scholarly journals An Alternative Stiffening Method for Rigid CHS L-Joints

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
Niall Holmes ◽  
Darran Kierans ◽  
Patrick Crean
Keyword(s):  
Failure Modes ◽  
Load Capacity ◽  
Local Buckling ◽  
New Method ◽  
Moment Connections ◽  
Moment Capacity ◽  
Codes Of Practice ◽  
Alternative Approach ◽  
The Moment ◽  
Better Than

The paper presents a new method of stiffening CHS L-joints and compares it against current stiffened and unstiffened moment connections. The method is derived from studying the failure modes of existing methods, typically local buckling and ovalisation of the section. Unstiffened right-angled CHS connections have been shown to be weak due to local buckling and ovalisation. Stiffing plates placed across the joint can increase the moment capacity of the section by preventing ovalisation of the section but is architecturally unsightly. An alternative approach, where a stiffening plate welded vertically inside both the column and beam, outperformed the unstiffened frame plate in terms of reduced ovalisation and increased load capacity. It was also found to perform better than the stiffened connection in terms of both vertical and horizontal deflection. However, more research is required to ensure a fully restrained connection to satisfy codes of practice and constructible.

Experimental Study of Cold-Formed Steel Moment Connections with Screw Fasteners

2019 ◽  
Vol 950 ◽  
pp. 85-89
Author(s):  
Adeline Ling Ying Ng ◽  
Zhi Yong Law
Keyword(s):  
Local Buckling ◽  
Test Results ◽  
Moment Connections ◽  
Moment Capacity ◽  
Moment Connection ◽  
Steel Moment Connection ◽  
Steel Sections ◽  
Cold Formed Steel ◽  
The Moment ◽  
Hot Rolled

A series of connection with screw fasteners were tested to study the behavior of cold-formed steel moment connection. The test specimens included hot-rolled parallel flange channels, cold-formed lipped C-Channels, and self-drilling self-fastening screws. Two different lipped C-Channels and a various number of screws per connection were used in this study. The moment-rotation behavior, rotational rigidity, and the connection capacity differed with the number of screws. The connection behaved as a pinned connection when 4 screws were used. However, local buckling was observed in the cold-formed steel sections near the connection when 8, 10 and 14 screws were used. The connection test results were compared with theoretical results calculated in accordance to the Australian Standards. None of the connection tested could achieve the moment capacity of the section connected.

The effect of end distance on the moment resistance of timber rivet connections

2003 ◽  
Vol 30 (5) ◽  
pp. 945-948 ◽  
Author(s):  
J A Hampson ◽  
H G.L Prion ◽  
F Lam
Keyword(s):  
Failure Mode ◽  
Slight Reduction ◽  
Moment Connections ◽  
Moment Capacity ◽  
Laminated Veneer Lumber ◽  
Moment Connection ◽  
Glued Laminated Timber ◽  
End Distance ◽  
Strength And Stiffness ◽  
The Moment

The results of an experimental study on moment connections with timber rivets are reported. The end distance for a four-rivet moment connection is varied in an attempt to determine the effect on the moment capacity and the failure mode. Varying the end distance did not seem to induce the occurrence of a brittle failure mode, but a slight reduction in the strength and stiffness of joint was observed. This was confirmed for specimens made with glued-laminated timber (glulam), laminated-veneer lumber (LVL), and parallel-strand lumber (PSL).Key words: wood, timber, moment, connection, brittle, end distance, glulam and rivet.

scholarly journals Ultimate Limit Design of Strengthened Steel Columns by Mortar-Filled FRP Tubes

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jian Hou ◽  
Li Song
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Load Capacity ◽  
Local Buckling ◽  
Ultimate Load Capacity ◽  
Composite Columns ◽  
Steel Columns ◽  
Frp Tube ◽  
Frp Tubes ◽  
Ultimate Limit

The present study investigated the various failure modes of strengthened steel columns by mortar-filled fiber-reinforced polymer (FRP) tubes to analytically formulate the ultimate capacities of these steel columns. A simple and effective method, wherein a mortar-filled FRP tube was sleeved outside the steel member, was also formulated to enhance the buckling resistance capacity of compressed steel members. In addition, to facilitate the connection of the column to other structural members, the length of the sleeved mortar-filled FRP tubes is less than that of the original steel columns. Theoretical analyses were also performed on the critical sections of such composite columns at their ultimate states to identify their potential failure modes, such as FRP-tube splitting at the ends or on the insides of wrapped areas, local buckling at the steel ends of transition zones, and global buckling of the composite columns. The corresponding ultimate capacity of each failure mode was then analytically formulated to characterize the critical failure mode and ultimate load capacity of the columns. The current theoretical results were compared with those from literature to validate the applicability of the developed ultimate limit design approaches for FRP-mortar-steel composite columns.

scholarly journals Numerical investigation of the cold-formed I-beams bending strength with different web shapes

2021 ◽  
Vol 16 (59) ◽  
pp. 153-171
Author(s):  
Nadia Kouider ◽  
Yazid Hadidane ◽  
Mohammed Benzerara
Keyword(s):  
Failure Modes ◽  
Bending Strength ◽  
Load Capacity ◽  
Effective Width ◽  
Large Span ◽  
Finite Element Software ◽  
Bending Load ◽  
New Process ◽  
Corrugated Web ◽  
Better Than

The wide use of cold-formed sections (CFS) in the field of steel constructions, favored by the multiple advantages they offer (lightness, ease of installation, etc.), has led us to reflect on a new process for manufacture of metal beams allowing the design of very large span hangars and a reduction in instability problems. This paper presents a study of the theoretical and numerical behavior of a large span CFS beam with different webs, a solid web, a triangular corrugated web, and a trapezoidal corrugated web. These beams are stressed by a concentrated bending load at mid-span. Numerical modeling was done using the finite element software ABAQUS. The results were validated with those theoretically found, based on the effective width method adopted in standard EN1993-1-3. The load capacity and failure modes of the beams were discussed. According to numerical and analytical analysis, corrugated web beams perform better than all other sections.

Study of Bending Capacity of an HPHT CRA-Lined Seamless Pipeline

2014 ◽  
Author(s):  
Cyprian Gil ◽  
Knut Tørnes ◽  
Per Damsleth
Keyword(s):  
Internal Pressure ◽  
Strain Localization ◽  
Local Buckling ◽  
Bending Moment ◽  
Design Criteria ◽  
Design Codes ◽  
Moment Capacity ◽  
Wide Range ◽  
Global Buckling ◽  
The Moment

A study has been performed to better understand ultimate bending moment and strain capacities of pipelines in relation to criteria defined in the design codes. An 18″ HPHT flowline was designed to undergo global buckling on uneven seabed and to resist trawl gear interference. The high temperature (155 degC) and pressure (300 bar) posed considerable design challenges for material selection and design criteria. A CRA-lined X60 CMn pipeline was selected for the project. The pipeline was of seamless manufacture for which the stress/strain characteristics are subject to the effect of Lüders bands. The DNV-OS-F101 code covers a wide range of D/t but does not specifically address Lüder’s material behaviour which could significantly reduce the bending moment capacity of pipe. The global buckling and trawl pull-over FE analysis results indicated the pipe was highly utilized, requiring excessive amounts of seabed intervention at great cost to meet the DNV LCC criteria. Detailed FE simulation of limit states for local buckling and strain localization of a 3D solid element pipe model was performed, with both Roundhouse and Lüders material properties, to investigate pipe capacity in relation to that stipulated by the design codes. The pipe moment capacity was established by obtaining the moment curvature relationship by bending the local pipe section subject to internal pressure until the maximum resistance was reached. Imperfections were introduced to initiate local buckling at the desired location. To determine strain concentration factors and strain localization, the effects of thickness changes and weld misalignment were also studied. The DNV OS-F101 LCC moment criterion formulation computes a decreasing moment capacity for increasing internal pressure. It has been suggested in the literature that this is correct for higher D/t but the criterion may be conservative for pipes with lower D/t. The combination of Lüders material with low D/t is not specifically addressed by any design code. Clarification of these aspects will provide a better understanding of the risk of failure for highly utilized seamless pipelines and allow for modified design criteria that will reduce seabed intervention costs. The results of the study showed that a higher bending moment criterion and associated strain criterion could be adopted for the design that allows for the higher initial strain caused by Lüder’s plateau. The ultimate bending moment capacity of low D/t pipe with Lüder’s material was found to be similar to that of Roundhouse material due to work hardening. In addition, it was demonstrated that the potential strength of the CRA liner could enhance the moment capacity of the seamless pipe.

Fracture Moment Strength of Reduced Beam Section with Bolted Web Connections

2007 ◽  
Vol 348-349 ◽  
pp. 717-720
Author(s):  
Ki Hoon Moon ◽  
Sang Whan Han ◽  
Ji Eun Jung
Keyword(s):  
Moment Connections ◽  
Moment Capacity ◽  
Design Procedures ◽  
Reduced Beam Section ◽  
Moment Resisting ◽  
Current Design ◽  
Beam Section ◽  
The Moment ◽  
Rbs Connections ◽  
Experimental Researches

Reduced Beam Section (RBS) moment connections are developed for Special Moment Resisting Frames (SMRF). According to the beam web attachment the column flange RBS connections are classified into Reduced Beam Section with Bolted web connections (RBS-B), and the Reduced Beam Section with Welded web connections (RBS-W). Beam flanges are welded to the column. Regardless of different web attachment details in RBS-B and RBS-W connections current design procedures (FEMA 350) assumes that they could develop plastic moment of the beam gross section. In current design procedures, RBS-B connections should provide the sufficient strength that can reach the plastic moment capacity of the connected beam. However, some experimental researches reported that the beams in RBS-B connections fractured before the connection reached its plastic moment capacity. Such undesirable fracture shows that RBS-B connections have less strength than RBS-W connections. And if RBS-B connections designed in current design procedures, it might fail in a brittle manner and not satisfy SMRF due to undesirable fracture. Thus, this study develops a new set of equations for accurately computing the moment strength of RBS-B connections. The proposed strength equation accurately predicts connection moment capacity for RBS-B connections.

scholarly journals Performance of Retrofitted Self-Compacting Concrete-Filled Steel Tube Beams Using External Steel Plates

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Ahmed A. M. AL-Shaar ◽  
Mehmet Tolga Göğüş
Keyword(s):  
Theoretical Model ◽  
Flexural Strength ◽  
Energy Absorption ◽  
Failure Modes ◽  
Steel Tube ◽  
Steel Plates ◽  
Self Compacting Concrete ◽  
Moment Capacity ◽  
Concrete Filled Steel Tube ◽  
The Moment

Self-compacting concrete-filled steel tube (SCCFST) beams, similar to other structural members, necessitate retrofitting for many causes. However, research on SCCFST beams externally retrofitted by bolted steel plates has seldom been explored in the literature. This paper aims at experimentally investigating the retrofitting performance of square self-compacting concrete-filled steel tube (SCCFST) beams using bolted steel plates with three different retrofitting schemes including varied configurations and two different steel plate lengths under flexure. A total of 18 specimens which consist of 12 retrofitted SCCFST beams, three unretrofitted (control) SCCFST beams, and three hollow steel tubes were used. The flexural behaviour of the retrofitted SCCFST beams was examined regarding flexural strength, failure modes, and moment versus deflection curves, energy absorption, and ductility. Experimental results revealed that the implemented retrofitting schemes efficiently improve the moment carrying capacity and stiffness of the retrofitted SCCFST beams compared to the control beams. The increment in flexural strength ranged from 1% to 46%. Furthermore, the adopted retrofitting schemes were able to restore the energy absorption and ductility of the damaged beams in the range of 35% to 75% of the original beam ductility. Furthermore, a theoretical model was suggested to predict the moment capacity of the retrofitted SCCFST beams. The theoretical model results were in good agreement with the test results.

Flexural Tests on the H-Section Simple Beams with Local Buckling

2011 ◽  
Vol 105-107 ◽  
pp. 1677-1680
Author(s):  
Young Bong Kwon ◽  
Jin Hwan Cheung ◽  
Byung Seung Kong ◽  
Hwan Woo Lee ◽  
Kwang Kyu Choi
Keyword(s):  
Local Buckling ◽  
Bending Moment ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Moment Capacity ◽  
Flexural Members ◽  
Negative Effect ◽  
Large Width ◽  
The Moment ◽  
Flexural Tests

This paper describes a series of flexural tests conducted on the H-section beams fabricated from SM490 plate of thickness 0.6mm with nominal yield stress 315 MPa. Flexural members with large width-to-thickness ratios in the flanges or the web may undergo local buckling before lateral-torsional buckling. The local buckling has a negative effect on the moment capacity based on the lateral-torsional buckling. Simple bending moment capacity formulas for flexural members were calibrated to the test results to account for interaction between local buckling and lateral-torsional buckling. The ultimate flexural strengths predicted by the proposed formulas for direct strength method were compared with the AISC (2005) and Eurocode3 (2003). The comparison showed that the moment formulas proposed can predict conservatively the bending moment capacity of H-section flexural members with local buckling.

Experimental Investigation on Cold-formed Steel Beams under Pure Bending

2012 ◽  
pp. 13-20 ◽  
Author(s):  
Yeong Huei Lee ◽  
Yee Ling Lee ◽  
Cher Siang Tan
Keyword(s):  
Local Buckling ◽  
Bending Moment ◽  
Steel Beams ◽  
Pure Bending ◽  
Lateral Instability ◽  
Moment Capacity ◽  
British Standard ◽  
Cold Formed Steel ◽  
The Moment ◽  
Design Yield

This paper presents the flexural behaviour of cold-formed double lipped channels beams under pure bending action. Two channel sections are bolted back-to-back to form an I-shape structural beam member. A series of six experiment tests were carried out on beam specimens DC200 and DC250, each with 200 mm depth and 250 mm depth respectively. The thickness of beam section is 2 mm and the design yield strength is 350 N/mm2. All beams failed at local buckling at top-flange due to lateral instability of the cold-formed steel structural members. The moment resistance for DC200 is 17.87 kNm and DC250 is 31.53 kNm. The experimental results are compared to theoretical resistance prediction based on British Standard and Eurocode. The comparison showed that the experimental moment capacity is lower than the theoretical bending moment resistance but higher than theoretical buckling moment resistance from Eurocode. This showed that a better agreement is achieved between experimental data and Eurocode buckling moment resistance for cold-formed steel beam under pure bending. Kertas kerja ini membentangkan sifat lenturan rasuk keluli tergelek sejuk di bawah tindakan lenturan tulen. Dua channel dihimpunkan berkembar dan diperketatkan dengan bolt untuk membentuk rasuk struktur bentuk-I. Satu siri ujian lenturan telah dijalankan ke atas spesimen rasuk DC200 dan DC250, dengan kedalaman 200 mm dan 250 mm masing-masing. Ketebalan keratan rasuk adalah 2 mm dan kekuatan reka bentuk adalah 350 N/mm2. Semua rasuk gagal pada momen kilasan sisi di bahagian atas bebibir akibat ketakstabilan sisi anggota keluli tergelek sejuk. Rintangan momen bagi DC200 adalah 17.87 kNm dan DC250 adalah 31.53 kNm. Keputusan eksperimen dibanding dengan ramalan teori yang berdasarkan British Standard dan Eurocodes. Perbandingan tersebut menunjukkan bahawa rintangan momen lenturan eksperimen adalah lebih rendah daripada ramalan teori momen lenturan tetapi lebih tinggi daripada ramalan teori momen rintangan kilasan sisi mengikut Eurocode. Ini menunjukkan bahawa persetujuan baik dicapai di antara keputusan eksperimen dengan ramalan teori Eurocode momen rintangan kilasan sisi bagi rasuk keluli tergelek sejuk.

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