region boundaries for SRC columns with CSS sections were determined using plumb lines for improving the calculation efficiency.

This paper presents the parametric optimization of single-story steel buildings subjected to high loads. In the parametric study, high loads of snow and wind are determined for different altitudes up to 3000 meters above sea level. The Alpine region and the Eurocode 1 standard are considered. The discrete mixed-integer non-linear programming optimization is performed for different altitude alternatives. The optimization model for the steel structure is developed and used. The mass objective function of the structure is subjected to dimensioning and deflection constraints defined by the Eurocode standards. The modified outer-approximation and equality-relaxation algorithm is applied. The optimal results obtained include the minimal possible mass of the structure, the optimal topology, the steel sections and the steel grade. In the case of a medium-sized single-story steel building, it was found that the structural mass increases by 2.7 times and the number of main portal frames increases by 80 % when the altitude of the building site is increased from 500 to 3000 meters above sea level. The optimal results clearly show how the structural mass and cross-sections increase with increasing load.

Quantification of seismic performance factors of mixed concrete/steel buildings using the FEMA P695 methodology

Structures known as modular buildings are made in factories and then moved to construction sites, where they are assembled. The efficacy of modular structures under many uncertainties has to be thoroughly investigated as demand rises; fire is one such uncertainty. The purpose of this study is to ascertain how high temperature affects the components of modular constructions. In the current study, hollow steel columns and beams were taken into account as components of a modular construction. Using ABAQUS, several situations were examined depending on the span length to determine the important locations of the members. Experimental research was conducted on the critical regions identified by the analysis, and the results were contrasted with those of the analysis. A high-temperature localized heating furnace was used for the experimental testing. The findings demonstrated that for spans of 250 mm and 500 mm, the central area of the beams was essential, and the load-carrying capacity was six times less than that of heating at the extremities of the beams. Similar to the beams, columns exhibited less fluctuation than the beams and were weaker in the bottom area when exposed to high temperature. When compared to other places, the capacity was reduced by 1.1 times, and in Case 1, the capacity reduction with regard to loading was 1.68 times greater. Doi: 10.28991/CEJ-2024-010-03-014 Full Text: PDF

To investigate the flexural performance of steel-continuous-fiber composite bar (SFCB) and fiber-reinforced polymer (FRP) bar hybrid-reinforced sea-sand concrete (SSC) beams, a total of 21 SSC beams were numerically studied. The concrete damaged plasticity model (CDPM) and FRP brittle damage model were adopted, and the bond-slip behavior between the reinforcement and concrete was considered. Parametric studies were conducted to study the effects of the SSC strength, sectional steel ratio of the SFCB, core steel bar yield strength of the SFCB, out-wrapped FRP elastic modulus of the SFCB, and the ultimate tensile strength of the SFCB on the flexural performance of the beams. The results indicate that increasing the SSC strength and out-wrapped FRP modulus enhanced the bearing capacity and stiffness but reduced the ductility, shifting failure from concrete crushing to FRP bar fracture. A higher SFCB sectional steel ratio markedly improved the flexural stiffness, transforming the load–deflection curve. Elevated core steel bar yield strength maintained the cracking load and deflection while increasing the yield and ultimate loads. For SFCB fracture, higher ultimate tensile strength in the out-wrapped FRP enhanced the ultimate load and deflection, but not in concrete crushing failure. In addition, three failure modes were defined based on the proper assumption, with the proposed bearing capacity formulas aligning well with the FE results.

Influences of structural size and confinement effect on the axial compressive behavior of SCFST columns

Cold-formed steel (CFS) sections constructed with high-strength steel have gained prominence in construction owing to their advantages, including a high strength-to-weight ratio, shape flexibility, availability in long spans, portability, cost-effectiveness, and design versatility. However, the thin thickness of CFS members makes them susceptible to various forms of buckling. This study focuses on addressing and mitigating different types of buckling in columns and beams by manipulating the lip length (d) and the ratio of inside radius to thickness (Ri/t) in CFS C-sections. To achieve this objective, a comprehensive analysis involving 176 models was conducted through the Finite Element Method (FEM). The findings reveal that an increase in lip length leads to a corresponding increase in critical elastic buckling load and moment (Pcrl, Pcrd, Pcre, Mcrl, Mcrd, and Mcre). It is recommended to utilize a lip length greater than or equal to 15 mm for both columns and beams to mitigate various buckling types effectively. Conversely, an increase in the ratio of inside radius to thickness (Ri/t) results in an increase in critical elastic local buckling load (Pcrl) and moment (Mcrl). Thus, lip length (d) significantly influences column and beam buckling, whereas Ri/t exhibits a relatively impactful effect. Subsequently, the experimental test results were used to verify finite element models. These insights contribute significant knowledge for optimizing the design and performance of CFS C-sections in structural applications.

Three-dimensional peridynamic modeling of deformations and fractures in steel beam-column welded connections

Abstract Shape memory alloys (SMAs) have found several applications in earthquake‐resilient structures. However, because of high material costs, their implementation on industry projects is still limited. Developing design approaches that minimize the use of expensive SMAs is critical to facilitating their widespread adoption in real structures. This paper proposes a performance‐based seismic design optimization procedure for self‐centering steel moment‐resisting frames (SC‐MRFs) with SMA‐bolted endplate connections. The topology optimization uses a metaheuristic algorithm to minimize the frame's total cost, including the initial construction and expected repair costs. The design variables are the steel beam and column sections, SMA connection properties, and the topology of the SMA connections. Different constraints are considered, such as the constructability of the chosen steel sections, member strengths, performance‐based design, Park‐Ang damage index, and strong‐column weak‐beam requirements. Furthermore, the seismic safety of optimal designs is assessed by calculating adjusted collapse margin ratios according to FEMA‐P695. An illustrative optimization study using three‐ and nine‐story SC‐MRFs is presented. The optimal SC‐MRFs are then assessed in terms of cost and seismic performance. The results confirm the effectiveness of the proposed optimum design, which minimizes the use of SMAs while ensuring improved seismic performance. The case studies show that the optimal placement of SMA connections can reduce the total cost by up to 71% and 61% for the three‐ and nine‐story SC‐MRFs, respectively, compared to nonoptimal frames. Moreover, the optimal SC‐MRFs exhibit more uniform drift distributions, lower residual story drifts by up to 96%, and increase collapse capacity by up to 102%.

The composite concrete-encased steel (CCES) column member is made by the steel section embedded and covered in concrete from all sides. Due to the ability of the composite sections to bear heavy loads while using smaller sections, CCES columns have been widely used. Analytical studies on the CCES columns’ behavior using crushed dolomite coarse aggregate (CDCA) with different shear connectors (SCs) types/shapes and sizes under axial loads are described here. This study also aims to evaluate the current design methods to determine the ultimate capacity of the CCES with CDCA concrete columns using nine available codes. The results show that the finite element (FE) analysis could accurately predict the ultimate capacity of the CCES columns; the column’s capacity improved by about 41.75% as fcu increased by 60%. Increasing the IPE-shaped steel strength (fss) strategy is not very effective and gives brittle behavior even though enhancing the fss improves the capacity. The column's capacity increased as the tie stirrups and steel bars ratios increased. The column’s capacity increased by about 17.63%, as steel bars ratios increased by 155.49%. The efficiency factors increased slightly as tie stirrups were raised but slightly decreased as steel bar ratios increased. Using the SCs system increases the columns’ capacity by an average value of about 4.9% of the specimen without SCs. The computed capacities using the nine available codes are conservative and safe. The closest estimates made by the YB9082-06 code are 26% less on average than the test results; in contrast, the safest predictions made by the ECP-LRFD code are 68% less, on average, than test results.Graphical

The Effects of Corrosion Damage on the Square Hollow Steel Section (SHSS) Profiles: An Experimental and Numerical Investigation

Numerical simulation of corroded circular hollow section steel columns: A corrosion evolution approach

Mechanical characteristics and stability analysis of an innovative type of steel–concrete composite support in shallow-buried excavation tunnels

Behavior of concrete-filled double steel tube stub columns under partial compression