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11 – 20 of 163Fatimah De'nan, Nor Salwani Hashim and Lim Cheng Kuan
Tapered section can resist maximum stress at a single location while the stresses are considerably lower at the rest of the member; therefore, it could have higher structural…
Abstract
Purpose
Tapered section can resist maximum stress at a single location while the stresses are considerably lower at the rest of the member; therefore, it could have higher structural efficiency compared to conventional section. It could also satisfy functional requirements while reducing weight and cost in many fields of civil construction. Perforation in the steel section also eases the integration of Mechanical and Electrical (M&E) services such as ventilation pipes and electrical cables within the structural depths of the beam. In this analysis, the structural efficiency of tapered steel section with perforation under lateral-torsional buckling behaviour is investigated.
Design/methodology/approach
A total of 81 models are analysed using LUSAS software and five variables are investigated which involved perforation sizes, perforation shapes, perforation layout, tapering ratio and flange and Web thickness. Buckling moment is obtained from the analysis results in LUSAS software, while self-weight and structural efficiency are manually calculated.
Findings
Perforation size of 0.75 D has the highest structural efficiency, although it can withstand a smaller buckling load. This is due to its lower self-weight compared to other perforation sizes. The square perforation shape also has the highest structural efficiency compared to circular perforation and diamond perforation. An increment of percentage in structural efficiency of the square perforation shape with 0.75 D is the highest at 3.07%. The circular perforation shape with 0.75 D (Open-Open-Open perforation layout) has the highest increment of percentage in structural efficiency which is 2.37%. The tapering ratio of 0.3 is the most efficient and an increment of percentage in structural efficiency is 114.36%. The flange thickness of 0.02 m and Web thickness of 0.015 m has the highest structural efficiency at 45.756 and 29.171, respectively.
Originality/value
In conclusion, a section should be able to resist the large buckling moment and has a lower self-weight to achieve high structural efficiency.
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Mehdi Kashani, Laura N Lowes, Adam J Crewe and Nicholas A Alexander
A new modelling technique is developed to model the nonlinear behaviour of corrosion damaged reinforced concrete (RC) bridge piers subject to cyclic loading. The model employs a…
Abstract
Purpose
A new modelling technique is developed to model the nonlinear behaviour of corrosion damaged reinforced concrete (RC) bridge piers subject to cyclic loading. The model employs a nonlinear beam-column element with multi-mechanical fibre sections using OpenSees. The nonlinear uniaxial material models used in the fibre sections account for the effect of corrosion damage on vertical reinforcing, cracked cover concrete due to corrosion of vertical bars and damaged confined concrete due to corrosion of horizontal tie reinforcement. An advance material model is used to simulate the nonlinear behaviour of the vertical reinforcing bars that accounts for combined impact of inelastic buckling and low-cycle fatigue degradation. The basic uncorroded model is verified by comparison of the computation and observed response of RC columns with uncorroded reinforcement. This model is used in an exploration study of recently tested reinforced concrete components to investigate the impact of different corrosion models on the inelastic response of corrosion damaged RC columns.
Design/methodology/approach
A series of pushover and cyclic analyses on a hypothetical corroded RC columns are conducted. The impact of corrosion on reinforcing steel and concrete is modelled. The influence of cyclic degradation due to low-cycle fatigue is also modelled.
Findings
(1) Corrosion has a more significant impact on ductility loss of RC columns than the strength loss (plastic moment capacity). (2) It was found that the flexural failure is initiated by buckling of vertical bars and crushing of core concrete which then followed by fracture of bars in tension. (3) The analyses results showed that for seismic performance and evaluation of existing corroded bridges monotonic pushover analysis is insufficient. The cyclic degradation due to low-cycle fatigue has a significant influence on the response of corroded RC columns.
Originality/value
The finite element developed in this paper is the most comprehensive model to date that is able to capture the onlinear behaviour of corroded RC columns under cyclic loading up to complete collapse.
Mohammad Zaman Kabir and Mehdi Parvizi
The purpose of this paper is to focus on the influences of residual stresses which were induced during roll-forming sections on lateral-torsional buckling of thin-walled…
Abstract
Purpose
The purpose of this paper is to focus on the influences of residual stresses which were induced during roll-forming sections on lateral-torsional buckling of thin-walled cold-formed steel channel and built-up I-sections beams. Built-up I section is made up of two back-to-back cold-formed channel beams. In this direction, at the primary stage, the roll-forming process of a channel section was simulated in ABAQUS environment and the accuracy of the result was verified with those existing experiments. Residual stresses and strains in both longitudinal and circumferential transverse directions were extracted and considered in the lateral-torsional buckling analysis under uniform end moments. The contribution of the current research is devoted to the numerical simulation of the rolling process in ABAQUS software enabling to restore the remaining stresses and strains for the buckling analysis in the identical software. The results showed that the residual stresses decrease considerably the lateral-torsional buckling strength as they have a major impact on short-span beams for channel sections and larger span for built-up I sections. The obtained moment capacity from the buckling analysis was compared to the predictions by American Iron and Steel Institute design code and it is found to be conservative.
Design/methodology/approach
This paper has explained a numerical study on the roll-forming process of a channel section and member moment capacities related to the lateral-torsional buckling of the rolled form channel and built-up I-sections beams under uniform bending about its major axis. It has also investigated the effects of residual stresses and strains on the behaviour of this buckling mode.
Findings
The residuals decrease the moment capacities of the channel beams and have major effect on shorter spans and also increase the local buckling strength of compression flange. But the residuals have major effect on larger spans for built-up I sections. It could be seen that the ratio of moment (with residuals and without residuals) for singly symmetric sections is more pronounced than doubly symmetric sections. So it is recommended to use doubly symmetric section of cold-formed section beams.
Originality/value
The incorporation of residual stresses and strains in the process of numerical simulation of rolled forming of cold-formed steel sections under end moments is the main contribution of the current work. The effect of residual stresses and strains on the lateral-torsional buckling is, for the first time, addressed in the paper.
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Charis Apostolopoulos, George Konstantopoulos and Konstantinos Koulouris
Structures in seismic areas, during their service lifetime, are subjected to numerous seismic loads that certainly affect their structural integrity. The degradation of these…
Abstract
Purpose
Structures in seismic areas, during their service lifetime, are subjected to numerous seismic loads that certainly affect their structural integrity. The degradation of these structures, to a great extent, depends on the scale of seismic events, the steel mechanical performance on reversal loads and its resistance to corrosion phenomena. The paper aims to discuss these issues.
Design/methodology/approach
Based on the experimental results of seismic steel behavior S400 (BSt III), which was widely used in the past years, a prediction study of seismic steel behavior was conducted in the current study. This prediction on behavior of both reference and corroded steel was succeeded through a simulation of experimental low cycle fatigue conditions (LCF – strain controlled).
Findings
At the same time, the present study analyses fatigue factors (ef, a, fSR, ed, ep, R, b) that define their inelastic relation between tension – strain and a prediction model on behavior of both reference and corroded steel rebar, in seismic loads conditions (LCF), is proposed.
Originality/value
Moreover, this study dealt with the synergy of corrosion factor and the existence of superficial ribs (ribbed and smoothed) in seismic behavior of steel bar S400 (BSt420). The S-N curves that are exported can be resulted in a first attempt of prediction of anti-seismic behavior on reinforced concrete structures with this the same steel class.
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This bibliography contains references to papers, conference proceedings, theses and books dealing with finite strip, finite prism and finite layer analysis of structures…
Abstract
This bibliography contains references to papers, conference proceedings, theses and books dealing with finite strip, finite prism and finite layer analysis of structures, materially and/or geometrically linear or non‐linear.
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Different approaches, originally developed for ambient conditions, exist in current codes and standards for incorporating the effect of moment–shear (M–V) interaction on the…
Abstract
Purpose
Different approaches, originally developed for ambient conditions, exist in current codes and standards for incorporating the effect of moment–shear (M–V) interaction on the plastic-carrying capacity of wide-flanged (WF) steel sections. There is a lack of experimental and theoretical studies that address this issue under fire conditions.
Design/methodology/approach
The current paper presents a numerical study investigating the effect of fire exposure on the plastic M–V capacity curves of doubly symmetrical, WF, hot-rolled steel sections. Validated high-fidelity finite element (FE) models constructed via ANSYS are used to study the effect M–V interaction on the plastic capacity of WF sections. Also, a simplified plastic sectional analysis, intended to be used by engineering practitioners, is proposed for generating the plastic M–V interaction curves.
Findings
The study shows that the fire-induced non-uniform heating of the section plates affects the shape of the plastic M–V interaction capacity curves. Comparison of different methods against FE results shows that the method specified in the Eurocode is very conservative at room-temperature, but it turns out to be barely sufficiently conservative under fire conditions.
Originality/value
It is well noted that lack of fire tests on the M–V interaction, including the stability of the plates of steel sections under fire, make it difficult to reach a definite assessment on the effect of M–V interaction on the bearing capacity of steel beams.
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Amit Dutta and Donald W. White
In the inelastic stability analysis of plated structures, incremental‐iterative finite element methods sometimes encounter prohibitive solution difficulties in the vicinity of…
Abstract
In the inelastic stability analysis of plated structures, incremental‐iterative finite element methods sometimes encounter prohibitive solution difficulties in the vicinity of sharp limit points, branch points and other regions of abrupt non‐linearity. Presents an analysis system that attempts to trace the non‐linear response associated with these types of problems at minor computational cost. Proposes a semi‐heuristic method for automatic load incrementation, termed the adaptive arc‐length procedure. This procedure is capable of detecting abrupt non‐linearities and reducing the increment size prior to encountering iterative convergence difficulties. The adaptive arc‐length method is also capable of increasing the increment size rapidly in regions of near linear response. This strategy, combined with consistent linearization to obtain the updated tangent stiffness matrix in all iterative steps, and with the use of a “minimum residual displacement” constraint on the iterations, is found to be effective in avoiding solution difficulties in many types of severe non‐linear problems. However, additional procedures are necessary to negotiate branch points within the solution path, as well as to ameliorate convergence difficulties in certain situations. Presents a special algorithm, termed the bifurcation processor, which is effective for solving many of these types of problems. Discusses several example solutions to illustrate the performance of the resulting analysis system.
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Miguel Abambres and Wai-Meng Quach
Although the actual residual stress distribution in any structural steel member can be only obtained by experimental measurements, it is known to be a difficult, tedious and…
Abstract
Purpose
Although the actual residual stress distribution in any structural steel member can be only obtained by experimental measurements, it is known to be a difficult, tedious and inefficient piece of work with limited accuracy. Thus, besides aiming at clarifying structural designers and researchers about the possible ways of modelling residual stresses when performing finite element analysis (FEA), the purpose of this paper is to provide an effective literature review of the longitudinal membrane residual stress analytical expressions for carbon steel non-heavy sections, covering a vast range of structural shapes (plates, I, H, L, T, cruciform, SHS, RHS and LSB) and fabrication processes (hot-rolling, welding and cold-forming).
Design/methodology/approach
This is a literature review.
Findings
Those residual stresses are those often required as input of numerical analyses, since the other types are approximately accounted for through the s-e curves of coupons cut from member walls.
Practical implications
One of the most challenging aspects in FEA aimed to simulate the real behaviour of steel members, is the modelling of residual stresses.
Originality/value
Besides aiming at clarifying structural designers and researchers about the possible ways of modelling residual stresses when performing FEA, this paper also provides an effective literature review of the longitudinal membrane residual stress analytical expressions for carbon steel non-heavy sections, covering a vast range of structural shapes (plates, I, H, L, T, cruciform, SHS, RHS and LSB) and fabrication processes (hot-rolling, welding and cold-forming).
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N. Venkataraman, S. Rangarajan, M.J. Matthewson, B. Harper, A. Safari, S.C. Danforth, G. Wu, N. Langrana, S. Guceri and A. Yardimci
Fused deposition of ceramics (FDC) is a solid freeform fabrication technique based on extrusion of highly loaded polymer systems. The process utilizes particle loaded…
Abstract
Fused deposition of ceramics (FDC) is a solid freeform fabrication technique based on extrusion of highly loaded polymer systems. The process utilizes particle loaded thermoplastic binder feedstock in the form of a filament. The filament acts as both the piston driving the extrusion and also the feedstock being deposited. Filaments can fail during FDC via buckling, when the extrusion pressure needed is higher than the critical buckling load that the filament can support. Compressive elastic modulus determines the load carrying ability of the filament and the viscosity determines the resistance to extrusion (or extrusion pressure). A methodology for characterizing the compressive mechanical properties of FDC filament feedstocks has been developed. It was found that feedstock materials with a ratio (E/ηa) greater than a critical value (3×105 to 5×105 s‐1) do not buckle during FDC while those with a ratio less than this range buckle.
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Norashidah Abd Rahman, Siti Amirah Azra Khairuddin, Mohd Faris Faudzi, Mohd Harith Imran Mohd Asri, Norwati Jamaluddin and Zainorizuan Mohd Jaini
Concrete-filled hollow section (CFHS) is widely used in steel construction. The combination of concrete and steel decreases buckling and deformation of steel. However, studies…
Abstract
Purpose
Concrete-filled hollow section (CFHS) is widely used in steel construction. The combination of concrete and steel decreases buckling and deformation of steel. However, studies reveal that using normal concrete increases the dead weight of a structure. Therefore, a lightweight concrete, such as foamed concrete (FC), is proposed to reduce the weight of the structure. The purpose of this study is to determine the strength of modified fibrous foamed CFHS (FCFHS).
Design/methodology/approach
Steel and polypropylene fibres were used with rice husk ash, and short column fibrous FCFHSs were tested under compression load. Greased and non-greased methods were adopted to determine bond strength and confining effect between steel and concrete.
Findings
Results indicate that the use of fibre in FCFHSs improves the strength of CFHS from 9% to 11%. The non-greased method confirms that an interaction exists between steel and concrete with a confinement coefficient of more than 2.0.
Originality/value
It can be shown that the modified fibrous foamed concrete can increase the strength of the concrete and can be used as concrete filled in steel construction industry.
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