Aluminum Sections Research Articles

Enhancing the punching performance of two-way RC flat slabs using different configurations of embedded aluminum sections: Experimental program and numerical analysis

Punching occurs in flat slabs around the column as a result of increased column loads, inadequate steel reinforcement, and weak concrete strength. The goal of the current research is to improve the punching resistance of two-way reinforced concrete (RC) flat slabs using internal strengthening with aluminum sections. An experimental program consisting of ten RC flat slabs was prepared and tested to show the effects of three different strengthening configurations (horizontal and vertical, diagonal, or hybrid system consisting of horizontal, vertical, and diagonal sections) on the structural characteristics of RC flat slabs. Also, the effect of the thickness of the strengthening aluminum sections (1.0, 1.5, and 2.0 mm) on the ultimate load, load-mid span deflection responses, stiffness, and absorbed energy of RC flat slabs was investigated. According to the results, the three slabs in the group with the vertical and horizontal aluminum sections had the highest improvements in ultimate loads among all tested slabs of 50.9%, 57.1%, and 68.9% for aluminum thicknesses of 1.0, 1.5, and 2.0 mm, respectively, compared to the control slab. Moreover, a three-dimensional (3D) non-linear finite element model (FEM) was constructed using ABAQUS software. The proposed model was validated using the experimental records. Then, the validated model was used to investigate the effects of the interspacing between the aluminum sections on the ultimate load, load-deflection responses, stiffness, and absorbed energy of two-way RC flat slabs.

Statics and stability of diagonalless beams of particular kind – preliminary studies

Attractive large-scale glazing is currently an architectural trend. However, achieving adequate stiffness for larger glazing spans requires the use of complex cross-sections, generally aluminium sections of considerable height. Members with openwork webs are sometimes used in order to achieve increased load-bearing capacity and stiffness with reduced weight. The disadvantage is that this solution takes up a lot of space inside the building. A recently patented diagonalless member attempts to solve the above-mentioned problems. The member is fully demountable and allows glass units to be installed in the space between the chords. It consists of two chords spaced apart by metal sleeves with bolts passed through them. In this study, preliminary qualitative experimental tests were carried out to determine the behaviour of the member under load and to identify zones sensitive to local deformation. On this basis, numerical models (bar and 3D solid models, including contact interactions) were created and tested. Subsequently, the optimum sleeve spacing was determined, the effect of rotational and translational stiffness reduction at the nodes was investigated, and stress concentration zones and forms of stability loss were identified. A new form of local loss of stability of the chord facewall was identified, the so-called sliding push effect of the chord walls on the sleeve (within the larger openings). This is a completely different type of chord facewall failure from that found in known tubular welded joints. The research programme focused on identifying the phenomena occurring in the new member in order to provide a basis for further, more advanced analyses.

Research on lateral buckling of eccentrically compressed H-shaped section aluminum alloy perforated members

Aluminum alloy members are widely used in various engineering fields because of the light weight and corrosion resistance. However, the existing research on the stability of the aluminum alloy beam-column with web openings is insufficient. This study carried out the eccentrically compressed tests for 60 H-shaped section aluminum alloy perforated members, taking the opening number, opening diameter, slenderness ratio, and eccentricity distance around major axis as main variables. The tested specimens showed obvious lateral buckling. The effects of web openings on buckling mode, stability bearing capacity, longitudinal deformation, lateral deformation, and strain development of the member are studied. The influence of each variable on the mechanical properties is studied, which provides the basis for design of the structure members. Several main parameters are analyzed in depth using verified finite element model. Based on the results of test and FEA, the design method for lateral stability bearing capacity of H-shaped section aluminum alloy perforated members is proposed with reference to existing specifications.

Study on stability of H-type section aluminum alloy perforated members under axial compression and eccentric compression around weak axis

Aluminum alloy components have the advantages of light weight, high strength, favorable machinability, and good acid corrosion resistance, which can greatly reduce maintenance costs and easy to make the structures with beautiful appearance. Based on the shortcomings of existing research fields, the stability of H-type section 6082-T6 aluminum alloy perforated members under axial compression and eccentric compression around weak axis is studied by combining experimental and numerical simulation methods in this paper. The test results of aluminum alloy members under axial compression and aluminum alloy members under eccentric compression around weak axis with different web opening numbers, opening diameters, slenderness ratios and eccentric distances are analyzed. The verified finite element model is used to carry out the extensive parameter analysis focusing on the key variables. Based on the test and numerical simulation results of the stability bearing capacity of 134 members, the design methods for H-type section aluminum alloy perforated members under axial compression and eccentric compression are proposed and evaluated by reference to the existing specification.

Effect of beam oscillation on weld formation, microstructure and mechanical properties in vacuum laser beam welding of thick section 5083 aluminum alloy

Beam oscillation in the laser welding process has demonstrated numerous advantages in suppressing spatters, eliminating pores, and reducing gap sensitivity, particularly for joining thin plates. This study presents the welding of thick section aluminum alloy using laser beam oscillation in a vacuum environment. During vacuum laser welding, the effect of beam oscillation variables, which include oscillating path, amplitude, and frequency, on weld seam morphology, microstructures, and mechanical properties was symmetrically evaluated. The findings indicate that in a vacuum environment, beam oscillation with a small amplitude can optimize the contour of the weld sidewall and increase the penetration depth, which is different from that observed in an atmospheric environment, where the melting penetration depth decreases with increasing oscillating amplitude. The deep penetration weld seam in a vacuum environment can achieve an extremely small size of 19 ∼ 30 µm. The addition of small oscillations causes a slight increase of the average grain size. The stirring effect of beam oscillation was weakened because of the minimized weld pool size under vacuum. This increased grain size is mainly attributed to the changes in the size of the molten pool caused by the oscillation cause changes in solidification parameters which accelerate grain growth. However, increasing the oscillation frequency can greatly increase the strength of the stirring effect and the refinement ability of small-sized grains. On further increasing the oscillation frequency to 200 Hz, the grown grains are refined. The results showed the tensile strength of the vacuum laser weld joints with and without beam oscillation can achieved a value of about 90 % of the base metal, which is superior to the strength of the joints welded by atmospheric pressure laser welding and can meet the vast majority of welding needs.

Web crippling behaviour and design of aluminium SupaCee sections

AbstractSupaCee sections are addressed as one of the innovative section profiles which was introduced to the Cold‐Formed Steel (CFS) industry in the past decade. Longitudinal stiffeners and return lips are the unique features which ensured the better structural performance in terms of bending and shear for CFS sections. However, web crippling performance of CFS SupaCee section was the critical aspect to employ them in the industry as the concentrated loads could induce web crippling failures. Hence, there is a necessity to address web crippling performance of any innovative profiles to utilize them in appropriate locations. On that note, aluminum sections are now emerging in the industry as load bearing profiles considering their lightweight nature, corrosion resistance, ease of fabrication and high specific strength. Aluminium sections are considered as a replacement for CFS sections for modular constructions where the necessity of light weight is higher considering the transport costs and fabrication costs. However, web crippling performance of aluminum sections has to be analyzed to ensure the utilization in modular constructions. Hence, a superior section among available sections in terms of structural performances, aluminium SupaCee section, was considered for this study. Accordingly, a comprehensive numerical study was conducted considering various parameters such as section depth, thickness, bearing length and yield strength, after the successful validation process of the numerical models with the experimental scenarios of End‐Two‐Flange (ETF) loading condition. Ultimately, the results were compared with key parameters and suggestions and recommendations were stated for the utilization aluminum SupaCee sections in the industry.

Design of aluminium Sigma sections for web crippling behaviour under Interior Two Flange (ITF) load case

AbstractAluminium sections have been emerged in the industry due to the advantages such as light weight, resistance to corrosion, recyclability, and flexibility. While the construction industry is moving towards to modular construction trend, aluminium sections are considered as a vital key to achieve the desirable outputs of modular industry. Modular industry needs high performing structural elements as well as light weight elements to reduce the overall weight of the modules which directly affects the transport cost, flexibility of the modular connections, construction duration, capacity of the equipment or machineries and required numbers of construction workers for assemble. Hence, the requirement of light weight elements is evident, and the aluminium sections have been considered to replace the conventional sections. However, the structural performance of aluminium sections has to be analysed to check the appropriateness of utilization though it is reasonable. Hence, aluminium sigma sections were selected in this study to check their performance in the web crippling scenario under Interior‐Two‐Flange (ITF) loading case. Sigma sections were opted based on the merits including high torsional rigidity and resistance towards local and distortional buckling. Appropriate numerical approach was selected, and the procedure was validated with experimental results. Accordingly, comprehensive numerical investigation was carried out by including different parameters such as depth, thickness, yield, and ultimate strength and bearing length. Subsequently, the results were compared with all critical parameters and the results were provided. Suggestions and recommendations were stated to utilise the aluminium sigma sections in the industry.

Progress in measurements of fission cross sections and total cross sections at CSNS Back-n white neutron source

The neutron-induced cross sections are of great significance for the design of nuclear devices and advanced reactors for the nuclear energy production. At CSNS Back-n white neutron source, new measurements of the fission cross sections and total cross sections are performed with two sets of Day-one spectrometers based on the multi-cell fast fission ionization chamber (FIC). The neutron-induced 236,238U fission cross sections relative to 235U from the fission threshold energy to 200 MeV were measured by using the TOF method and the Fast Ionization Chamber Spectrometer for Fission Cross Section Measurement (FIXM) in the single/double bunch mode of Back-n. The experimental uncertainties are analyzed in detail, and the results from the two modes are consistent. The measured 236,238U/235U fission cross section ratios are compared with previous experiments and evaluations. The 236,238U(n,f) cross sections are obtained based on the standard 235U fission cross section. The neutron total cross sections of carbon and aluminum in the energy region from 1 eV to 20 MeV have been measured by using the TOF method and transmission method based on the Neutron Total Cross Section Spectrometer (NTOX) in the double bunch mode. The total cross section results after unfolding are in good agreement with the previous measurements as well as the broadening of the ENDF/B-Ⅷ.0 evaluation with Gaussian function within the experimental uncertainty. The present results provide the experimental data for further measurements, relevant evaluations and the design of nuclear system.

Behavior of hollow self-compacted concrete beams reinforced with aluminum sections

This paper presents a study on improving the flexural performance of self-compacting hollow concrete beams with embedded aluminum sections, both experimentally and numerically. The experimental program involved testing three specimens to illustrate the impact of the bare and aluminum-reinforced voids on the mechanical properties of the hollow beams relative to the solid reference beam. A three-dimensional (3D) non-linear finite element model (FEM) was initially developed using ABAQUS software and validated against experimental results. The validated model examined the effects of void area (16–49% of the beam cross-section), void configuration (square or circular), longitudinal tensile reinforcement ratio (0.41–1.19%), and shear reinforcement ratio (0–0.56%) on the failure patterns and load–displacement relationships of hollow reinforced concrete (RC) beams with or without reinforced internal aluminum sections. Results showed that the embedded aluminum reinforcement promoted a more uniform distribution of flexural cracks along the effective length of the hollow RC beams and delayed the formation of shear cracks compared to the bare specimens. Furthermore, the embedded aluminum reinforcement effectively restored the ultimate capacity of the hollow beams with a void area ranging from 16 to 36% of the beam cross-section. Despite having the same area, the ultimate load-carrying capacity of both bare and reinforced beams featuring circular voids was higher than those with square voids.

Application of American Aluminum Specification in Design of Cold-Rolled Aluminum Alloy Channel Columns

Cold-rolled aluminum sections are new products that are available in the market with two typical sections of channel and Zed sections. These sections in the form of thin-walled sections become sensitive to buckling instabilities, leading to different behaviors in comparison with those of traditional extruded aluminum sections. The current aluminum design standards were regulated on the basis of research studies on extruded aluminum sections, and their accuracies in the design of cold-rolled aluminum members have been not reported. Based on collected experimental and numerical strengths of cold-rolled aluminum channel columns, the paper will compare these collected data with the strengths predicted by American Aluminum Specification. The comparisons are the bases to provide recommendations for the application of American Aluminum Specification in the design of cold-rolled aluminum channel columns. This specification was found to give conservative predictions for global buckling failure modes and provide un-conservative predictions for local-global interaction buckling failure modes in the design of aluminum alloy channel columns.

Numerical Investigation of Sectional Buckling Behaviors of Cold-Rolled Aluminium Alloy Channel Columns

Cold-rolled aluminium sections can be seen as the new products and are manufactured by using the existing rolling system for cold-formed steel sections. These new sections have illustrated their advantages in comparison with the extruded aluminium sections. The buckling behaviors of cold-rolled aluminium sections are different from those of the extruded ones; and their behaviors have been illustrated to be significant impacts by geometric imperfections due to unavoidable reasons in manufacturing, transportation and assembly. The paper, therefore, investigates the sectional buckling behaviors of cold-rolled aluminium alloy channel columns with the consideration of the geometric imperfections in the analysis. The imperfection amplitudes used for the investigation are randomly selected based on the collected data from previous research studies. The investigated results are the base for the analysis of sectional buckling behaviors of cold-rolled aluminium alloy channel columns, and for the determination of detrimental strengths that can be used for further studies.

Global Buckling Experiments of Cold-rolled Aluminium Alloy Downturn Lip Channel Beams

The paper is aimed to describe an experimental program of cold-rolled aluminium alloy downturn lip channel beams undergoing global buckling. Cold-rolled aluminium sections can be seen as new products of BlueScope Permalite, and the downturn lip channel section is in the form of the channel section with a modification of the bottom lip direction. A series of four tests with two lengths were carried out at The University of Sydney. The experiments were driven by a dual-actuator loading system to ensure the applied load was in the upward direction through the shear centre of the investigated section specimens while testing. Global buckling failures were seen in all specimen tests. The obtained test results will be the base for the calibration of a finite element model and the proposal of new design guidelines for these section beams subjected to global buckling modes in further studies.

Impacts of geometric imperfections on global buckling behaviors of cold-rolled aluminium alloy channel beams

Aluminium alloy structures have been seen as relatively new structures and have illustrated their advantages based on their properties of excellent corrosion resistance and lightweight. Aluminium alloy members can be manufactured by two methods including extrusion and cold-forming. While extrusion is seen as the traditional method worldwide, cold-rolling is recently applied to successfully produce cold-rolled aluminium sections with advantages in cost-effectiveness compared to extruded sections. significant geometric imperfections are found to be contained in these aluminium sections, which affects the strengths and behaviors of these section members. The consideration of geometric imperfections in the buckling analyses allows for determining the detrimental cases of buckling behaviors under load actions; that can be used for the proposal in design for further studies. The paper, therefore, studies the impacts of geometric imperfections on the global strengths and behaviors of such aluminium alloy beams; this will be the base for the development of parametric studies to obtain numerical data for design proposals. The imperfection values for the investigations are taken as random samples generated based on the collected imperfection data in previous studies. Also, a coefficient is proposed in reliability analysis to consider the influences of global imperfections on the global buckling moments of cold-rolled aluminium channel beams using the probability-based load and resistance factor design (LRFD) method as regulated in the American Aluminum Specification.

Elastic Global Buckling Moments of Cold-rolled Aluminium Alloy Asymmetric Section Beams

Cold-rolled aluminium sections are the new products introduced by BlueScope Permalite. These products have illustrated their cost-effectiveness in comparison with the traditional extruded aluminium alloy sections, which has attracted the attention of users and researchers. Research projects on cold-rolled aluminium alloy structures have been carried out to investigate the strengths and behaviors of such members that are the base for the development of the design guidelines for this new structural type. Cold-rolled aluminum alloy sections in the form of thin-walled sections are sensitive to instability. The design guidelines, therefore, have been proposed on the basis of the design of cold-formed steel structures with the development of the Direct Strength Method. The buckling analyses are conducted to determine the elastic buckling load, which is a compulsory step for the application of this method. The buckling analyses for symmetrical sections have been thoroughly investigated whereas these analyses for asymmetric sections are not clearly regulated in the design standards. Based on the experimental and numerical investigations on cold-rolled aluminium asymmetric section beams in a research project conducted at the University of Sydney, the paper will investigate the elastic global buckling moments of these asymmetric beams by using different methods including numerical, experimental and theoretical methods. The investigated results are subsequently discussed to figure out the procedure for the determination of elastic global buckling moments of the investigated cold-rolled aluminium alloy asymmetric section beams.

Experimental and Numerical Investigation of Aluminum Beams: Flexural Behavior Section Shape Effect

Advanced technology and other aspects of life aim to use the available and efficient materials. Due to their high strength-to-weight ratio and durability, aluminum alloys are used in a variety of structural engineering applications. This paper describes the experimental and numerical flexural behavior investigation of the aluminum beams. The main variables considered in the study are related to section shape, which are the shape configuration, depth, and thickness of the aluminum section. The finite element three dimensional models are used to analyze the tested beams in order to check the ability of the models to predict the overall behavior and to obtain more information about the stresses and strains that developed. The results show that the larger the value of the section shape factor, the fiber is still in the elastic range, and the smaller the plastic deformation of the beam. And the web plates slenderness ratio has a significant influence on the load-deflection relationship because of local deformation as well as the plastic deformation of box beams is relatively smaller than that of the I-section beam. The constraint of the flange for box beams is greater than that for I-section beams. Besides, the adopted nonlinear numerical modeling gives acceptable agreement with the experimental results besides the load-deflection responses, the ultimate strength convergence ratios varied between 1.1-0.93.

EVALUATION OF CAPACITIES OF COLD-ROLLED ALUMINIUM ALLOY COLUMNS ACCORDING TO THE AUSTRALIAN/NEW ZEALAND ALUMINIUM STANDARD

The cold-rolled aluminium sections are the new products made by utilising the existing cold-rolling system for cold-formed steel sections with two typical sections of channel and Zed sections. These new products have been demonstrated to save time and cost in manufacturing. The design of the cold-rolled aluminium members has been not regulated by any standards in the world. Research studies on behaviors and strengths of these members, therefore, have been carried out and original results on cold-rolled aluminium channel columns undergoing global buckling have been obtained. These studies were conducted in Australia. Therefore, the paper will collect these study results on cold-rolled aluminium channel columns, and these results are subsequently compared with the capacities from the Australian Aluminium Standard. The comparisons are carried out by using the reliability analysis as regulated in the American Aluminum Specification; this will be the base to evaluate the Australian/New Zealand Aluminium Standard in the design of cold-rolled aluminium alloy channel columns undergoing global buckling. It is found that the Australian standard provides un-conservative predictions for cold-rolled aluminium channel columns.

Template for Evaluating Cradle-to-Site Environmental Life Cycle Impacts of Buildings in India.

A massive amount of building construction is expected in economically developing nations such as India over the next few years. The first step in ensuring that the new construction takes place in a sustainable manner is the knowledge about the building's impact on multiple environmental domains. Life cycle assessment (LCA) is a promising tool for this, but its application in the Indian construction sector is hampered by a lack of access to detailed inventory data on amounts of all building materials used and the per unit environmental footprints of individual materials (characterization factors). Here, we overcome these limitations by proposing a novel approach that connects the building bill of quantity data with publicly available analysis of rate documents to obtain the detailed material inventory. The approach then combines the material inventory data with the newly available India-specific environmental footprint database of construction materials to calculate the impacts of a building during its different life cycle stages (cradle to site). We demonstrate the new approach through a case study of a residential building within a hospital in North-East India and quantify its environmental footprint on six domains of the environment: energy use, global warming, ozone depletion, acidification, eutrophication, and photochemical oxidant formation potential. Results show that out of 78 materials used, bricks, aluminum sections, steel bars, and cement are the major contributors to the building's total environmental impact. The material manufacturing stage is the hotspot in the building's life cycle. Our approach can act as a template for conducting "cradle-to-site" LCA of buildings for which BOQ data becomes available in India and other countries in the future.

Local buckling of aluminium channels under uniform compression: Theoretical analysis and experimental tests

The aim of the work is the evaluation of the ultimate behaviour of aluminium channel sections subjected to local buckling under uniform compression. In particular, two different approaches are presented to predict the inelastic response of aluminium members: the Deformation Theory of Plasticity (DTP) and the Effective Thickness Method (ETM). The first one represents a theoretical procedure applied according to elastic–plastic stability theory of a single plate and considering restraining effects of adjacent plate elements. The Effective Thickness Method (ETM) is a simplified approach currently adopted by Eurocode 9 to estimate the ultimate resistance of aluminium sections taking into account the local buckling effects. In this paper, an extension of this approach is provided by introducing the mechanical non-linearity of material and the influence of section plates constraints.Finally, the accuracy of these procedures is demonstrated by comparing the ultimate compressive resistance derived by theoretical approaches with the values of the ultimate loads provided by the stub column tests performed at the University of Salerno.

Concrete-filled and bare 6082-T6 aluminium alloy tubes under in-plane bending: Experiments, finite element analysis and design recommendations

The application of aluminium alloys in structural engineering is growing owing to their high strength-to-weight ratio, aesthetic appearance and excellent resistance to corrosion. However, the low modulus of elasticity of aluminium poses adverse effects on the flexural response of structural members made of aluminium alloys. In case of tubular members, the performance can be improved with the addition of concrete infill. Research on the flexural response of concrete-filled aluminium alloy tubes is still minimal. This study presents experimental and numerical investigations on the behaviour of concrete-filled and bare 6082-T6 aluminium alloy tubular members under in-plane bending. In total 20 beams, including 10 concrete-filled aluminium alloy tubular (CFAT) and 10 bare aluminium alloy tubular (BAT) specimens, were tested. The specimens comprised of square and rectangular hollow sections and were filled with 25 MPa nominal cylinder compressive strength concrete. The experimental results are reported in terms of failure mode, flexural strength, flexural stiffness, ductility and bending moment versus mid-span deflection curve. Compared to the BAT specimens, the counterpart CFAT specimens have shown remarkably improved flexural strength, stiffness and ductility due to the concrete infill and the improvement is more pronounced for the specimens with thinner sections. Finite element models of BAT and CFAT beams were developed by taking into account the nonlinearities in geometry and material and validated against the experimental data. A parametric study considering a broad range of cross-sections and different concrete grades was conducted based on the validated models. The FE results have shown that the flexural strength of the BAT and CFAT members increases with the increase of cross-sectional aspect ratio, wall thickness and concrete grade. The results obtained from experiments and numerical analysis for BAT members were used to assess the flexural capacity predictions and the applicability of the slenderness limits provided in the European standards. It was demonstrated that the slenderness limits provided by Eurocode 9 are conservative for Class A aluminium sections. Hence, revised Class 1, Class 2 and Class 3 limits are proposed which appear to be better applicable to Class A aluminium alloys. In the absence of design specifications for CFAT flexural members, the design rules for concrete-filled steel tubular flexural members provided by Eurocode 4 were adopted and the material properties of steel were replaced with those of aluminium alloy. It was shown that the proposed design methodology is suitable for the design of CFAT flexural members. Moreover, a slenderness limit for compact sections of CFAT flexural members is proposed based on Eurocode 4 framework.

Improving local stability of aluminium profile with low-modulus stiffeners: Experimental and numerical web buckling analysis

Facades of modern buildings are the frequent objects of application of aluminium profiles. Reduction of the self-weight governs the development of those structures—a decrease of the web thickness and an increase of the profile height ensure the required flexural resistance of the building components. However, such an optimisation process makes these structural elements vulnerable to web crippling. The findings reported in the literature linked the solution of the buckling problem to the application of low-modulus filler material to stabilise the web’s deformations and increase the load-bearing capacity and the deformation energy absorption of thin-walled composite elements. This study experimentally illustrates the above solution, developing an efficient hybrid cross-section. A hollow section aluminium profile (mullion) available on the market was the subject of the three-point bending and compression tests. Low-modulus polymer stiffeners produced using a 3D printing technique strengthened the composite samples developed in this study. The infill density of the printed polymer was the variable of the research. A 10% printing density was the minimum value used in the tests. The adhesively bonded stiffeners, even of the minimum infill density, doubled the flexural resistance of the profiles. A local buckling caused the failure of the reference specimens, having no internal infill. On the contrary, the aluminium breakage resulting from the strengthened samples’ tests indicates an efficient use of materials. A simplified numerical linear buckling analysis helps to explain the stiffeners’ effect.