scholarly journals The Performance of Preloaded Bolts in Seismically Prequalified Steel Joints in a Fire Scenario

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5079
Author(s):  
Roberto Tartaglia ◽  
Mario D’Aniello ◽  
Marco Andreini ◽  
Saverio La Mendola
Keyword(s):  
Finite Element ◽  
Seismic Design ◽  
Finite Element Analyses ◽  
Fire Performance ◽  
Shear Forces ◽  
Design Rules ◽  
Rotation Capacity ◽  
Geometrical Imperfections ◽  
Seismic Scenarios ◽  
Steel Joints

Seismically pre-qualified beam-to-column joints guarantee large ductility in seismic scenarios thanks to the effectiveness of the design rules and technological requirements that are devoted to avoiding the failure of brittle components (i.e., bolts and welds). However, their performance under different severe actions like those induced by fire has not been properly investigated. Therefore, a parametric study based on finite element simulations has been carried out with the aim to verify the effectiveness of local details of seismically prequalified joints under fire. Finite element analyses were carried out on beam-to-column assemblies sub-structured from a reference archetype building accounting for both material and geometrical imperfections. The bolts’ internal actions were monitored in all the investigated specimens varying the applied vertical loads. The results show that the seismic design rules adopted to size the bolts are effective to resist the large increase in shear forces in the bolts occurring under fire. Thus, the investigated joints provide satisfactory ductility and rotation capacity at high temperature preventing the failure of bolts; further analysis could be conducted to investigated the fire performance of the investigated joints in a seismic scenario.

scholarly journals Additive Manufacturing and Mechanical Performance of Trifurcated Steel Joints for Architecturally Exposed Steel Structures

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1901
Author(s):  
Pengfei He ◽  
Wenfeng Du ◽  
Longxuan Wang ◽  
Ravi Kiran ◽  
Mijia Yang
Keyword(s):  
Finite Element ◽  
Additive Manufacturing ◽  
Process Parameters ◽  
Mechanical Performance ◽  
Steel Structures ◽  
Mechanical Tests ◽  
Test Method ◽  
Finite Element Analyses ◽  
Steel Joint ◽  
Steel Joints

Additive Manufacturing (AM) technology has unique advantages in producing complex joints in architecturally exposed steel structures. This article focuses on the process of manufacturing and investigating the mechanical properties of a reduced scale model of a trifurcated joint using Selective Laser Melting (SLM) method and mechanical tests, respectively. The orthogonal test method was used to optimize the main AM process parameters. Then the trifurcated steel joint was printed using the optimal process parameters and treated by solid solution and aging treatment. To investigate the mechanical performance of the printed joint, an axial compression test and complimentary finite element analyses were carried out. Failure processes and failure mechanisms of the trifurcated steel joint were discussed in detail. The research results show that the preferred process parameters for printing 316L stainless steel powder are: scanning power 150 W, scanning speed 700 mm/s, and scanning pitch 0.09 mm. Using these AM parameters, trifurcated steel joints with good surface quality, geometrical accuracy and tensile strength are obtained after heat treatment. Our mechanical tests and Finite element analyses results indicate that the failure mechanism in the AM trifurcated joint are similar to those of cast steel joints. Based on these results, we conclude that the AM technology serves as a promising new way for the fabrication of joints with complex geometries.

scholarly journals Numerical study of inelastic buckling behavior of rectangular steel plates with circular openings under shear forces

2019 ◽  
Vol 258 ◽  
pp. 05026
Author(s):  
Rajawali M Akbar ◽  
Bambang Suryoatmono
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Steel Plates ◽  
Steel Beam ◽  
Circular Opening ◽  
Finite Element Analyses ◽  
Shear Forces ◽  
Inelastic Buckling ◽  
Buckling Behavior ◽  
Von Mises

Cellular steel beam is flanged steel beam with circular openings of uniform diameter and distance between each opening. The main benefit of such beam is to reduce the structural weight without reducing the strength significantly. A rectangular steel plate with circular opening is frequently used as a model of a web panel of such beam with vertical web stiffeners. The dimension of the plate is the dimension of the web bounded by top and bottom flanges and two adjacent vertical stiffeners. In this research, finite element method is utilized to perform inelastic buckling analyses of rectangular steel plates with circular openings under shear forces along all four edges assuming steel as elastic-perfectly-plastic material with yield stress of 250 MPa. Both nonlinear geometry and nonlinear material are considered in the analyses. The objective of this research is to study buckling behavior of the plate in terms of buckling mode, critical load, and Von Mises (effective) stress distribution. The buckling shear loads of the plates of various length-to-width ratios of the plate (1.0, 1.25, and 1.50) and various opening-diameter-to-plate-width ratios (0.00, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50) have been obtained from the analyses. The deformation and Von Mises stress distribution at every load level have been obtained as well from the finite element analyses. Equation to predict inelastic buckling shear force of a rectangular steel plates with circular opening under shear forces is proposed in this study. Verification of the method has been performed by comparing shear buckling loads resulted from finite element analyses with the analytical results in the elastic range.

Ultimate Load Test and Analysis of a Retrofitted Model Steel Dome

1998 ◽  
Vol 13 (2) ◽  
pp. 53-63
Author(s):  
Hewen Li ◽  
Lewis C. Schmidt
Keyword(s):  
Finite Element ◽  
Ultimate Load ◽  
Load Capacity ◽  
Load Test ◽  
Finite Element Analyses ◽  
Loading Test ◽  
Ultimate Load Capacity ◽  
Geometrical Imperfections ◽  
Hexagonal Grids ◽  
Post Tensioned

This paper concerns the test and analysis of a retrofitted post-tensioned and shaped steel dome that failed in an original loading test. The post-tensioned and shaped steel dome was formed by a post-tensioning operation from a planar layout constituted of hexagonal grids. After its first loading to failure, the dome was retrofitted in situ. The retrofitting method and the results of a subsequent ultimate load test and nonlinear finite element analyses of the retrofitted dome are presented. It is found that the retrofitted dome has a much greater ultimate load capacity than the original dome. The results of finite element analyses show that the prestress member forces caused during shape formation can cause a reduction of ultimate load capacity, and that the post-tensioned and shaped steel dome investigated here is sensitive to geometrical imperfections. It is also noted that the retrofitting process can be used to erect a domic structure from a near flat layout. The proposed method of considering prestress forces can be useful in nonlinear analysis of structures involving prestress forces.

Comparison Between the ASME Code NB-3600 Piping Design Branch Connection Stress Analyses and Finite Element Analyses

2015 ◽  
Author(s):  
Umar Faraz ◽  
Robert Gurdal
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Branch Pipe ◽  
Finite Element Analyses ◽  
Moment Stress ◽  
Design Rules ◽  
Pipe Cross Section ◽  
Class 1 ◽  
Asme Code ◽  
Stress Analyses

Stresses in Class 1 branch connections that consist of large bore run pipe with a reinforced branch nozzle should rarely be limited by the run–branch interface stresses. The end of the “branch nozzle – branch pipe” interface is the location on the branch nozzle one would expect to see the limiting stress. Therefore, it is important that reasonable Design Rules are maintained in the ASME Code Section III for the stress analyses of the Class 1 Piping branch connections to avoid over-predicting the “run pipe - branch nozzle” interface stresses. This will allow the analysts to concentrate on load reductions needed in a logical manner. In Class 1 Piping Design, the calculation of the branch total stress due to the moments is the result of the sum of the stresses from the run moment and of the stresses from the branch moment with these branch moment stresses being calculated using either the branch pipe cross-section or the branch nozzle cross-section. This in itself is already severe, when compared with other Piping Design Rules for branch connections. In addition, starting with the ASME Code year 2002, the branch-side moment stress is based exclusively on the branch pipe cross-section, which leads to a higher moment stress, and this higher moment stress is still absolutely added to the run-side moment stress. As indicated in that ASME Code year 2002 and beyond, this addition is independent of the length of the branch nozzle reinforcement. This leads to total moment stresses that are the sums of moment stresses that do not occur at all at the same location. The purpose of this technical paper is to compare a) the stresses calculated with the earlier more correct Class 1 Piping methodology from 2001 and before 2001; b) the stresses calculated with the more recent and more severe Class 1 Piping methodology; and c) the stresses from finite-element analyses. Conclusions are provided on what should be done for the future Class 1 Piping Design methodology of branch connections.

Design of flexure revolute joint based on compliance and stiffness ellipsoids

2021 ◽  
pp. 095441002110169
Author(s):  
Jing Zhang ◽  
Hong-wei Guo ◽  
Juan Wu ◽  
Zi-ming Kou ◽  
Anders Eriksson
Keyword(s):  
Finite Element ◽  
Single Point ◽  
Synthesis Method ◽  
Nonlinear Finite Element ◽  
Finite Element Analyses ◽  
Rotational Stiffness ◽  
Rotational Angle ◽  
Parameterized Model ◽  
Flexure Joints ◽  
Translational Stiffness

In view of the problems of low accuracy, small rotational angle, and large impact caused by flexure joints during the deployment process, an integrated flexure revolute (FR) joint for folding mechanisms was designed. The design was based on the method of compliance and stiffness ellipsoids, using a compliant dyad building block as its flexible unit. Using the single-point synthesis method, the parameterized model of the flexible unit was established to achieve a reasonable allocation of flexibility in different directions. Based on the single-parameter error analysis, two error models were established to evaluate the designed flexure joint. The rotational stiffness, the translational stiffness, and the maximum rotational angle of the joints were analyzed by nonlinear finite element analyses. The rotational angle of one joint can reach 25.5° in one direction. The rotational angle of the series FR joint can achieve 50° in one direction. Experiments on single and series flexure joints were carried out to verify the correctness of the design and analysis of the flexure joint.

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