Experimental investigation of buckling response of pretwisted structural steel columns

Structures ◽  
2020 ◽  
Vol 27 ◽  
pp. 2232-2244
Author(s):  
Farid H. Abed ◽  
Mai Megahed
Keyword(s):  
Experimental Investigation ◽  
Structural Steel ◽  
Steel Columns

scholarly journals Buckling behavior of cold-formed steel columns at both ambient temperature and simulated fire conditions

Fire Research ◽  
2016 ◽  
Author(s):  
Hélder D. Craveiro ◽  
João Paulo C. Rodrigues ◽  
Luís M. Laím
Keyword(s):  
Experimental Investigation ◽  
Ambient Temperature ◽  
Cross Sections ◽  
Failure Modes ◽  
Steel Columns ◽  
Buckling Behavior ◽  
Wide Range ◽  
Cold Formed Steel ◽  
Simulated Fire ◽  
Fire Conditions

Cold-formed steel (CFS) profiles with a wide range of cross-section shapes are commonly used in building construction industry. Nowadays several cross-sections can be built using the available standard single sections (C, U, Σ, etc.), namely open built-up and closed built-up cross-sections. This paper reports an extensive experimental investigation on the behavior of single and built-up cold-formed steel columns at both ambient and simulated fire conditions considering the effect of restraint to thermal elongation. The buckling behavior, ultimate loads and failure modes, of different types of CFS columns at both ambient and simulated fire conditions with restraint to thermal elongation, are presented and compared. Regarding the buckling tests at ambient temperature it was observed that the use of built-up cross-sections ensures significantly higher values of buckling loads. Especially for the built-up cross-sections the failure modes were characterized by the interaction of individual buckling modes, namely flexural about the minor axis, distortional and local buckling. Regarding the fire tests, it is clear that the same levels of restraint used in the experimental investigation induce different rates in the generated restraining forces due to thermal elongation of the columns. Another conclusion that can be drawn from the results is that by increasing the level of restraint to thermal elongation the failure of the columns is controlled by the generated restraining forces, whereas for lower levels of restraint the temperature plays a more important role. Hence, higher levels of imposed restraint to thermal elongation will lead to higher values of generated restraining forces and eventually to lower values of critical temperature and time.

Improving buckling resistance of hollow structural steel columns strengthened with polymer-mortar

2019 ◽  
Vol 137 ◽  
pp. 515-526 ◽  
Author(s):  
Kh. M. El-Sayed ◽  
Ahmed S. Debaiky ◽  
Nader N. Khalil ◽  
Ibrahim M. El-Shenawy
Keyword(s):  
Structural Steel ◽  
Steel Columns ◽  
Buckling Resistance ◽  
Polymer Mortar

Adaption of active boundary conditions in structural fire testing

2019 ◽  
Vol 10 (4) ◽  
pp. 504-528
Author(s):  
Ramla Karim Qureshi ◽  
Negar Elhami-Khorasani ◽  
Thomas Gernay
Keyword(s):  
Boundary Conditions ◽  
Structural Steel ◽  
Test Specimen ◽  
Fire Test ◽  
Structural Elements ◽  
Fire Testing ◽  
Content Type ◽  
Steel Columns ◽  
History Of ◽  
Force Displacement

Purpose This paper aims to investigate the need for active boundary conditions during fire testing of structural elements, review existing studies on hybrid fire testing (HFT), a technique that would ensure updating of boundary conditions during a fire test, and propose a compensation scheme to mitigate instabilities in the hybrid testing procedure. Design/methodology/approach The paper focuses on structural steel columns and starts with a detailed literature review of steel column fire tests in the past few decades with varying axial and rotational end restraints. The review is followed with new results from comparative numerical analyses of structural steel columns with various end constraints. HFT is then discussed as a potential solution to be adapted for fire testing of structural elements. Challenges in contemporary HFT procedures are discussed, and application of stiffness updating approaches is demonstrated. Findings The reviewed studies indicate that axial and rotational restraints at the boundaries considerably influence the fire response of steel columns. Equivalent static spring technique for simulating effect of surrounding frame on an isolated column behavior does not depict accurate buckling and post-buckling response. Additionally, numerical models that simulate fire performance of a column situated in a full-frame do follow the trends observed in actual test results up until failure occurs, but these simulations do not necessarily capture post-failure performance accurately. HFT can be used to capture proper boundary conditions during testing of isolated elements, as well as correct failure modes. However, existing studies showed cases with instabilities during HFT. This paper demonstrates that a different stiffness updates calculated from the force-displacement response history of test specimen at elevated temperature can be used to resolve stability issues. Originality/value The paper has two contributions: it suggests that the provision of active boundary conditions is needed in structural fire testing, as equivalent static spring does not necessarily capture the effect of surrounding frame on an isolated element during a fire test, and it shows that force-displacement response history of test specimen during HFT can be used in the form of a stiffness update to ensure test stability.

Design of Locally Slender Structural Steel Columns

2014 ◽  
Vol 140 (4) ◽  
pp. 04013086 ◽  
Author(s):  
Mina Seif ◽  
Benjamin Schafer
Keyword(s):  
Structural Steel ◽  
Steel Columns

Experimental investigation of inelastic buckling of built-up steel columns

2012 ◽  
Vol 13 (3) ◽  
pp. 295-308 ◽  
Author(s):  
Rami A. Hawileh ◽  
Farid Abed ◽  
Adi S. Abu-Obeidah ◽  
Jamal A. Abdalla
Keyword(s):  
Experimental Investigation ◽  
Inelastic Buckling ◽  
Steel Columns

Experimental investigation on ferritic stainless steel columns in fire

2013 ◽  
Vol 62 ◽  
pp. 238-248 ◽  
Author(s):  
Nicola Tondini ◽  
Barbara Rossi ◽  
Jean-Marc Franssen
Keyword(s):  
Experimental Investigation ◽  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Steel Columns ◽  
In Fire
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