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عنوان انگلیسی مقاله:
On the improvement of buckling of pre twisted universal steel columns
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Steel structures are increasingly used in constructions as they proved to be more user- and environmental-friendly, more time effi- cient and less labor intensive than reinforced concrete. Steel is a recyclable material that can be reused when a building is demolished, leaving behind minimal waste, thus, preferable for sustainable construction. Furthermore, the uniformity and stability of steel as it does not creep or shrink with time unlike reinforced concrete makes it more desirable to be used in construction. However, one of the main disadvantages of a steel column is the susceptibility to buckle under compression before achieving the design strength. Buckling is a mode of failure that is mainly observed in compression members due to structural instability. The critical buckling load carried depends mainly on the slenderness of the member being investigated. For stocky members, a larger buckling load would be required to witness the deformed buckling mode. As a matter of fact, stocky compression members may fail mainly due to compressive yielding instead of buckling. Compressive yielding may occur if the stresses built within the compression members exceeded the yielding stress of the steel being used. However, for slender members, to be more specific, the stress just before buckling is below the proportional limit such that the member is still elastic [12]. Inducing a natural pretwist along the length of a column section makes the column have a different resistance at every point along its centroidal axis. It is well-known that a column usually buckles around the weak axis, but with pretwisting, the buckling mode of the column may no longer be perpendicular to the weak axis. Pretwisting is known to induce a coupling effect on the weak and strong flexural planes of a column. Hence, a pretwisted column in 3D-space has its strong flexural plane weakened and its weak flexural plane strengthened, leading to a net favorable effect on the buckling strength of the pretwisted column. Thus, the buckling load recorded with the first mode shape of the pretwisted column is relatively higher than that of the non-pretwisted column [15]. Another interesting definition of pretwisting would be; the rotation of the principal axes as a function of the centroidal axes of the cross-section along the column's length [3]. There are not enough studies on the topic of pretwisting and its effect on the buckling of structural compression members. However, the study of the nature of pretwisting and its applications has been introduced into the literature a long time ago. Celep [3] investigated the stability of an elastic cantilever column with a linear viscous internal damping system exposed to evenly distributed vertical and follower loads. Galerkins' technique was then applied to solve the prevailing differential equations of motion to determine the flexural deformation in both planes of a pretwisted slender column. Yang and Yau [16] studied the stability of pretwisted bars having assorted end torques. Two types of torques were investigated; quasi tangential and semitangential, on an originally straight bar but with an applied rotation angle. Tabarrok et al. [15] solved the equilibrium equations of buckling analysis of a pretwisted column utilizing the concept of total potential energy and the associated boundary conditions. Steinman et al. [14] studied the effect of pretwisting on statically determinate and indeterminate columns. To work out the buckling equations of a pretwisted column, the general stability equations applied for a spatial rod were used as a part of the derived differential equations. Exact numerical solutions to the controlling fourth-order differential equations were achieved through simple iterative approach. The input data to the
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کلمات کلیدی:
Buckling of Pretwisted Steel Columns https://dspace.aus.edu/xmlui/handle/11073/7775 by M Megahed - 2015 - Related articles A pretwisted column in 3D-space has its strong flexural plane weakened and its weak ... the elastic and inelastic behavior of one of the universal steel columns. ... that fixed-ended conditions ensured better buckling capacity improvement as ... Title Browse for On the improvement of buckling of pretwisted ... copac.jisc.ac.uk/browse?key...offset=0 On the improvement of buckling of pretwisted universal steel columns. ... On the improvement of church services, revision of the rubrics, and how to increase the ... Nonlinear Finite-Element Analysis of Buckling Capacity of Pretwisted ... ascelibrary.org/doi/full/10.1061/%28ASCE%29EM.1943-7889.0000528 This improvement is supported by the considerable increase in the critical buckling ... The experimental and numerical research on buckling of pretwisted columns ... then tested under compression using an Instron universal testing machine. Nonlinear Finite-Element Analysis of Buckling Capacity of Pretwisted ... ascelibrary.org/doi/abs/10.1061/(ASCE)EM.1943-7889.0000528 by FH Abed - 2012 - Cited by 3 - Related articles This improvement is supported by the considerable increase in the critical buckling loads of the bars, particularly at twisting angles ranged between 15 and 90°. Buckling of Pretwisted Steel Columns - Mai Megahed - Google Books https://books.google.com/books/about/Buckling_of_Pretwisted_Steel_Columns.html?id... A linear perturbation analysis was conducted for several universal column ... A number of pretwisted columns were then tested to examine the elastic and inelastic ... that fixed-ended conditions ensured better buckling capacity improvement as ... DYNAMICS AND BUCKLING OF THIN PRE-TWISTED BEAMS ... www.worldscientific.com › ... › Available Issues › Volume 10, Issue 05 by AYT LEUNG - 2010 - Cited by 6 - Related articles Free vibration and buckling of pre-twisted beams exhibit interesting coupling ... (2016) On the improvement of buckling of pretwisted universal steel columns.
