Multiplanar Joint Research Articles

Unified AI-Based Predictive Models for the Ultimate Capacity of Multi-Planar Gapped KK Steel Pipe Joints

The multi-planar steel pipe joints are widely used in communication towers, industrial structures, and offshore platforms. The current design formulas consider this joint as a uniplanar joint and account for the multi-planar effect using empirical correction factors. Recent studies deal with this multi-planar joint as a 3D joint but considering certain loading conditions. Hence, the aim of this research is to develop more general AI-based predictive models for the ultimate capacity of multi-planar gapped KK steel pipe joints, considering both symmetric and asymmetric loading conditions. Three AI techniques were applied to a database of previously published works. These techniques are “Genetic Programming” (GP), “Artificial Neural Network” (ANN), and “Evolutionary Polynomial Regression” (EPR). The prediction accuracies of the developed AI models were compared against two previously published formulas. The results indicated that the developed AI models are much more accurate than the previously published formulas. Also, the results showed that both the ANN and EPR models have almost the same level of accuracy (about 92%), but the EPR model has the advantage of presenting a closed-form equation that could be implemented either manually or using software. Doi: 10.28991/CEJ-SP2024-010-07 Full Text: PDF

Bending load effects on stress concentration factor distribution of multi-planar DTKY tubular joints

The stress concentration factor (SCF) in tubular joints is an important parameter in calculating the fatigue life of offshore structures. In design practices, estimating the SCF is usually based on standard empirical formulas, providing the majority for uni-planar tubular joints, and could not be applied directly for multi-planar joint cases. Therefore, accurate SCF estimation became critical for specific multi-planar tubular joints commonly found as members of offshore platforms. More detailed analyses of complex designs are possible with the recent development of finite element analysis and supported by advanced digital computers. Thus, this research is intended to analyze the SCF of multi-planar DTKY tubular joints with finite element analysis. The local model of the tubular joint will be simulated for bending moment load cases. The results show stress distribution characteristic of the joint at both brace and chord sides. The results indicated that the SCF of the joint under the in-plane bending (IPB) loading is higher at the brace than the chord side, with values of 2.83 and 1.47, respectively. Meanwhile, under the out-of-plane bending (OPB) loading, the SCF is 2.43 at the chord saddle location and 3.54 at the brace saddle location.

The Effect of geometric parameters on stress concentration factor of a multiplanar DKT tubular joint through finite element model

It is important to consider geometric parameters on Stress Concentration Factor (SCF) at the tubular joint, especially multi-planar joint, when designing a jacket platform. Thus, a jacket platform capable to withstand the extreme environmental loads. Many researchers use the Finite Element (FE) method to analyze stress at joints and estimate the SCF with the variation of geometric parameters. That studies obtained the result that geometric parameters have significant effect on decreasing or increasing the SCF. Therefore, this study will delve the effect of geometric parameters (β, τ, and γ) on maximum SCF caused by axial loading, in-plane bending moment, and out-of-plane bending moment at DKT tubular joint. The increase of β results in the decrease in maximum SCF at brace-side and chord-side weld toe, respectively. The increase of τ and γ results in the increase in maximum SCF at brace-side and chord-side weld toe, respectively.

Stress Distribution Analysis of DKDT Tubular Joint in a Minimum Offshore Structure

A marginal field defines as an oil and/or gas field that has a short production period, low proven reservoir, and could not be exploited using existing technology. As the demand for oil and gas keeps increasing, one of the solutions to tackle the issues is to build the modified platform which came to be more minimalist to conduct the oil and gas production in the marginal field. Naturally, the minimum offshore structures are cost less but low in redundancy, therefore, pose more risks. Although the study on the minimum structures is still uncommon, there are opportunities to find innovative systems that need to have a further analysis toward such invention. Therefore, this study took the modified jacket platform as a minimum structure, and local stresses analysis by using finite element method is applied for the most critical tubular joint with multiplanarity of the joint is taking into account. The analysis was carried out using the finite element program of Salome Meca with three-dimensional solid elements are used to model the multiplanar joint. Various loading types of axial force, in-plane bending moment, and out-of-plane bending moment are applied respectively to investigate the stress distribution along the brace-chord intersection line of the tubular joint. The results show that the hotspot stress occurred at a different point along each brace-chord intersection line for each loading type. Finally, as compared to the in-plane bending moment or out-of-plane bending moment loading types, the axial force loading state is thought to generate greater hotspot stress.

Hot spot stress parametric equations for three-planar tubular Y-joints subject to in-plane bending moment

Abstract Tripod substructure is widely used in the construction of fixed offshore wind turbines (OWT). The three-planar tubular Y-joint is a significant part of this type of OWT when conducting fatigue failure checking. In-plane bending moment is one of the typical loads applied to this structure. As no relevant research aimed to study the performance of three-planar tubular Y-joints subject to in-plane bending moment before, the works done in this paper are as follows: the calculation method for hot spot stress (HSS) of multi-planar joint was discussed; an experiment was carried out to reveal the strain distribution and verify the finite element (FE) method; a data set was built up with 1920 cases by validated FE model; the analyses of geometric parameters were conducted to derive a set of design equations; the parametric equations were evaluated via a common acceptance criteria.

VESTIBULAR OCULAR THERAPY TO OPTIMIZE THE BRAIN OF A YOUNG MAN WITH ASPERGER’S

Event Abstract Back to Event VESTIBULAR OCULAR THERAPY TO OPTIMIZE THE BRAIN OF A YOUNG MAN WITH ASPERGER’S Benjamin R. Behrendt1, 2* 1 NeuroWorks Healthcare LLC, United States 2 Carrick Institute, United States BACKGROUND: A 29-year-old male presented with Asperger’s, increased anxiety, difficulty with coordination, tremors and uncontrolled movements, following directions, comprehension, finishing tasks, mental fatigue and fogginess, sound and touch sensitivity. When in a visually busy environment he experiences blurring while “zoning out”. METHODS: An extensive neurological examination and treatment protocol was performed. Significant findings included: camptocormic posture; an accentuated 10-14 Hz tremor that was evident with hand writing and with rest; tachycardia and acceleration of HR from supine to standing. Also occurring was a loss in the ability to pursuit at frequencies approaching .2 and .4 Hz; absent optokinetic (OPK) reflexive eye movements, along with significant decrease in cognitive following OPK eye movements horizontally and vertically while staring into space and significant ptosis; decrease in gain during head impulse bilaterally going from lateral to medial, however not when going medial to lateral. Using the Unified Parkinson’s Disease Rating Scale (UPDRS) he had a grade 1 with facial expression, Luria hand sequencing and foot tap, and a grade 0 finger tap, and there was a positive glabellar sign. Noted was bilateral, dysmetric cerebellar findings with finger-to-nose; alternating hand movements; and heel/shin slide seated and supine; and past pointing. Positive extinction at the shoulder/cheek, loss of graphesthesia with recognizing letters and numbers in the hands and feet was discovered. Patellar reflexes (MSR) were 3+. He had increased instability with Romberg’s, tandem and perturbed stance; an increase in toe off/springing of gait; decreased right arm swing; increased hesitations with stiffening of gait during dual tasking. Therapy targeted the right posterior canal and left anterior canal input centrally utilizing a procedure which combined times-zero viewing into posterior canal plane, pursuing leftward into times-one viewing into the left anterior canal plane; and left anterior canal repositioning to integrate central vestibular with cervical ocular structures. A prescribed set of exercises for home included somatosensory mapping; gait training with large accentuated arm movements; cross crawl multiplanar joint movements; right unilateral multiplanar joint patterning; and orthogonal ocular movements. A return visit consisted of anterior canal reintegration, VOR head movements with head thrust to the right, cerebellar patterning, orthogonal eye movements, as well as, home therapies. RESULTS: Following the initial treatment he had reduced tremor; WNL Glabellar reflex; reduced muscle tone globally; reduced tremor in the hands; reduced light sensitivity; improved OPKs horizontally and vertically; and maintained loss of graphesthesia. Home program improved hand-writing, and reduced tremor. After second treatment he regained graphesthesia and somatosensory localization; no longer felt internal sense of jitters; and was less anxious and more relaxed. CONCLUSION: Connected functional neurological exam and treatment utilizing the vestibular system and somatosensory integration can significantly change the timing of cerebellum and brain output. Further investigation is warranted for the integration of vestibular ocular therapy for brain synchronization. Keywords: Aspergers, cognitive ehnancement, Vestibular Rehabilitation, Neurorehabilitation, Vestibular ocular rehabilitation, Cognition Conference: International Symposium on Clinical Neuroscience, Orlando, United States, 24 May - 26 May, 2019. Presentation Type: Poster Presentation Topic: Clinical Neuroscience Citation: Behrendt BR (2019). VESTIBULAR OCULAR THERAPY TO OPTIMIZE THE BRAIN OF A YOUNG MAN WITH ASPERGER’S. Front. Neurol. Conference Abstract: International Symposium on Clinical Neuroscience. doi: 10.3389/conf.fneur.2019.62.00053 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 02 Apr 2019; Published Online: 27 Sep 2019. * Correspondence: Dr. Benjamin R Behrendt, NeuroWorks Healthcare LLC, Marietta, United States, drben@neuroworkshealthcare.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Benjamin R Behrendt Google Benjamin R Behrendt Google Scholar Benjamin R Behrendt PubMed Benjamin R Behrendt Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. 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Experiment and design investigation of a multi-planar joint in a transmission tower

This paper focuses on a multi-planar steel tubular joint, which is in the slope change position of a new transmission tower. This slope change joint (SCJ) had six branch tubes and five chords in total, which led to complex interaction in the joint behaviour. To achieve experimental loading, a three-dimensional setup was designed for this joint. Detailed information of this SCJ and the test equipment were introduced. Then numerical model was established and validated by test results. Stress conditions of primary members, failure modes, influencing factors of the ultimate load as well as load transmission path were investigated by taking advantage of numerical analysis. Furthermore, a criterion for joint capacity was established referring to steel structure standards in different countries. Based on the established criterion, critical members were revealed and strengthened. In the end, procedures to optimize critical members and recommendations for joint design were proposed. Results proved that this SCJ can well meet the strength requirements after optimization.

Experimental and Numerical Analysis of Complex Welded Tubular DKYY-Joints

The design of multi-planar welded tubular joints is still not fully developed and very often it is not covered in design codes due to the complexity of such structures. The joint position for multi-planar tubular structures is especially critical because there are many brace members which are welded onto the chord surface. Thus, many external forces which are transferred from the braces are applied directly to the chord. Among the various multi-planar tubular joint configurations, the DKYY-joint configuration is often used in tubular space structures to form long-span roofs. However, its design, failure modes and calculations of its joint capacity are not provided in any design code. As a result, it is necessary to carry out experimental investigation and finite element numerical analysis to understand further the behavior and failure process of this type of joint. This paper details an actual practical application where a full-scale specimen is investigated experimentally in a test programme. To improve its joint capacity, reinforcements such as strengthening plates are placed inside the brace members. The chord at the joint connection is thickened to avoid local buckling. The stresses at some critical positions on the braces and on the chord are measured from strain gauges and strain rosettes to monitor the failure process and the ultimate joint capacity is determined from experimental load-displacement relationship. Experimental results show that local buckling on the chord surface at the joint is avoided effectively due to the reinforcement to the chord by increasing the chord thickness locally and placing inner circular plate inside the chord. As the stiffness of the chord at the joint is improved efficiently, failure position moves to the brace, and thus the chord is protected. Finally, finite element analysis is conducted and the numerical results are compared against those obtained from experimental measurements.

Ultrasonographic assessment of osteophytes in 127 patients with hand osteoarthritis: exploring reliability and associations with MRI, radiographs and clinical joint findings

ObjectiveTo investigate the reliability of ultrasonographic assessment of osteophytes and explore the concordance of osteophytes detected by ultrasound, MRI, conventional radiography (CR) and clinical joint examination in patients with hand...

Effect of stress concentration factors on the structural integrity assessment of multi-planar offshore tubular DKT-joints based on the fracture mechanics fatigue reliability approach

A reasonably accurate estimate of fatigue reliability is considered to be essential for offshore structures due to their high construction cost and failure consequences. In the present paper, firstly, a fracture mechanics based fatigue limit-state function is derived and effects of assigning different values to deterministic variables involved in this limit-state function on the results of reliability analysis are investigated. These deterministic variables are the material parameter, number of stress cycles, and the mean value of critical crack size. Afterwards, effects of stress concentration factors (SCFs) on the reliability of the tubular joint are studied. The SCF is one of the most important parameters in the fatigue reliability analysis, which exhibits considerable scatter. Results showed that change of the mean value of SCF, from the value typically assumed in the previous research works (=2.5) to a realistic value obtained in the present research for a widely used multi-planar joint (∼15), leads to considerable decrease in the reliability index and consequently significant increase in the probability of failure. However, change of the coefficient of variation (CoV) of SCFs, from the typically assumed value (=0.15) to a realistic value obtained in the present research (∼1.048), does not considerably affect the results.

Strength Analysis of Large-Scale Multiplanar Tubular Joints with Inner-Plate Reinforcement

For large scale multiplanar tubular joints used in practical engineering, the brace/chord intersection is a critical position as failure usually occurs here due to the weak bearing capacity of the chord in radius direction compared to the strength of the braces in axial direction. To improve the ultimate strength, different reinforcements can be used to strengthen the structures. Inner plate reinforcement is a relatively new strengthening method compared to conventional reinforcing methods. As there is no corresponding guideline which can be used for the design of inner plate reinforcing joints, it is necessary to investigate the failure mechanism of such tubular structures. Both experimental test and finite element analysis are carried out in this study to investigate the static behaviour of multiplanar tubular joint reinforced with inner plate. In the experimental work, the stresses distribution and development of the specimen is monitored, and the failure mode is observed. From the experimental results, both the failure process of the multiplanar tubular joint and the reinforcing efficiency of the inner plate were analyzed. Using finite element analysis, the failure process of the specimen is also analyzed step by step. The finite element results agree reasonably well with experimental measurements.

Strain concentrations at intersection regions of a multiplanar tubular DX-joint

A large-scale steel multiplanar tubular Double X-joint (DX-joint) specimen was tested such that its in-plane and out-of-plane braces were subjected to three different load cases of pure axial forces. The strain gradients at the joint intersection regions were measured and consequently the hot spot strain locations, and hence, the strain concentration factors (SNCFs) were determined. The shapes of the SNCF distributions and the peak SNCFs determined in the tests were found to be in good agreement with those obtained by finite element (FE) analyses, except for the load case where all the braces were subjected to axial tensile forces. In addition, the results at the peak hot-spot saddle locations were compared with those predicted using authors FE analyses, Efthymiou's influence function (IF) method (Efthymiou M. Development of SCF formulae and generalized influence functions for use in fatigue analysis. Proceedings of OTJ Conference, Surrey, UK, October 1988) and Romeijn's equations (Romeijn A, Puthli RS, De Koning CHM, Wardenier J. Stress and strain concentration factors of multiplanar joint made of circular hollow sections. Proceedings of the Second International Offshore and Polar Engineering Conference, San Francisco, USA, June 1992:384–93). Due to the multiplanar stiffening effect of the loaded out-of-plane braces, the IF method (Efthymiou M. Development of SCF formulae and generalized influence functions for use in fatigue analysis. Proceedings of OTJ Conference, Surrey, UK, October 1988) grossly overestimated the test results in the case where all the braces were subjected to axial tensile forces.

Ultimate Resistance of Unstiffened Multiplanar Tubular TT‐ and KK‐Joints

Using a database containing test results of 58 specimens, simple mathematical expressions that explain the resistance of multiplanar tube-to-tube joints with circular hollow sections under axial brace loading and sought. The joints concerned are multiplanar TT- and KK-joints consisting of two uniplanar T- or K-joints that lie in different planes. The uniplanar joints have an identical configuration and loading of the braces. Multiple regression analysis is performed to obtain prediction equations. The proposed ultimate strength equations are shown to be in good agreement with the test results. The prediction models are based on a simple mechanical model of a ring that enables an extrapolation of the geometric variables’ application ranges. The proposed ultimate strength equations are compared with existing prediction formulas. For the proposed validity ranges of the ultimate strength equations, the multiplanar coefficient μ, the factor by which the uniplanar joint strength has to be multiplied to obtain the multiplanar joint strength, ranges from 0.5 to 1.3, indicating that multiplanar effects are indeed significant.