Parametric Study of Static Strength of Multiplanar KK-Joints：Square Chords and Circular Braces

2011 ◽  
Vol 250-253 ◽  
pp. 1527-1532
Author(s):  
Ai Guo Chen ◽  
Wei Liang Huang ◽  
Rui Zeng Shan ◽  
Qing Shan Yang
Keyword(s):  
Parametric Study ◽  
Large Scale ◽  
Failure Modes ◽  
Numerical Models ◽  
Axial Loading ◽  
Steel Structure ◽  
Geometric Parameters ◽  
Truss Structures ◽  
Hollow Section ◽  
Circular Hollow Section

Pre-stressed spatial tubular truss system is adopted in steel roof truss structures of China International Exhibition Center New Venue. Bottom chord joints are multiplanar KK-joints consisting of chord with square hollow section and brace with circular hollow section. However, not only that relatively little research has been carried out on such joints, but also that no detailed design guidance on KK-type joints consisting of chord with square hollow section and brace with circular hollow section can be found Current design code for steel structure (GB 50017-2003). This paper reports the study into the strength of this type of KK-joints under axial loading. The numerical models were adopted, and several various geometric parameters which affect the strength and failure modes, were investigated. It was indicated that the geometric parameters affects significantly the ultimate capacity and failure modes of the joints. The varied relationship of the strength and failure mode with parameter varying was studied in detail. The results of the work presented provide initial discussion on behavior of this type of KK-joints and lay the foundation for a future large-scale parametric study and put out design formula.

FEM Modeling of End-Plate Assembling Bolt Connections of CHS Profiles

2015 ◽  
Vol 723 ◽  
pp. 76-80
Author(s):  
Miroslav Rosmanit ◽  
Anežka Jurčíková
Keyword(s):  
Analytical Solution ◽  
Failure Modes ◽  
Numerical Models ◽  
Simplified Model ◽  
Fem Modeling ◽  
Hollow Section ◽  
Accurate Model ◽  
End Plate ◽  
The Common ◽  
Circular Hollow Section

Two different numerical models of the common truss-type assembling joints of CHS (circular hollow section) profiles were created – simplified model of joint and more accurate model which corresponds to the experimental specimens. Models with different end-plate thicknesses and consequently with different failure modes were solved. The results obtained from numerical models were compared with the analytical solution of such joints using the Eurocode procedure recommended in EN 1993-1-8. These results are planned to be verified and further developed based on experimental results.

Axial strength of steel circular hollow section (CHS) X-joints strengthened by flanged larger pipe

2020 ◽  
Vol 47 (3) ◽  
pp. 301-316
Author(s):  
Peter Gerges ◽  
Sameh Gaawan ◽  
Ashraf Osman
Keyword(s):  
Finite Element ◽  
Parametric Study ◽  
Thickness Ratio ◽  
Finite Element Models ◽  
T Joints ◽  
Hollow Section ◽  
Axial Strength ◽  
Structural Joints ◽  
Circular Hollow Section ◽  
Steel Design

In steel design, enhancing the structural joints’ capacity is considered a challenge that faces the designer. This challenge becomes more difficult when it comes to enhancing the capacities of circular hollow section (CHS) joints due to their closed nature that complicates the strengthening process. Recent research related to strengthening T-joints by utilizing two outer hollow ring flanges welded to additional pipe showed that this technique can significantly improve the joints’ strength. In this study, the utilization of this technique is extended for enhancing the axial strength of CHS X-joints. In this regard, a parametric study using finite element models was carried out to investigate the different design aspects that might affect the behavior of strengthened X-joints. The examined parameters included, the ring flange diameter, the stiffening pipe thickness and length for different brace diameter-to-chord diameter ratios and chord diameter to double chord thickness ratio. The results demonstrated that these strengthened X-joints gained significant axial strength that reached up to three times the axial strength of the unstrengthened joints. Guidelines for proper detailing of such strengthening scheme were provided. Finally, an equation that estimates the axial strength of strengthened joints was established based on the achieved results.

scholarly journals Numerical Analysis of Axial Cyclic Behavior of FRP Retrofitted CHS Joints

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 648
Author(s):  
Mohammad Alembagheri ◽  
Maria Rashidi ◽  
Amin Yazdi ◽  
Bijan Samali
Keyword(s):  
Numerical Analysis ◽  
Welding Process ◽  
Axial Loading ◽  
Cyclic Behavior ◽  
Buckling Mode ◽  
Compression Load ◽  
Hollow Section ◽  
Plastic Failure ◽  
Frp Composite ◽  
Circular Hollow Section

This paper aims to numerically investigate the cyclic behavior of retrofitted and non-retrofitted circular hollow section (CHS) T-joints under axial loading. Different joints with varying ratios of brace to chord radius are studied. The effects of welding process on buckling instability of the joints in compression and the plastic failure in tension are considered. The finite element method is employed for numerical analysis, and the SAC protocol is considered as cyclic loading scheme. The CHS joints are retrofitted with different numbers of Fiber Reinforced Polymer (FRP) layers with varying orientation. The results show that the welding process significantly increases the plastic failure potential. The chord ovalization is the dominant common buckling mode under the compression load. However, it is possible to increase the energy dissipation of the joints by utilizing FRP composite through changing the buckling mode to the brace overall buckling.

Overlapped K Joints in Circular Hollow Sections Under Axial Loading (An Investigation of the Factors Affecting the Static Strength Using Numerical Modeling)

1996 ◽  
Vol 118 (1) ◽  
pp. 53-61 ◽  
Author(s):  
E. M. Dexter ◽  
M. M. K. Lee ◽  
M. G. Kirkwood
Keyword(s):  
Failure Modes ◽  
Load Transfer ◽  
Numerical Models ◽  
Axial Loading ◽  
Static Strength ◽  
Test Results ◽  
Factors Affecting ◽  
Current Design ◽  
The Relationship ◽  
Design Guidance

Overlapped joints are generally regarded as having higher strengths than otherwise identical, simple nonoverlapping joints because of the more efficient load transfer between braces. However, not only that relatively little research has been carried out on such joints, the few test data from which current design guidance was derived has also been recently rejected. This paper reports the first phase of a parametric finite element study into the strength of overlapping K joints under axial loading. The numerical models were validated and calibrated against existing gap and overlapped K joint test results, and various factors which affect the relationship between the strength and the overlap amount, such as boundary restraints, hidden welds, loading hierarchy, and failure modes, were investigated. The results of the work presented lay the foundation for a future parametric study.

Limit States for Deepwater Flowlines and Risers: Review of the Research Activities at the Submarine Technology Laboratory/COPPE

2003 ◽  
Author(s):  
S. F. Estefen ◽  
T. A. Netto ◽  
I. P. Pasqualino
Keyword(s):  
Ultimate Strength ◽  
Large Scale ◽  
Failure Modes ◽  
Numerical Models ◽  
Experimental Tests ◽  
Limit States ◽  
Collapse Pressure ◽  
Research Activities ◽  
Structural Resistance ◽  
Buckle Arrestors

Research activities related to the limit states of flowlines and risers conducted at the Submarine Technology Laboratory / COPPE in cooperation with PETROBRAS are presented. The motivation for most of the research programs is associated with deepwater challenges arising from the rigid pipe installations at Campos Basin. Initially ultimate strength of intact pipes are investigated together with aspects related to residual strength, buckling propagation and buckle arrestors. Based on the experimental results numerical models have been correlated in order to be used to generate results for full scale steel pipes. Ultimate strength curves have been then produced as well as the analytical equation representative of these curves. Experimental tests of buckling propagation for small and large scale pipes have also been performed to obtain the bias factor for different equations proposed in the literature. Based on this study an equation for propagation pressure has been recommended. In addition, ring and cylinder buckle arrestors have been tested in order to propose an expression relating crossing over pressure with the arrestor geometries. An overview of the studies aiming at establishing the influence of the reeling method of installation on the failure modes of flowlines and steel catenary risers is presented. It is emphasized the influence of cross-section ovality and weld defect amplification due to plastic bending on collapse pressure and fatigue life, respectively. Finally, the development of a new concept of sandwich pipe for ultra deepwater, combining structural resistance and thermal insulation is discussed.

scholarly journals Experimental Study on the Static Behavior of Reinforced Warren Circular Hollow Section (CHS) Tubular Trusses

2018 ◽  
Vol 8 (11) ◽  
pp. 2237 ◽  
Author(s):  
Wenwei Yang ◽  
Jiankang Lin ◽  
Ni-na Gao ◽  
Ruhao Yan
Keyword(s):  
Experimental Study ◽  
Carrying Capacity ◽  
Truss Structures ◽  
Load Carrying Capacity ◽  
Static Behavior ◽  
Hollow Section ◽  
Surface Plasticity ◽  
Load Carrying ◽  
Circular Hollow Section ◽  
Chord Member

For truss structures, the question of whether to weld hidden welds or not has been controversial. In the actual construction process of truss structures, the members are usually spot welded in place on the assembly platform, and then welded as a whole, while the hidden welds of the truss are not welded, especially for small pipe diameter trusses. Furthermore, in this study, under hidden weld unwelded conditions, two kinds of reinforcing method (adding a half outer sleeve on each joint and filling concrete into the chord members) are adopted to achieve the purpose of strengthening the truss. Therefore, this paper presents an experimental study on the static behavior of four types of Warren tubular trusses made of CHS members. These four types are (1) T-HW: The truss with hidden welds welded; (2) T-HN: The truss with hidden welds unwelded; (3) TS-AS: The truss strengthened on the basis of T-HN by adding a half outer sleeve on each joint; (4) TS-FC: The truss strengthened on the basis of T-HN by filling concrete into the top and bottom chord members. The mechanical behavior, failure mode, bearing capacity, and load-displacement of all specimens were investigated. The surface plasticity of the bottom chord member, the weld fracture around tubular joints at the bottom chord member, and the bending deformation of the bottom chord member were observed in the tests. Compared with the T-HW specimen, the load carrying capacity of the T-HN specimen decreased by 18%. On the other hand, the T-HN specimen has better deformability than the T-HW specimen. The reinforcing method of adding a half outer sleeve on each joint and filling concrete into the chord members can effectively improve the load carrying capacity and stiffness of the truss, thus reducing the overall deformation of the truss, but the reinforcing method of filling concrete into the chord members is more efficient.

Static Strenght of Doubler Plate Reinforced Tubular K-Joints under Bending Load

2012 ◽  
Vol 166-169 ◽  
pp. 645-648
Author(s):  
Wei Ning Sui ◽  
Xin Long Zhang ◽  
Guo Chang Li ◽  
Xue Bai
Keyword(s):  
Ultimate Strength ◽  
Static Strength ◽  
Geometric Parameters ◽  
Hollow Section ◽  
Numerical Studies ◽  
Bending Load ◽  
Circular Hollow Section

Abstract: In order to study static strength of doubler plate reinforced circular hollow section (CHS) K-joints, experimental and numerical studies conducted by the authors. The effects of parameters Δ (the ratio between the length of doubler plate and the diameter of the brace) and α (the width of the doubler plate) on CHS K-joints subjected to bending load have been investigated and reported by the authors. It is found that the ultimate strength of a CHS K-joints reinforced with appropriately proportioned doubler plates can be up to 2 ratio to its un-reinforced counterpart. Reasonable geometric parameters of the doubler plate can make the chord, brace and doubler plate work together to bear the external bending load. The width and length parameter of the doubler plate, however, have no effect on the stiffness of the reinforced K-joints.

scholarly journals Elliptical hollow section T and X connections

2012 ◽  
Vol 39 (8) ◽  
pp. 925-936 ◽  
Author(s):  
Tarana Haque ◽  
Jeffrey A. Packer
Keyword(s):  
Construction Industry ◽  
Structural Design ◽  
Failure Modes ◽  
Design Method ◽  
Design Guidelines ◽  
Preliminary Design ◽  
Hollow Section ◽  
Steel Shape ◽  
Circular Hollow Section ◽  
Angle Orientation

Elliptical hollow sections (EHS) are the newest steel shape to have emerged in the construction industry. They have been incorporated in a variety of structures around the world, including Canada, without structural design guidelines. To date, EHS are completely absent from Canadian codes and guides. A possible application of EHS is within truss-systems and, as such, a research project has been undertaken to investigate the behaviour of EHS-to-EHS welded connections. Twelve T and X connection tests have been performed to study the effect of connection angle, orientation type, and loading sense. Two methods to predict connection capacities and failure modes are investigated: an equivalent circular hollow section (CHS) approach and an equivalent rectangular hollow section (RHS) approach. The equivalent RHS approach proved to be more successful at capturing the actual failure mode of welded EHS-to-EHS connections and is therefore recommended at this time as a preliminary design method for EHS truss-type connections.

scholarly journals Confining T-joints by adding two outer hollow ring flanges welded to additional hollow circular pipe

2017 ◽  
Vol 44 (10) ◽  
pp. 783-801 ◽  
Author(s):  
Peter Gerges Melek ◽  
Mohamed Hussein ◽  
Sameh Gaawan
Keyword(s):  
Parametric Study ◽  
Diameter Ratio ◽  
Outer Ring ◽  
Circular Pipe ◽  
Compression Force ◽  
T Joints ◽  
Hollow Section ◽  
Joint Location ◽  
Circular Hollow Section ◽  
Strengthening Technique

Increasing the capacity of circular hollow section (CHS) T-joints is a challenge for the designers due to its closed nature that makes strengthening difficult as the traditional strengthening techniques focus on adding ring stiffeners inside the chord, these techniques require splitting the chord at each joint location into more than one part and this is not applicable for stiffening prefabricated and erected T-joints. This paper presents a proposed strengthening technique that is based on confining the T-joint by two outer hollow ring flanges welded to additional hollow circular pipe. A parametric study is carried out to investigate the effect of the hollow ring flanges diameter, the added elements thickness, and the spacing between the hollow outer ring flanges on increasing the capacity of T-joints for different values of β (db/d0: brace diameter-to-chord diameter ratio) when the brace is either subjected to tension or compression force. Finally, it is observed that the compressive T-joints gain up to 267% of its original capacity and the tensile T-joints gain up to 65% of its original capacity.

scholarly journals Non-Destructive Tests for the Structural Assessment of a Historical Bridge over the Tua River

2013 ◽  
Vol 569-570 ◽  
pp. 390-397 ◽  
Author(s):  
Isabel Valente ◽  
Luís F. Ramos ◽  
Kevin Vasquez ◽  
Paulo Guimarães ◽  
Paulo B. Lourenço
Keyword(s):  
Failure Modes ◽  
Dynamic Testing ◽  
Numerical Models ◽  
Dynamic Properties ◽  
Dynamic Test ◽  
Truss Structures ◽  
Design Standards ◽  
Element Analysis ◽  
Modern Design ◽  
Structural Assessment

Paradela Bridge is a metallic bridge located along the bank of the Tua River in northern Portugal. While the bridge is not currently in service, its structure is representative of many metallic truss structures built across the continent between the XIX and the XX century. Tua Line belongs to the Douro area that UNESCO recently declared as world heritage. This study acquires its importance since it might serve as an insight for the study of many other similar structures all over the country. This paper comprises a historic investigation of archived documents, an on-site survey to evaluate its present conditions, a dynamic testing and the construction and calibration of numerical models in finite element analysis (FEA) software, structural assessment and capacity rating estimation. The purpose of constructing numerical models was to evaluate the suitability of the bridge under the original loading and in accordance to modern design standards. The historical research revealed that the truss bridge was designed as a simply supported element and that a series of hand calculations were carried out on individual structural elements (e.g. main trusses, stringers and floor beams). Furthermore, a dynamic test was conducted in order to identify the global dynamic properties of the structure and to calibrate numerical models that ensure reliability and representativeness. FE models served through the structural assessment of the bridge in accordance with modern design codes and to estimate the safety of the bridge. Likewise, a nonlinear failure analysis was also conducted in order to estimate the capacity rate of the bridge and the likely failure modes.

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