New Canadian provisions for the design of steel beam–columns

1990 ◽  
Vol 17 (6) ◽  
pp. 873-893 ◽  
Author(s):  
D. J. L. Kennedy ◽  
A. Picard ◽  
D. Beaulieu
Keyword(s):  
Traditional Method ◽  
Geometric Analysis ◽  
Steel Structures ◽  
Second Order ◽  
Effective Length ◽  
Order Effects ◽  
Limit States ◽  
Cross Sectional ◽  
Out Of Plane ◽  
Areas Of Concern

The beam–column interaction equations of the Canadian Standards Association Standard CAN3-S16.1-M84 "Steel structures for buildings — limit states design" are reviewed and areas of concern in the formulations are addressed. The interaction equations developed for the 1989 edition of the standard, CAN3-S16.1-M89 "Limit states design of steel structures," and the methods of dealing with the areas of concern in the previous standard are presented. The new standard requires that at least an approximate second-order geometric analysis be carried out. For frames dependent on the frame stiffness for lateral stability, no longer is the traditional method, using effective length factors greater than one, allowed. Unlike the current American Institute of Steel Construction "Load and resistance factor design'' (AISC LRFD) specification, two sets of interaction equations, one for in-plane member strength and the other for out-of-plane stability, are used. This results in considerably less unnecessary conservatism. In both sets of interaction equations, the component of the moment due to translation is increased by the second-order effects. The "double ω" problem has been resolved and the minimum sway effects for the gravity loading case have been increased substantially to guard against sidesway buckling. A design example using the new standard is given. By means of a series of analytical examples, the requirements of S16.1-M89 are compared with the traditional method of S16.1-M84. For frames with direct-acting bracing, S16.1-M89 gives interaction values about 1.15 times those of the previous standard with a coefficient of variation of 0.08, while for unbraced frames the corresponding values are 0.98 and 0.07. The S16.1-M89 values reflecting greater rigor in a number of areas are considered the more valid. The S16.1-M89 standard would give comparable results to the AISC LRFD specification for class 1 sections when out-of-plane behaviour governs. The latter specification does not specifically cover cross-sectional strength and in-plane behaviour as does S16.1-M89. Key words: beam–column, stability, strength, bending, compression, standards.

scholarly journals CONSIDERATIONS ON THE DIFFUSE SEISMICITY ASSUMPTION

2015 ◽  
Vol 12 (2) ◽  
Author(s):  
Jorge Daniel Riera ◽  
Ignacio Iturrioz
Keyword(s):  
Steel Structures ◽  
Direct Analysis ◽  
Second Order ◽  
Effective Length ◽  
Order Effects ◽  
Analysis Method ◽  
Order Analysis ◽  
3D Space ◽  
Effective Length Method ◽  
Diffuse Seismicity

Second-order effects were historically included by the effective length method (K concept). All the studies about that methodology have been developed in frame plane, with regular rectangular frames. The new way to include those effects is the use of second-order analysis, direct analysis method or alternative simplified options. This methodology was included in ANSI AISC360 in the 2005 version and in the 2010 version. As before, the studies already developed for DAM analysis are in plane. In this paper, the K concept is revisited by numerical analysis, and extended to the 3D space. Using models of symmetric and non-symmetric industrial steel structures in plane, 3D stability analyses were developed, and the results were compared with plane behavior. Several conclusions and recommendations were exposed, resulting from the analyzed models. Keywords: Second-order analyses, steel structures, irregular 3D frames.

scholarly journals Numerical analysis of reinforced concrete shear walls with rectangular cross section

2020 ◽  
Vol 13 (6) ◽  
Author(s):  
Maurício Castelo Branco de Noronha Campos ◽  
Paulo Marcelo Vieira Ribeiro ◽  
Romilde Almeida de Oliveira
Keyword(s):  
Reinforced Concrete ◽  
Numerical Analysis ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Concrete Columns ◽  
Second Order ◽  
Order Effects ◽  
Cross Sectional ◽  
Reinforced Concrete Columns ◽  
Mesh Model

abstract: This study addresses a numerical analysis of reinforced concrete columns in which the lengths are significantly larger than their widths with a rectangular cross section. Numerical simulations of 1,440 cases were performed, each case simulated with the single bar model, isolated bar model and mesh model, in addition, 3D model simulations were carried out. For the validation of 3D models and bar models, comparisons were made between the numerical simulation e experimental results of 24 reinforced concrete columns. Second order effects were analyzed on the vertical moment at the edge of the columns in which the lengths are significantly larger than the widths (localized second-order effects) and also the values of the horizontal moments along the cross sectional length in the mesh model. Influences of the main variables were observed influencing the behavior of the columns in which the lengths are significantly larger than their widths: the ratio between the cross sectional dimensions, the slenderness and the stresses (normal stress and bending moment around the axis of greatest inertia).

Second-order effects in URM walls subjected to compression and out-of-plane bending: From numerical evaluation to proposal of design procedures

2020 ◽  
Vol 209 ◽  
pp. 110130
Author(s):  
Marco Donà ◽  
Paolo Morandi ◽  
Massimiliano Minotto ◽  
Carlo Filippo Manzini ◽  
Francesca da Porto ◽  
...  
Keyword(s):  
Numerical Evaluation ◽  
Second Order ◽  
Order Effects ◽  
Design Procedures ◽  
Out Of Plane ◽  
Plane Bending ◽  
Second Order Effects

scholarly journals Alternative Design Procedure for RC-Braced Long Columns Based on New Moment Magnifiers Matrix

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Mohamed Farouk ◽  
Majed Alzara ◽  
A. Ehab ◽  
A. M. Yosri
Keyword(s):  
Flexural Rigidity ◽  
Design Procedure ◽  
Bending Moment ◽  
Order Effect ◽  
Second Order ◽  
Effective Length ◽  
Column Height ◽  
Order Effects ◽  
Order Analysis ◽  
Proposed Model

Based on modified methods for the results of first-order analysis of RC columns, different codes approximate the second-order effects by using equations focusing on the maximum additional moment through the column height. These equations did not refer to the additional moments between the column and the connected beam, only the effect of the connected beams is taken into consideration by dealing with the effective length of the column, not the total length. Moreover, these equations did not take into account the second-order effect, which is caused by axial force and the inverse moments due to beam restriction for the column ends. This paper presents a new moment magnifiers matrix for the additional moments at the connection between braced columns and the connected beams as a simplified computation that can be used in the design procedure. That is through an equation based on transforming the original long column in second-order analysis to an equivalent isolated column. The equivalent column was represented as an element restricted with rotational spring support at its ends, and it is subjected to lateral distributed loads that have the same influence of the second-order effect on the induced additional moments in the long column. The suggested equivalent column can be used to form the additional bending moment diagram, also to compute the additional deformations as well. Numerous factors were analyzed linearly by using the presented new moment magnifiers matrix and finite element method, and the results proved the efficiency of the proposed model. Although the presented suggested model is based on the isolated analysis of the long column, the effect of the additional moments in the adjacent long column can be considered by presented two suggestions to improve the model. Also, development was proceeded on the model by modifying the flexural rigidity (EI) which is recommended in ACI to appropriate the time of failure. The additional moment values of the developed model were close to the values calculated by the ACI equation.

scholarly journals Considerations about the determination of γz coefficient

2013 ◽  
Vol 6 (1) ◽  
pp. 75-100
Author(s):  
D. M. Oliveira ◽  
N. A. Silva ◽  
C. F. Bremer ◽  
H. Inoue
Keyword(s):  
Reinforced Concrete ◽  
Structural Model ◽  
Steel Structures ◽  
Second Order ◽  
Order Effects ◽  
Simplified Models ◽  
Simplified Analysis ◽  
Second Order Effects ◽  
Conservative Values

In this work, the γz coefficient, used to evaluate final second order effects in reinforced concrete structures, is studied. At the start, the influence of the structural model in determination of γz coefficient is evaluated. Next, a comparative analysis of γz and B2 coefficient, usually employed to evaluate second order effects in steel structures, is performed. In order to develop the study, several reinforced concrete buildings of medium height are analysed using ANSYS-9.0 [1] software. The results show that simplified analysis provide more conservative values of γz. It means that, for structures analysed by simplified models, large values of γz don't imply, necessarily, in significant second order effects. Furthermore, it was checked that γz can be determinated from B2 coefficients of each storey of the structures and that, for all the analysed buildings, the average values of the B2 coefficients are similar to γz.

The Practical Calculation Charts to Determine Column Effective Length of Framework and Bent Framework

2013 ◽  
Vol 351-352 ◽  
pp. 1052-1056
Author(s):  
Zhi Sheng ◽  
Dong Hua Zhou
Keyword(s):  
Axial Force ◽  
Steel Structures ◽  
Order Theory ◽  
Second Order ◽  
Effective Length ◽  
Practical Calculation ◽  
Column Length ◽  
Displacement Method ◽  
Special Cases ◽  
Stability Checking

Calculation of effective length of columns is key of stability checking in design, therefore some formulas and tables are given in Code for Design of Steel Structures (GB 50017-2010), which show some application Limitations. These formulas and tables are made based on assumptions for regular frames. For some special cases, such as existence of the large difference of the column axial force or column length among the framework columns, these formulas and tables are no longer applicable. The practical calculation charts are derived by authors by using the displacement method with the second-order theory, which can be used to quickly determine column effective length and show intuitive trends of the lengths.

scholarly journals Finite Element Analysis of Bolted T-Stubs Undergoing Large Displacement: A Preliminary Study

2018 ◽  
Vol 12 (1) ◽  
pp. 170-176 ◽  
Author(s):  
Anna C. Faralli ◽  
P.J. Tan ◽  
Massimo Latour ◽  
Gianvittorio Rizzano
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Steel Structures ◽  
Second Order ◽  
Large Displacement ◽  
Order Effects ◽  
Element Analysis ◽  
Parametric Investigation ◽  
Deformation Response ◽  
Second Order Effects

Background: In recent years, there have been increased interests by the steel structures community to characterise the large-deformation response of T-stubs to evaluate the deformation capacity of bolted joints. However, little information exists on the influence of second-order effects on the response of bolted T-stubs and, consequently, there are no existing guidelines on how to include these effects in de-sign. Objective: In this paper, we assess the influence of second-order effects in T-stubs bolted to a rigid support through a parametric investigation, using finite element analysis. Methods: Both material and geometrical non-linearities were considered since they are known to have a critical impact upon the performance of T-stubs. A benchmark model is first generated and validated and then used to carry out a parametric investigation. A method to assess the contributions of membrane forces to the overall deformation response of a T-stub is also proposed based on the introduction of a non-dimensional parameter Ψ. Results: The combination of geometric parameters that are most affected by second order effects, induced by large displacement, was identified. A direct correspondence was found between the extent of second order effects that has developed and the index Ψ: a higher index implies a greater influence by second order effects.

scholarly journals Evaluation of second order moments in reinforced concrete structures using the γz and B2 coefficients

2014 ◽  
Vol 7 (3) ◽  
pp. 329-348 ◽  
Author(s):  
D. M. Oliveira ◽  
N. A. Silva ◽  
P. M. Oliveira ◽  
C. C. Ribeiro
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Steel Structures ◽  
Second Order ◽  
Order Effects ◽  
Reinforced Concrete Structures ◽  
Ansys Software ◽  
First Order ◽  
Simplified Method ◽  
Second Order Effects

This paper presents an alternative to estimate the magnifier of first order moments to be applied on each storey of reinforced concrete structures, from the values obtained for the γz and B2 coefficients, used to evaluate second order effects in reinforced concrete structures and in steel structures, respectively. In order to develop the study, initially several reinforced concrete buildings of medium height are processed, in first order and in second order, using the ANSYS software. Next, γz, B2 and the increase in first order moments, when considering the second order effects along the height of the buildings, are calculated. Finally, from the results obtained, the magnifier of the first order moments, differentiated for each storey of the structure and calculated from both γz and B2 coefficients, is estimated and the efficiency of the simplified method of obtaining final moments using the magnifier proposed is evaluated.

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