Member Section Research Articles

Capacity of unstiffened multi-planar tubular KK-gap joints under anti-symmetric loading

This research presents a mathematical formula for calculating the capacity of anti-symmetric loaded multi-planar KK gap joints. The study was conducted using a well-calibrated and validated finite-element model, with 172 records generated for the parametric study using different geometries, member sections, and material properties. The results of the parametric study were analyzed using the GRG solving technique to develop a final predictive model. The developed model can predict actual joint capacity as a 3D joint, rather than approximating it as a 2D joint as in previous literature. It consists of two equations based on the ratio of the gap (gt/gl) with a transition point of (gt/gl) ≈ 0.9, which distinguishes between two different modes of load-transfer mechanisms: membrane action and direct shear action. The formula results were compared with experimental test results and showed an average accuracy of 91.2%.

Experimental investigation of flexural buckling behaviour of self-compacting lightweight concrete-filled cold-formed built-up box section (CFBBS) columns

This paper presents an experimental investigation of the flexural buckling behaviour and resistance of innovative self-compacting lightweight concrete (LWSCC)-filled cold-formed built-up box section (CFBBS) columns. A series of sixteen LWSCC-filled CFBBS columns and four reference hollow columns formed by two nested asymmetric lipped channel sections using breakstem rivets at flanges with various member relative slendernesses ratios, concrete strengths and section sizes were tested under pin-ended boundary conditions. Material tests and initial global geometry imperfection measurements were carried out and reported in present study. The failure modes and deformation developments, lateral deflection distribution along the column specimens, flexural buckling resistance and load-end shortening relationship of the specimens were scrutinised and discussed concerning the effect of parameters and the associated coupling effects. Furthermore, a comprehensive strain analysis was conducted and reported based on the longitudinal and lateral strain developments at both compression and tension zones under flexure; it was found that the composite action abated as the member length increased. Finally, as there is no existing design codes for LWSCC-filled CFBBS columns, the experimental results were used to evaluate the applicability of relevant international codified provisions, including Eurocode (EC4), Australia/New Zealand Standard (AS/NZS 2327) and America Specification (AISC 360-16). It was found that AS/NZS 2327 yielded the most accurate and moderately scattered predictions while the predictions from EC4 were found to be the most scattered but with reasonable accuracy and those from AISC 360-16 were overly conservative, albeit the least scattered among these design codes.

Study on Flexural Performance of Aluminum Alloy Gusset Joints Subjected to Bending Moment and Shear Force

Aluminum alloy gusset (AAG) joints are widely applied in space reticulated shell structures. To investigate the flexural performance of AAG joints under the combined action of shear force and in-plane and out-of-plane bending moments, this analysis was developed by means of finite element (FE) models implemented in the non-linear code ABAQUS, and the accuracy of the FE simulation results based on the existing AAG joint test results was verified. The FE simulation results effectively described the mechanical properties of the AAG joints, including the failure mode, deformation process and bending moment-rotation curves. Furthermore, a parametric study was conducted by varying the height of the member section, the number of bolts, the radius of the joint plate, the thickness of the joint plate, the bolt preload force, and the ratio of in-plane to out-of-plane bending moments. It was found that these parameters had different effects on the bending behavior of the AAG joints.

Size and layout optimum design of frames with steel plate shear walls by metaheuristic optimization algorithms

Optimization of a structure refers to a design procedure that results in the most economical structure in terms of materials and sizing of sections. In structures with steel plate shear walls, finding the best layout of the walls in a frame is also of priority in designing a structure with the minimum weight. Finding the least weight of a structure while all design provisions according to codes and standards are satisfied is a challenging task that is hard to perform with the existing design methods. Metaheuristic optimization algorithms are robust computational tools used for solving complex problems, which are used widely in many engineering fields, especially structural engineering. This paper presents a viable approach for the optimal design of frames with steel plate shear walls by applying modified dolphin echolocation (DE) and Bat optimization algorithms. The goal is to minimize the structure's weight, defined as the algorithm's objective function. To this end, a section list of beams and columns is predefined, and the algorithm selects the member's section from this list. Besides finding the appropriate sections, the algorithm tries different layouts of placing the walls in each span simultaneously. After finishing the iterations, the algorithm finds the best sections with the best layout of walls in a frame according to the mentioned objective function. The results of both algorithms are compared at the end of the process. Modified DE illustrated better performance than the Bat algorithm. For medium- and high-rise structures, the modified DE proposes more optimal designs. However, in a low-rise structure, the exact design is determined by both algorithms.

End-to-end point cloud-based segmentation of building members for automating dimensional quality control

A frequent and accurate quality inspection procedure to assess the quality requirements during the life cycle of buildings is crucial. Among different quality measures, the dimensional quality that involves spatial features of buildings is of significant importance. However, the traditional manual inspection of dimensional quality in buildings is unreliable and tedious. Thus, this study presents an end-to-end method for quality inspection of building structural members using point cloud datasets. The proposed method, first, detects and labels structural members within the point cloud based on a set of domain-specific geometric and semantic definitions. Then, each structural member's section width, height, and length are obtained with the proposed bounding box method. Experiments on three real-world buildings' point clouds with various geometric features and noise levels, occlusion, and outliers were also conducted, illustrating the performance efficiency and accuracy of the proposed model for dimensional quality inspection of building structural members.

Microbiostratigraphy of Miocene Guri Member of the Mishan Formation in the Bandar Abbas area, SE Zagros, Iran

Three sections of Guri Member of the Mishan Formation in the Bandar Abbas area are investigated for foraminifera biozonation and lithostratigraphic correlation. The base of Guri Member conformably overlies Gachsaran Formation (or Razak Formation in some sections), whereas the top of the member is overlain by marls. Thirty-four foraminifer species are identified and prove the age of Burdigalian for the Guri Member in the Gery Sheikh and Anguran sections and Burdigalian–Langhan range in the Bāz section. Two assemblage zones are recognized based on the distribution range of species. Correlation to other sections shows the eastward marine progression and age change from the Burdigalian in the west to the Burdigalian–Langhian in the east of Bandar Abbas area.

Investigations on the influence of load width on web compression buckling strength of wide-flange steel members

A comprehensive study on web-compression buckling strength of wide-flange steel members subjected to concentric transverse loads spread over lengths longer than member section depth is presented in this paper. Calculation methodologies previously developed for web-compression-buckling strength of wide-flange steel members were established for use in beam-to-column moment connections, where the load width is relatively very narrow compared to the depth of the section, therefore does not include load width as a parameter in strength equations. More recently developed calculation procedures that account for load widths are typically limited to member section depth and are merely based on numerical models, and lack experimental evidence that validates these models. This study presents experimental research on steel wide-flange members subjected to transverse compression loading by having the load length as the primary variable. Experiments were conducted on specimens with measured imperfection levels and provided results on the buckling strength, displacement, and strain variation of the web portion during testing. The experimental program also investigated the potential of creep under sustained loading on web compression buckling strength of wide flange members at load levels near buckling strength. Benchmark numerical models using the finite element method were developed using the test results to obtain insights into the observed behavior and were employed in conducting numerical parametric studies to investigate the sensitivity of results due to load width and the angle of the applied load for various cross sections. The results obtained from the experimental and numerical studies were compared with the calculation methods provided in the North American and European design codes to evaluate their accuracy. The parametric study results were also used to develop an analytical calculation procedure for estimating the web-compression-buckling strength of steel wide-flange shapes subjected to vertical and inclined loading.

Influence of Variations in Job Description on Organizational Performance in Nyanchwa Adventist College in Kisii County, Kenya

The performance of an organization is directly linked to those who work for it hence hiring unqualified staff can be costly in the long run. Nyanchwa Adventist College enrolment trend has been going down for the last five years despite the many efforts put by marketing and outreach programs to restore it. Financial performance depends on the student enrolment given that the college does not receive any external funding. The purpose of the study was to analyse the variations in staff recruitment strategies on performance at Nyanchwa Adventist College in Kisii County, Kenya. Descriptive survey design will be employed in the study. The target population will be the 158 staff and students at Nyanchwa Teachers Colleges. Stratified random sampling was used as it covers all sections of staff and members of management that will give a sample size of 113 using the Israel formula. Both Primary and Secondary data were availed using questionnaires and interviews. The reliability for the research instruments were determined by Cronbach's alpha through Test-retest method where a value more than 0.70 was considered reliable. Validation was determined by the supervisor and data collection experts. Data was analysed using both inferential and descriptive statistics that was presented in percentage, mean, standard deviations and tables. The results obtained from the study were used to improve the recruitment process, thus reversing the declining enrolment trends in order to boost the financial base. The research findings indicate that the majority strongly agreed that the organizations’ workers are highly qualified and they understand their job descriptions, this is because there is proper supervision which helps each employee to learn and follow their job description. Variation in employee qualification on organizational performance, the result showed that the majority strongly agreed that the organization employs only qualified staff for the betterment of the organization. It is up to the management of Nyanchwa College to upgrade all employees for better productivity

Thermal response of steel framing members in open car park fires

For open car park structures, adopting a performance-based structural fire design is often justified and allowed because the fire does not reach flashover. However, this design approach requires an accurate assessment of temperatures in structural members exposed to car fires. This paper describes a numerical study on the thermal exposure on steel framing members in open car park fires. Steel temperatures are computed by the coupling of computational fluid dynamics and finite element modeling, and by analytical models from the Eurocodes. In addition, the influence of galvanization on the steel temperature evolution is assessed. Results show that temperatures in unprotected beams and columns are influenced by the section geometry, car fire scenario, modeling approach, and use of galvanization. Galvanization slightly delays and reduces peak temperature. Regarding the different models, CFD-FEM (CFD: computational fluid dynamics, FEM: finite-element method) coupled models predict lower temperatures than the Hasemi model, because the latter conservatively assumes that the fire flame continuously touches the ceiling. Further, the Hasemi model cannot account for the effect of reduced emissivity from galvanization on the absorbed heat flux. Detailed temperature distributions obtained in the steel members can be used to complete efficient structural fire designs based on the member sections, structure layout, and use of galvanization.

Geometry of some moduli of bundles over a very general sextic surface for small second Chern classes and Mestrano-Simpson conjecture

Let S⊂P3 be a very general sextic surface over complex numbers. Let M(H,c2) be the moduli space of rank 2 stable bundles on S with fixed first Chern class H and second Chern class c2. In this article we study the configuration of certain locally complete intersection zero-dimensional subschemes on S satisfying Cayley-Bacharach property, which leads to the existence of non-trivial sections of a general member of each component of the moduli space for small c2. Using this study we will make an attempt to prove Mestrano-Simpson conjecture on the number of irreducible components of M(H,11) and prove the conjecture partially. We will also show that M(H,c2) is irreducible for c2≤10.

Sustainable Recovery: Updating the SPE Business Model

As I mentioned in a previous column, the SPE Board of Directors and leadership are reviewing and updating the SPE Strategic Plan. This is a periodic exercise to define the strategic goals that will allow us to better meet member expectations and industry needs in the next 3 to 5 years. The current strategic plan was developed in 2017/2018 on the heels of three very difficult years for the industry, our members, academia, and SPE. Since that time, the industry has experienced even more hardship and changes like never before. The world we live in is not the same. The SPE Strategic Plan to be developed needs to take these issues into consideration and give SPE a solid foundation to best serve our members’ needs into the future using a financially sustainable model. For more than 30 years, SPE’s main source of revenue has been events. Although SPE quickly ramped up virtual programming in 2020, it did not make up for in-person events such as the Offshore Technology Conference, Offshore Europe, and the International Petroleum Technology Conference. This graph (developed from SPE financial data) illustrates that from FY2010 (April 2009 to March 2010) SPE had relied on events for at least 70% of its revenue. It also shows how revenue from events is used not only to pay for events but also publications (advertising has fallen dramatically) and for member programs and services. The graphic for Revenue Categories splits event revenues into corporate exhibit/sponsorship (the majority) and registration for comparison with dues and all other revenue sources. Dues only amount to approximately 15% of SPE’s revenue, except during the pandemic in FY2021. FY2022 was closer to the typical pre-COVID percentage, and the forecasts for FY2023 and FY2024 are projected to be the same. As a result, we need to review and diversify SPE revenue streams. This may mean new programs and services, markets, membership categories, etc. As our traditional sources of revenue evolve, they must be supplemented if we are to maintain or even add new services. Over the period of July to August, we have set up a plan for the development of the updated strategic plan which involves interviews of different SPE stakeholders, including leaders of industry companies and a cross section of members, students and academia, regional and technical sections, as well as near-members (who participate in the Society’s events without being members). A channel is being established on SPE Connect for individual members to give their feedback on topics related to the strategic plan. We will post thoughtful discussion topics to gain insight from members. If you are not familiar with SPE Connect, please log on and join the discussion. We look forward to hearing our members’ perspective on the future of our Society. As always, I welcome your feedback at president@spe.org.

Experimental and Finite Element Study on 7A04 Aluminum Alloy Tube Confined High Strength Concrete Long Column

7A04 aluminum alloy has high strength and strong corrosion resistance, and its quality is only 1/3 of steel. Using 7A04 aluminum alloy to replace ordinary steel tube to confined concrete, it can effectively reduce the member section, reduce the weight of the structure, and more in line with the material requirements of large span materials and high-rise buildings. In this paper, nine groups of 7A04 aluminum alloy tube confined high strength concrete long column were tested under axial compression and eccentric compression with aspect ratio and eccentricity as variables. And the corresponding ABAQUS finite element model was established. The results show that the failure phenomena of the nine groups are basically the same, and the specimen deflection curve shape is similar to the sine half-wave curve. The ultimate bearing capacity of the specimen decreases with the increase of aspect ratio and eccentricity. When the axial compression or eccentricity of the specimen is small, the variation of the longitudinal and transverse strain at the midspan is similar in the elastic stage. When the eccentricity is large, the longitudinal and transverse strain at the midspan of the specimen is obviously tensile at one side and compressive at one side at the beginning. Finally, based on the test and simulation results, a formula for calculating the bearing capacity of 7A04 aluminum alloy tube high strength concrete long columns is proposed. This formula can better predict the stable bearing capacity of the specimen, which has certain reference significance for the structural design of 7A04 aluminum alloy tube high strength concrete long columns.

Weight-strength optimization of wooden household chairs based on member section size

Weight-strength optimization of wooden household chairs was performed based on the member section size in this study. Member section sizes of the Scotch pine (Pinus sylvestris) and Oriental beech (Fagus orientalis) chairs were optimized and resulting re-manufactured optimized chairs were tested under the cyclic “front to back”, “back to front” and “backrest” loads according to American Library Association (ALA) specification. Finite element method (FEM) and MATLAB nonlinear programming were utilized for the optimization. Firstly, the internal forces and moments acting on each member were analyzed by FEM in order to obtain the maximum critical stresses in each type of member; then, optimized cross-sectional sizes of the members were determined by Gradient Descent method, and all constraints were treated with Logarithmic Barrier Functioning. As a result, the minimum section sizes of members were determined, and cyclic performance tests were performed to determine whether the optimized chairs were strong enough to carry the acceptable loads. According to the results, member section size of both beech and pine chairs could be significantly reduced. The reduction was 32 % in the total weight and volume for beech chairs while 16 % for pine chairs without sacrificing the performance required for domestic usage by ALA. In conclusion, the method used is suitable for the optimization of furniture frames, making it lighter and reducing the material costs.

"We're Constantly Learning": Identifying and Disrupting White Supremacy Within a Victim Services Organization.

Many victim service organizations are seeking to realign service delivery around principles of racial equity. Dismantling institutional racism is a complex, intensive, and long-term process. Therefore, despite this imperative from the field, our knowledge about how social service organizations can effectively advance anti-oppressive practice is limited. This study examined victim advocate perspectives on the role institutional racism played within their work and the supports needed to undo institutional racism within their organization. Six focus groups were conducted with a meaningful cross section of staff members (n = 53) across the organization. Semi-structured interview guides included questions in four domains: (1) racism within client work, (2) challenges to addressing racism, (3) effective solutions, and (4) helpful organizational supports. Transcripts were thematically analyzed using modified constructivist grounded theory methods. Two overarching themes, Identifying Institutional Racism in the Workplace and Advancing Anti-racist Practice, and six subthemes emerged from the analysis. Advocates identified that naming and becoming comfortable talking about race was essential. Further, they believed it was important to acknowledge the ways in which that racism was implicitly built into helping systems at large. Advocates explored how internalized racial stereotypes influenced interactions between black, indigenous, and people of color (BIPOC) and white advocates and their clients in complex ways. Advocates highlighted organizational efforts that supported ongoing personal reflection, the creation of an accountable community, and staff empowerment within the organization as being critical to advancing anti-racist practice. Some advocates also wanted to see the organization move further in the direction of standing with BIPOC communities, particularly around criminal justice concerns. Findings provide important timely insights into how institutional racism manifests within victim service organizations and what organizational actions encourage anti-oppressive practices and culture.

Parametric study of Unstiffened multi-planar tubular KK-Joints

Multi-planar tubular joints became widely used in steel structures especially in industrial and offshore project. However, the current design procedures are still not accurate enough and depend on studying each plan separately and adjust the joint capacity using some correction factor. The aim of this research is to present a mathematical formula to calculate the capacity of symmetrical loaded multi-planar KK joint. A verified ANSYS model was used to generate 172 records for parametric study with different geometry, member sections and material properties. The outputs of the parametric study were analyzed using (GRG) solving technique to develop the final predictive model. The novelty of the developed model is it can predict the actual joint capacity as 3D joint not as approximated 2D joint as previous literatures. The developed model consists of two equations based on failure mode. One for local chord failure where the chord thickness is less than 25 times its diameter and the other for global chord failure if that ratio is more than 25. The results of the developed formula were compared with experimental test results and showed average accuracy of 92.5%.

An 8-Nodes 3D Hexahedral Finite Element and an 1D 2-Nodes Structural Element for Timoshenko Beams, Both Based on Hermitian Intepolation, in Linear Range

The following article presents the elaboration and results obtained from a 3D finite element, of the 8-node hexahedron type with 6 degrees of freedom (DOF) per node (48 DOF per element) based on third degree Hermitian polynomials, and of a 2-node structural element, with 6 DOF per node (12 DOF per element), based on third degree Hermitian polynomials and the theory of Timoshenko for beams. This article has two purposes; the first one is the formulation of a finite element capable of capturing bending effects, and the second one is to verify whether it is possible to obtain the deformation of the beam’s cross section of a structural member of the beam type, based on the deformations of its axis. The results obtained showed that the 8-node hexahedron FE was able to reproduce satisfactory results by simulating some cases of beams with different contour and load conditions, obtaining errors between 1% and 4% compared to the ANSYS software, educational version. Regarding the structural element of the beam type, it reproduced results that were not as precise as the FE Hexa 8, presenting errors of between 6% and 7% with regard to the axis but with error rounding between 10% and 20%.

LCRR Compliance Involves More Than Lead Service Lines

LCRR Compliance Involves More Than Lead Service Lines

A Novel Experimental Setup, Modelling and Static Behaviour of Cable-Supported Pipe Systems

Large spatial requirements in both onshore and offshore necessitate the investigation of the structural suitability of Cable-supported pipe system (CSPS) for transmission of fluids. This paper presents a novel experimental setup and finite element modelling of the CSPS structure. The experimental setup involves the loading of the structure using pipe clamp loading pad. Scale down models, six scenarios accounting for the effect of mid span depth-span, number of truss modules, member sections, and single and double tubes pipe sections are presented subject to cable tension, elastic and ultimate loading of the structure. The load– displacement responses of the six scenarios shows elastic responses and within limit stress until joint failure at ultimate load. Thus, the structure possesses the strength that can support its service life until loaded to the ultimate limit of the joints. The failure mode of the structure suggested the need for the cable-truss joints to be design against sudden failure. Parametric evaluation based on member section properties reveals significant deformation when the cable section is reduced compared to other member sections. The limit displacement of 64.8m span length (L) in comparison to other cable-supported structures is within L/600 - L/250, subject to check in different scenarios.

Effect of Wind Loads on Collapse Performance and Seismic Loss for Steel Ordinary Moment Frames

The aim of this study is to investigate the effect of wind loads on the seismic collapse performance and seismic loss for steel ordinary moment frames (OMFs). For this purpose, 9-, 12-, 15-, and 18-story steel OMFs are repeatedly designed for (1) gravity load + seismic load, (2) gravity load + seismic load + wind load (wind speed = 44 m/s), and (3) gravity load + seismic load + wind load (wind speed = 55 m/s). The seismic collapse performance and seismic loss of OMFs are evaluated using the procedures in FEMA P695 (FEMA, 2009) and FEMA P58 (FEMA, 2018), respectively. Steel OMFs designed with consideration of wind loads have larger member sections than corresponding steel OMFs designed without consideration of wind loads as expected. Although member sections are increased when wind loads are considered, the growth in the maximum base shear force and lateral stiffness of OMFs are insignificant. Unlike our expectation, OMFs designed with consideration of wind loads have higher expected annual loss (EAL) than corresponding OMFs designed without consideration of wind loads.

Structural Weight and Stiffness Optimization of a Midibus Using the Reinforcement and Response Surface Optimization (RSO) Method in Static Condition

Midibuses are medium-sized buses widely used for transportation purposes in Asia and Africa. However, most midibuses are locally built and indirectly regulated through inspecting the end product (finished bus) during licensing for the public transport business in Ethiopia. Due to lack of engineering analysis and testing, low stiffness and overweight of midibus were compromised. This research was aimed at analyzing and optimizing the midibus structure using the reinforcement and response surface optimization (RSO) method for pure bending and torsion loading cases. Results show that the maximum deformation occurred at the roof section of the original structure during both loading cases. Furthermore, the reinforcement design was found by replacing the cross section and layouts of structural members and adding reinforcements for the most suitable location of the original structure. Response surface optimization with the multiobjective genetic algorithm (MOGA) method in ANSYS DesignXplorer was performed on the reinforced structure to maximize the bending and torsional stiffness with reduced weight. The bending stiffness of the reinforced and optimized structure increased by 41.65% (1911.4 N/m) and 10.02% (651.7 N/m), respectively. In addition, the torsional rigidity or stiffness of the bus structure was improved by 12.56% (173.31 Nm/deg) via reinforcement design. Moreover, the torsional stiffness of the optimized (RSO) model was increased by 3.29% (51.07 Nm/deg). Reinforcement design was effectively reduced by 5.23% of the structure’s weight. Moreover, the RSO method has also decreased the weight of the reinforced structure by 2.64%.