Cross-section Of Members Research Articles

Static and Dynamic Stability of a Multi-stepped Timoshenko Column Including Self-weight

A simplified and easy to implement approach for the solution of the static and dynamic stability of a Timoshenko column with multiple partitions is derived in a classic and condensed manner. The proposed methodology includes a non-uniformly distributed axial load along the structural member which can represent the self-weight of columns, chimneys, tall buildings or the axial load on piles induced by downdrag forces. The proposed model includes the effects of shear deformations along the member and the second-order shear force induced by the applied axial load as the member deforms. The effects of the self-weight on the structural member stability are studied using the proposed approach and conclusions regarding the contribution of the self-weight and discrepancies by neglecting it are presented. Three comprehensive examples including columns with weakened sections, distributed axial loads arising from the self-weight, symmetrical tapered sections, and stepped cross sectional members are included to validate and show the applicability of the proposed formulation.

Effect of Non-Uniform Torsion on Elastostatics of a Frame of Hollow Rectangular Cross-Section

Abstract In this paper, results of numerical simulations and measurements are presented concerning the non-uniform torsion and bending of an angled members of hollow cross-section. In numerical simulation, our linear-elastic 3D Timoshenko warping beam finite element is used, which allows consideration of non-uniform torsion. The finite element is suitable for analysis of spatial structures consisting of beams with constant open and closed cross-sections. The effect of the secondary torsional moment and of the shear forces on the deformation is included in the local finite beam element stiffness matrix. The warping part of the first derivative of the twist angle due to bimoment is considered as an additional degree of freedom at the nodes of the finite elements. Standard beam, shell and solid finite elements are also used in the comparative stress and deformation simulations. Results of the numerical experiments are discussed, compared, and evaluated. Measurements are performed for confirmation of the calculated results.

Community Consensus: Herding Cats Along the Strategic Roadway

President's column Leadership via a Strategic Plan appropriate to the times The SPE International Board is an amazing group representing an even more amazing group—SPE membership. We really are passionate volunteers. Sometimes chairing this board can be daunting. Occasionally it is like herding cats. Overall, we mostly go in the same direction. At the March meeting in Ghana, the board concluded a winding journey on the road to a strategic plan. As our old 5-year plan had been largely accomplished, I was faced with leading the board into figuring out what was next to keep us moving forward. I’ll be honest, I was not looking forward to it. The good news is we did it. There is no bad news—I think we did it well. First, as a full board we brainstormed ideas then con-ducted a survey of a good cross section of members. We even used a facilitator to help with our focus. It went very well, and I am very proud of the final product. I want to thank Janeen Judah, 2017 SPE president, and Mark Rubin, SPE executive director, for starting the process and keeping the focus. I also want to thank the members who contributed, both through the formal process and by bending my ear during the past year or so. Some of the big changes were adding “sustainability” to our vision statement, and expressing five core values and four strategic priorities. We added a statement about professional pride. In this column, I’d like to talk about some of the big changes. Let’s start with sustainability. I know that your 2019 SPE President Sami Al-Nuaim will speak a lot about this (and I don’t want to steal his thunder), but I do want to express our desire to deliberately include sustainability into our vision statement. If we aren’t sustainable, we won’t exist for very long. It’s that simple. Defining sustainability in an extractive industry might be a little trickier, but I would suggest that sustainability for me is extracting the resource in the manner that will allow the longest possible life span and environmental stewardship.

Laser scan-based structural assessment of wrought iron bridges: Guinness Bridge, Ireland

This paper introduces a workflow to create the geometric documents for conducting the finite-element-based structural assessment of wrought iron bridges using laser scanning data as the input dataset. First, a methodology for identifying actual cross-sections of the bridge components based on a point cloud obtained from a terrestrial laser scanner (TLS) is presented. Next, a non-parametric regression kernel density estimation is employed to determine overall bridge dimensions to populate a computational model by projecting the position of the web and/or flange surface of the cross-section (appearing as local maximum peaks of a probability density shape). The process is demonstrated with respect to the previously undocumented Guinness Bridge in Dublin, Ireland, to determine the bridge’s behaviour. The successful generation of this model proves that TLS can surpass other common techniques (e.g. unmanned aerial vehicle-based images) for acquiring the bridge geometry necessary for reconstructing accurate member cross-sections and overall bridge dimensions, regarding the quantity and quality of the data points, and timing. The finite-element analysis showed that the bridge currently satisfies both strength and serviceability requirements under self-weight but would be unlikely to support a new slab and a modern pedestrian load level as per current code requirements for reopening the bridge.

Performance of rubberised reinforced concrete members under cyclic loading

This paper presents an experimental investigation into the cyclic behaviour of reinforced concrete members incorporating a significant proportion of recycled rubber particles as a replacement for mineral aggregates. Tests were carried out on thirteen large scale members of circular cross-section, with and without external confinement, and with different proportions of rubber content and axial loads. The specimens were subjected to inelastic lateral cyclic displacements and predefined levels of co-existing axial loading. After describing the testing arrangement and specimen details, the main results and observations are provided and discussed. The test results enable a direct comparative assessment of the key response characteristics of the specimens, with focus on stiffness properties and strength interaction, as well as ductility and energy dissipation. It is shown that rubberised reinforced concrete members can offer a good balance between bending capacity and ductility in comparison with conventional reinforced concrete members, particularly for low levels of axial loads. In the presence of relatively high axial loading and when a significant proportion of rubber content is used, external confinement such as through FRP sheets as employed in this study, can be adopted to recover the required capacity and to provide highly stable hysteretic response. The implications of the findings on the use of rubberised reinforced concrete members in practice, and procedures that can be used to determine the main design parameters, are also highlighted within the discussions.

Anatomical features of cross-sections of the genus Equisetum members

The anatomical structure of cross-sections of internodes of stems and branches of 9 species and 5 interspecific hybrids of the subgenus Equisetum and Hippochaete ( Equisetum , Equisetaceae) was studied: E. arvense L., E. fluviatile L., E. palustre L., E. pratense Ehrh., E. sylvaticum L., E. × mildeanum Rothm. ( E. pratense × E. sylvaticum ), E. × sergijevskianum CN Page et Gureeva ( E. pratense × E. palustre ), E. × lofotense Lubienski ( E. arvense × E. sylvaticum ), E. hyemale L., E. ramosissimum Desf., E. scirpoides Michx, E. variegatum Schleich. ex F. Weber et D. Mohr., E. × moorei Newman ( E. hyemale × E. ramosissimum ), E. × trachyodon (A. Braun) W. D. J. Koch ( E. hyemale × E. variegatum ). The species-specific anatomical features of the species of the subgenus Equisetum are as follows: the shape of the ridge on the cross-section (in profile) and the presence of silica spines, the size of the vallecular cavities, the position and size of the mechanical tissue under the ridges. For species from the subgenus Hippochaete , the number of ridges and the shape of the ridge on the cross-section, the outline of the mechanical tissue, the presence of siliceous tubercles are important. For all species, the diagnostic feature is the size and position of the mechanical tissue in the cut, as well as the position and number of layers of the endoderm. The size of the central cavity cannot be used as a diagnostic feature. In this case, it is better to use the relative dimensions of the vallecular cavities to the central cavity. The article gives detailed descriptions of cross-sections.

Numerical analysis of reinforced concrete structures with oriented steel fibers and re-bars

In this study, a new strength and stiffness numerical analysis approach of fiber reinforced concrete with oriented fibers and re-bars is proposed. The model is based on discrete lattice simulation that is obtained from standard tetrahedron mesh. Area of cross section of lattice members is obtained by homogenization of each tetrahedron finite element. A non-linear material constitutive model that takes into account fiber orientation, concrete damage and plasticity of re-bars is proposed. Re-bars are embedded in fiber concrete lattice by using a special joint elements that are consistent with re-bar’s surface pattern. The numerical model is validated by using four-point bending test results of high performance fiber concrete with oriented fibers. Moreover, the model showed a good agreement with re-bar pull-out test results for ultra-high performance concrete with oriented fibers. The proposed model is used to analyze a ribbed concrete panel with oriented fibers and best optimal fiber orientation for three-point bending is proposed.

Numerical calibration of mechanical behaviour of composite shell tunnel linings

Composite shell linings consist of primary and secondary sprayed concrete linings separated by a layer of spray-applied waterproofing membrane. In order to design such a lining configuration, a calibrated numerical simulation approach is needed and the impact of interface properties on the composite mechanical behaviour should be understood.A programme of laboratory tests was carried out on beam samples cut from composite shell test panels and subjected to four-point bending under short-term loading. A range of membrane thicknesses and substrate roughness were compared and composite mechanical behaviour quantification methods developed. The behaviour of composite beams was understood and the strain distribution across composite lining cross-section was identified.A numerical model by the finite difference method was then set up for the beams and verified against the test data. With interface stiffnesses obtained from previous element tests, the composite beam model is capable of predicting the strain distribution across the cross-section and real behaviour of composite beam members to within an acceptable level of accuracy taking into account variations arising from workmanship. Sensitivity studies were carried out to understand the impact of interface properties and membrane interface position on the degree of composite action.

Comments about the Seismic Behavior of “Inverted Y”- Braced Frames

Four configurations were analyzed for a ten storey “inverted Y-braced” frame with rigid and/or pined beam/column and diagonal/column connections. All considered frame configurations were sized for the forces produced by the same code seismic design force evaluated according to the in charge Romanian seismic design code. In case of two of the considered configurations, additional potentially plastic zones with reduced member cross-sections were provided along the girders and diagonals of the frame (in order to size clearly by design a global plastic failure mechanism for the “inverted Y-braced” frame). The behavior of each frame configuration during dynamic nonlinear analyses was observed. The steel consumption was estimated for each considered configuration.

Strength of Thin-Walled Lipped Channel Section Columns with Shell-Shaped Curved Grooves

Thin-walled member is structurally superior to a construction member. However, by reason of complexity in structure the stress and the deformation to yield the cross section are complicated. Specially, in case thin-walled members, such as thin-walled channel section columns, which are subjected to compressive force, these members produce the local buckling, distortional buckling and overall buckling. A number of experimental and theoretical investigations subjected to axial compressive force are generated for thin-walled channel section columns with triangle-shaped folded groove by Hancock [1] and with complex edge stiffeners and web stiffeners by Wang [2]. In case thin-walled channel section column with folded groove which is subjected to axial compressive force, it is cleared that the buckling mode shapes are ordinarily generated for local buckling mode shape of plate-panel composing cross section of member in short member aspect ratio and overall buckling mode shape as column and distortional buckling mode shape interacting between local buckling and overall buckling similarly normal thin-walled member. It is cleared analytically and experimentally that buckling strength and critical strength of thin-walled channel section column with folded groove can increase sharply in comparison with that of normal thin-walled member composing only plate-panel. In this paper a new cross section of shell-shaped curved groove [3] was proposed instead of the thin-walled lipped channel section column with triangle- and rectangle-shaped folded grooves used ordinarily, and therefore the comparison and the examination of buckling strength and buckling behavior were generated in the case of preparing triangle-shaped folded and shell-shaped curved grooves to web and flange of thin-walled channel section column. And then in order to investigate the buckling behavior on the thin-walled channel section column with folded and curved grooves, exact buckling strength and the buckling mode shapes are generated by using the transfer matrix method. The analytical local distortional and overall elastic buckling loads of thin-walled channel section column with folded and curved grooves can be obtained simultaneously by use of the transfer matrix method. Furthermore, a technique to estimate the buckling mode shapes of these members is also shown.

Dynamic stiffness formulations for harmonic response of infilled frames

In this paper, harmonic responses of infilled multi-storey frames are obtained by using a single variable shear deformation theory (SVSDT) and dynamic stiffness formulations. Two different planar frame models are used which are fully infilled and soft storey. The infill walls are modeled by using equivalent diagonal strut approach. Firstly, free vibration analyses of bare frame and infilled frames are performed. The calculated natural frequencies are tabulated with finite element solution results. Then, harmonic response curves (HRCs) of frame models are plotted for different infill wall thickness values. All of the results are presented comparatively with Timoshenko beam theory results to reveal the effectiveness of SVSDT which considers the parabolic shear stress distribution along the frame member cross-sections.

A one-dimensional model of 3-D structure for large deformation: a general higher-order rod theory

A higher-order one-dimensional model in a curvilinear cylindrical coordinate system and associated finite element model are presented. A general displacement field of the cross section of the rod or the structures in the polar coordinate system is assumed, and the associated governing equation of motion in the Lagrangian frame of reference is derived. Since the displacement field considered is very general, the theory is not limited to rods but can be used to analyze thick, solid, or hollow arbitrary cross section members or a shell structure whose axis can be given as a space curve. A nonlinear finite element model of the theory which can model large deformation is developed. Numerical examples are presented to illustrate the usefulness and accuracy of the model in analyzing shell structures (e.g., spiral duct), whose central axis is a space curve, subjected to point loads and internal or external pressure.

Buckling analysis of thin-walled members with open-branched cross section via semi-analytical finite strip transfer matrix method

Thin-walled members with open-branched cross section have been used in many modern engineering structures, and their buckling performance has been widely studied. In this paper, two transfer methods are developed to tackle the transfer problems at the junction of the open-branched cross-section of thin-walled members by using semi-analytical finite strip transfer matrix method (FS-TMM) which is a combined use of semi-analytical finite strip method (SA-FSM) and transfer matrix method (TMM) for the buckling analysis. Compared to traditional SA-FSM, this method has a smaller matrix and higher computational efficiency due to no global stiffness matrix generated. An asymmetric E-section member, a symmetric I-section member and a X-section member with loaded edges simply supported are analyzed by the derived formulation. All the results are compared with SA-FSM's or finite element method's results to prove the reliability and efficiency of this method.

From K Road to iTunes: Social and cultural changes in New Zealand recorded music communities

This article explores how recent technological changes have affected the social and cultural practices of New Zealand communities that are based on recorded music. It considers the shrinking number of brick-and-mortar record shops in the wider context of discussing how now widespread Internet usage has forever changed the music producer-distributor-consumer relationship, as well as the relationship audience members have with one another. The account tracks the history of the record retail space in 20th Century New Zealand, before drawing on conversations with 30 highly-engaged music consumers in order to explore the relevance of the record shops that remain today. Participants also discuss the impact Internet access has had on New Zealand-based music aficionados. The central theme that emerges during these conversations is that though ‘something’ is lost with increasingly less physical community spaces to congregate, the Internet provides a potentially more inclusive and expansive platform for a greater cross-section of audience members to feel involved.

Testing and numerical analysis on cold-formed steel shear walls using corrugated steel sheathing

Cold-formed steel framed shear wall sheathed with corrugated steel sheets is a promising shear wall system for low- and mid-rise constructions at high wind and seismic zones due to its advantages of non-combustibility, high shear strength, and high shear stiffness. Monotonic and cyclic tests on full-scale wall assemblies using corrugated steel sheathing was conducted. To investigate the effect of vertical/gravity loading, shear wall specimens were tested under two different loading conditions: lateral loading, and a combined lateral and vertical/gravity loading. The test results are presented and discussed in this paper. Besides, finite element model of the proposed shear wall was created in Abaqus software. The validity of the numerical model was verified based on the test results. A series of parametric analysis were conducted, including the thickness of framing members, the cross section of stud members, yield strength of the frame members, stud spacing, and the influence of gravity loads. The detailed modeling information, relevant parametric analysis and recommendations for practical application of this type of shear resisting system are also presented.

Community service for misdemeanours in Accra: Preferences of offenders, victims, judiciary, and community members

Taking religiosity into account, the study explored preferences for community service sentencing by victims, offenders, judiciary, and community members from Accra, Ghana. One hundred and ninety respondents were sampled (females = 38.42%, offenders = 5.26%, victims = 58.95%, law enforcement = 10.52%, members of the Judiciary = 4.74%, and general community members = 65.26%). They responded to the Attitude Towards Community Service Questionnaire, and the data were analysed utilising ANOVA between group difference tests. Offenders expressed a higher preference for community sentencing than victims and members of the judiciary. Religion aligned participants supported community sentencing. Community sentencing seems a preferred sentencing option by a cross section of Ghanaian community members for adult non-violent offenders.

Progressive failure analysis of thin-walled Fibre Metal Laminate columns subjected to axial compression

The subject of the paper is the progressive failure analysis (PFA) of thin-walled Z-shape cross section members subjected to axial compression. This study concerns angle-ply multi-layered Fibre Metal Laminates (FMLs) which consist of alternating thin layers of aluminium and glass fibre-reinforced unidirectional prepreg. Laboratory damage tests were performed by the static testing unit that provided displacement control loading. Experimental results were compared with FEA wherein based on the profile's nonlinear stability investigations the failure analysis was performed. Nonlinear FE simulation combined with available progressive failure mechanics allowed to predict the initiation and propagation of the multi-failure modes within composite material. Hashin failure criterion was used to monitor the initiation of damage, whereas material degradation method (MPDG) was applied in FRP layer to define the damage evolution law. Damage variables were specified according to FEM modelling procedures in order to control material stiffness reduction after damage initiation. For aluminium layers the J2 plasticity model was employed. Progressive failure assessment by FEM allowed to estimate the post-buckling equilibrium paths and damage modes with particular regions of laminate's fracture that were found to be in a good agreement with experimental evidences.

Optimal design of pitched roof frames with tapered members using ECBO algorithm

Pitched roof frames are widely used in construction of the industrial buildings, gyms, schools and colleges, fire stations, storages, hangars and many other low rise structures. The weight and shape of the gable frames with tapered members, as a familiar group of the pitched roof frames, are highly dependent on the properties of the member cross-sectional. In this work Enhanced Colliding Bodies Optimization (ECBO) is utilized for optimal design of three gable frames with tapered members. In order to optimize the frames, the design is performed using the AISC specifications for stress, displacement and stability constraints. The design constraints and weight of the gable frames are computed from the cross-section of members. These optimum weights are obtained using aforementioned optimization algorithms considering the cross-sections of the members and design constraints as optimization variables and constraints, respectively. A comparative study of the PSO and CBO with ECBO is also performed to illustrate the importance of the enhancement of the utilized optimization algorithm.

Steel Lattice Tower Under Ultimate Load – Chosen Joint Analysis

Abstract The main objective of the presented paper is to discuss chosen lattice tower joint behavior under structure ultimate load. Joint numerical modelling considerations are enriched with comparison to the full-scale tower pushover test results. Two independent load cases were examined: 1) where the L-sections (diagonal bracings) are loaded by the axial force only and that forces are applied in the center of the member cross section, 2) where the L-sections are loaded by the axial force and the bending moment that reproduce the effect of the eccentric connection to the gusset plates by the one leg of the angle section is added. Differences in equivalent stresses state for two independent design situations allow for conclusion that additional bending moments should be taken into account, especially for thin-walled members.

Experiment and Design Method on Cold-Formed Thin-Walled Steel Lipped Channel Columns with Slotted Web Holes Under Axial Compression

Background: Cold-formed steel structural sections used in the walls of residential buildings and agricultural facilities are commonly C-shaped sections with web holes. These holes located in the web of sections can alter the elastic stiffness and the ultimate strength of a structural member. The objective of this paper is to study the buckling mode and load-carrying capacity of cold-formed thin-walled steel column with slotted web holes. Methods: Compression tests were conducted on 26 intermediate length columns with and without holes. The tested compressive members included four different kinds of holes. For each specimen, a shell finite element Eigen-buckling analysis and nonlinear analysis were also conducted. The influence of the slotted web hole on local and distortional buckling response had also been studied. The comparison on ultimate strength between test results and calculated results using Chinese cold-formed steel specification GB50018-2002, North American cold-formed steel specification AISI S100-2016, and nonlinear Finite Element method was made. Result: Test results showed that the distortional buckling occurred for intermediate columns with slotted holes and the ultimate strength of columns with holes was less than that of columns without holes. The ultimate strength of columns decreased with the increase in transverse width of hole in the cross-section of member. The Finite element analysis results showed that the web holes could influence on the elastic buckling stress of columns. The shell finite element could be used to model the buckling modes and analysis the ultimate strength of members with slotted web holes. The calculated ultimate strength shows that results predicted with AISI S100-2016 and analyzed using finite element method are close to test results. The calculated results using Chinese code are higher than the test results because Chinese code has no provision to calculate the ultimate strength of members with slotted web holes. Conclusion: The calculated method for cold-formed thin-walled steel columns with slotted web holes are proposed based on effective width method in Chinese code. The results calculated using the proposed method show good agreement with test results and can be used in engineering design for some specific cold-formed steel columns with slotted web holes studied in this paper.