CC BY
2
yflK 691.714.124
doi: 10.55287/22275398_2023_1_88
COMPARISON THE DESIGN GUIDELINES FOR THE STEEL TRUSS ELEMENTS USING AISC AND EUROCODE3
M. A. A. Obeid S. Qasemi A. Chakraborty F. S. Akoev D. L. Rodriguez
Peoples' Friendship University of Russia (RUDN University), Moscow
Abstract
The aim of the research-to illustrate the comparative design procedures for tension members & compression member's usage of two exclusive International diagram codes. the American Institute of Steel Construction (AISC), the European Code (EC3). It focuses on the resistance capacity of steel members individuals subjected to external loads, internal loads and self-weight etc. Such as tension, compression and flexure. It compares the method of all codes that discover their similarities and differences. The comparison studies the behaviour of the single angle & W section under the load with two different zones, tensile yield and rupture strength, resistance to pressure. The outcomes are introduced graphically in specific approaches such as strength curves, Moment capacity, lateral bracing length and normalized graphs. The comparative finds out about suggests that the resistance capacity. For compression member, specifications have higher capacity and economical approach. For Tensile yield strength, EC3 gives higher capacity for elastic region and AISC(LFRD) gives higher capacities for inelastic region for Tensile rupture strength.
Introduction
Usually, tension members and compression members are made of hot-rolled profiles, usually angle or channel profiles: in other cases, cold-formed profiles can be conveniently used. Load carrying capacity of tension members [1, 2] is primarily governed by the following factors:
• Residual stress distribution caused by manufacturing process.
• Component end connection detail.
The load-bearing capacity of the connection point depends on the effective area. When the power transmission mechanism is analyzed in terms of the centroid of the cross-section, the effective (or net) area is
The Keywords
tension member, compression member, design curve, flexural members, lateral-torsional buckling
Date of receipt in edition
11.12.2022
Date of acceptance for printing
20.01.2023
equal to the total area for the corresponding reduction in pore pressure. For staggered holes, the effective area shall be assumed to be the minimum between the estimated effective area associated with the straight portion and the effective area associated with the appropriate polyline through the hole [3]. This paper, illustrates a comparison of different design specifications for the design of Steel frames elements and those are AISC, EC3 as per the studies by different authors [4]. In the United States, specification for structural steel buildings was developed by the AISC which utilizes both load and resistance factor design (LRFD) and allowable strength design (ASD) formats in Europe, "Design of Steel Structures, EN 1993 (EC3)" was developed by the European Committee for Standardization.
Methods
Steel tension members
Design according to the European method:
Members in tension subjected to the design axial force NEd must satisfy the following condition at every section, in accordance with European provisions:
NEd * N
t, Rd
(1)
It should be assumed that the design tensile strength, Nt Rd of the cross-section is the minimum between the plastic resistance of the total cross-section, Npl , Rd , and the net cross-section resistance in contact correspondence [5, 6],
N Rd , which is, Respectively, it is defined as:
Npl , Rd = A.fy / YM0 Npl , Rd = °.9.Anet.fu / YM2
(2)
(3)
where A and Anet represent the gross area and the net area in correspondence of the holes, respectively, and fy and fu are the yield and ultimate strength, respectively, with Ymo and Ym2 representing the material partial safety factors.
It should be noted that the term Npl Rd is associated with ductile failure due to yield strength achievement, while Nu Rd is associated with brittle failure in the conductive section. In the case of seismic loads, a well-established amplitude design approach requires ductile behaviour of the member under tension (eg, N Npl Rd ), which can be ensured if:
u, Rd
>
Anet * fy / fu.YM2 / Ym)A / °.9
(4)
Referring to single or double angles connected via a single leg, the effective area to be considered for evaluating the tensile load capacity [7], assuming that the force transmission mechanism is only attached to one leg.
When a single angle is used, reference must be made to the standard mentioned in EN 1993-1-8: a single tension angle connected by a single row of bolts in a single leg can be treated as experimentally loaded via an effective grating section having the final design resistance.
CD
< □
£ ® 0£ m O <U
ca .c < ^
< w
X (U
° .E
< "5 , -a
^ a
w E
< .5?
■ -S
w T3 D .c
ih +J UJ c
O w
3 '»I
< (C
. a
<« E
N„ Rd , they are defined as:
• with one bolt
Nu , Rd = 2.0.(e2 - 0.5do ).t.fu / Ym2 (5)
• with two bolts
Nu , Rd = p2Anet . fu / YM2 (6)
• with three or more bolts
Nu , Rd = p3 .Anet . fu / YM2 (7)
where e2 is the distance from the axis of the hole to the outer edge of the element in the direction orthogonal to the force, do is the diameter of the hole, terms and ^3 are reduction factors depending on the pitch p^
Design according to the US method
LRDF approach:
The design of the tensile member in accordance with the American Provisions for Load Factor and Strength Design [8] (LRFD) meets the requirements of the AISC specification when the design tensile strength ^>t Pn of each structural component equals or exceeds the required tensile strength Pu determined on the basis of the LRFD load groups, that is:
Pu * «> * Pn (8)
where is the tensile resistance factor and Pn represents the nominal tensile strength.
ASD approach:
A design in accordance with the allowable strength design (ASD) requirements meets the requirements of the AISC specification when the allowable tensile strength Pn / H t of each structural component equals or exceeds the required tensile strength Pa determined on the basis of ASD load groups, i. e.:
Pa * Pn / H t (9)
where H t is the tensile safety factor and Pn represents the nominal tensile strength.
Pn has to be determined as the minimum value obtained according to the limit states of tensile yielding and tensile rupture
Pn = min {Pn , y ; Pn , u } (10)
1) For tensile yielding in the member gross section (ductile failure), the resistance is defined as:
P = f A
n , y y g
(11)
where fy is the specified minimum yield stress and Ag is the gross area of the member. In this case H t = 1.67 and = 0 90.
2) For tensile rupture in the member net section (brittle failure), the resistance is defined as:
P = f A
n , u u' e
(12)
where fu is the specified minimum tensile strength and Ae is the effective net area of the member. In this case H t = 2.00 and = 0 75.
3) For tension members where the tension load is transmitted to some but not all of the cross sectional elements by fasteners or welds:
Ae = AnU
(13)
where U is the shear lag factor.
Steel compression members
A member is considered to be compressed when subjected to an axial force applied at its centroid or if it is loaded by an eccentric axial force with a very small eccentricity. In accordance with the current design practice, eccentricity is considered to be sufficiently small when it is less than 1/1000 of the member length.
Design according to the European method:
Strength design for a compression member subjected to a centric axial force NEd at a given cross-section is performed [9] by comparing the demand to the axial resistance capacity Nb Rd , that is:
NEd ^ Nb , Rd
(14)
The design compressive strength, Nc,Rd, is defined as a function of the cross-sectional class, identified as: • cross-sections of class 1, 2 or 3:
Nb , Rd = x.Afv / Y
-y / JM1
(15)
cross-sections of class 4:
N
b , Rd = x.Aefffy / YM1
(16)
where A is the gross cross-sectional area, Aeff is the effective cross-sectional area (accounting for local buckling phenomena), fy is the yielding strength of the material [10], X is a reduction factor and Ym1 is the partial safety factor.
More specifically, coefficient X is the reduction factor for the appropriate buckling mode calculated as follows:
z
M
O -l M
D CD
< □
£ ® 0£ m O <U
ca .c < ^
< w
X (U
° .E
< 7u , -a
^ a
w E
< .5? ■
w T3
D .c
ih +J IU c
O w
3 '»I
< (C
. a
< E
X = 1/9 + V(92 - X2) withx < 1 (17)
in which the coefficient 9 is defined as:
9 = 0.5.[1 + a(X - 0.2) + X2]
• cross-sections of class 1, 2 or 3:
cross-sections of class 4:
(18)
(19)
(20)
in which Ncr is the elastic critical load for the appropriate buckling mode (flexural, torsional or flexural-torsional).
In which Xl represents the proportionality slenderness and indicated with Xp , Lcr is the effective length of the member under consideration, A and Aeff are the gross cross-section and effective area, respectively, and i is the radius of gyration of the cross-section.
Design according to US method:
For a compression member in absence of imperfections and assuming a linear-elastic constitutive law(Euler column) , a worth of the axial force could be found to trigger element instability, titled elastic critical load [11], Ncr .This phenomenon can take place flexural, torsion or with a mixture of a flexural and a torsional behavior, cross-section in the undeformed and in the deformed situation, respectively.
LRFD approach
Design according to the provisions for load and resistance factor design (LRFD) satisfies the requirements of AISC Specification when the design compressive strength ^cPn of each structural component equals or exceeds the required compressive strength [12, 13] Pu determined on the basis of the LRFD load combinations Design has to be performed in accordance with the following equation:
Pu < 4>c?n (21)
where is the compressive resistance factor (^>c = 0 90).
ASD approach
Design according to the provisions for allowable strength design (ASD) satisfies the requirements of AISC Specification when the allowable compressive strength [14, 15] Pn / Hc of each structural component equals or exceeds the required compressive strength Pa determined on the basis of the ASD load combinations Design has to be performed in accordance with the following equation:
Pa < Pn "c (22)
where Hc is the compressive safety factor (Hc = 1.67)
The nominal compressive strength Pn is determined as:
P = F ,A
n cr g
(23)
The critical stress Fcr is referred to the limit state of flexural buckling as well as for torsional and flexural-torsional buckling. AISC Specifications give different expressions for Fcr .
Results and discussions
The Design tension resistance of single angle at a tensile yield strength in the EC3 is given more than 10% safe of the AISC at LRFD and 40%, safe compared to ASD as shown in the figure 1. This mean that the ASD is less secure than the others methods.
Fig. 1. Tensile yield strength comparison between AISC and EuroCode3
z
M
O _l M
D CD
Fig. 2. Tensile rupture strength comparison between AISC and EuroCode3
< □
t 8
T **
0£ m
O d)
CO .c
< ^
< tfl
X (U
° .E
< 7u , -a
5? '5
^ a
w E
< .5? ■
w T3
O .C
ih +J
IU c
O w
3 '»I
< (C
. a
< E
Through the previous figure 2, it can be seen that when calculating tensile rupture strength, there is a convergence in the values between the American code and the European code on the ASD method, and a noticeable difference in the LFRD method. This means that in the LFRD method, more safety coefficients are used than the other methods, and this reflects in the cost of the design and the type of materials that can be used in the project.
the available column strength
5000
4500 4000 3500 3000 2500 2000 1500 lOOO 500 O
Nb,Rd - — ■ LFRD ASP
Fig. 3. Resistance to pressure comparison between AISC and EuroCode3
It is also shown through the following drawing that the higher the section height, the more a difference appears between the methods of calculating resistance to pressure, while the lower the section height appears, there is a convergence in the values in the American code, whether in the LFRD or ASD method, and it can be said that in the European code many safety coefficients are used In contrast to the American code, which depends on a small number of transactions, and this means that when using the American code in calculating the pressure elements, there will be less cost and more economical, which will be reflected in the total cost of the entire project.
References
1. American Institute of Steel Construction 2011 Steel Construction Manual 13th Edition p. 2245.
2. AAVV (2005) Steel Designer's Manual, (eds B. Davison and G.W. Owens), The Steel Construction Institute, Blackwell Science Ltd, Oxford, UK.
3. AAVV-ECCS (2006) Rules for Member Stability in EN 1993-1-1, Background Documentation and Design Guidelines, European Convention for Constructional Steelwork.
4. AAVV-ECCS n. 123 (2008), Worked Examples According to EN 1993-1-3 Eurocode 3, Part 1-3, European Convention for Constructional Steelwork.
5. Ballio, G. and Mazzolani, F. M. (1983) Theory and Design of Steel Structuers, Taylor & Francis.
6. Chen, W. F. (ed.) (1997) Handbook of Structural Engineering, CRC Press.
7. Dowling, P. J., Harding, J. E. and Bjorhovde, R. (eds) (1992) Constructional Steel Design: an International Guide, Elsevier Applied Science.
8. Faella, C., Piluso V. and Rizzano, G. (2000), Structural Steel Semirigid Connections, CRC Press.
9. Gardner, L. and Nethercot, D.A. (2005) Designers' Guide to EN 1993-1-1 — Eurocode 3: Design of Steel Structures General Rules and Rules for Buildings, Thomas Telford.
10. Ghersi, A., Landolofo, R. and Mazzolani, F. M. (2002) Design of Metallic Cold-Formed Thin-Walled Members, Spon Press.
11. Johansson, B., Maquoi, R., Sedlacek, G., Müller, C., and Beg D. (2007) Commentary and Worked Examples to EN 1993-1-5. Plated Structural Elements. Joint Report Prepared under the JRC — ECCS cooperation agreement for the evolution of Eurocode 3 (programme of CEN / TC 250).
12. Rodhes, J. (1991) Design of Cold Formed Steel Members, Elsevier Applied Science.
13. .Sedlacek, G., Feldmann, M., Kühn, B., Tschickardt, D., Höhler, S., Müller, C., Hensen, W., U Stranghöner, N., Dahl, W., Langenberg, P., Münstermann, S., Brozetti, J., Raoul, J., Pope, R., and Bijlaard, F. ^ (1993) Commentary and Worked Examples to EN 1993-1-10. Material Toughness and Through Thickness Q Properties and other Toughness Oriented Rules in EN 1993. Joint Report Prepared under the JRC — ECCS M cooperation agreement for the evolution of Eurocode 3 (programme of CEN/TC 250).
14. Simoes da Silva, L., Simoes, R., and Gervasio, H. (2010) Design of Steel Structure- Eurocode 3: Design of Steel Structures — Part 1-1 — General Rules and Rules for Building, Ernst Sohn, A Wiley Company.
15. Trahair, N. S., Bradford, M. A., Nethercot, D. A. and Gardner, L. (2007) The Behaviour and Design of Steel Structures to EC3, Taylor & Francis Group.
CD
СРАВНИТЕ РЕКОМЕНДАЦИИ ПО ПРОЕКТИРОВАНИЮ СТАЛЬНЫХ ФЕРМЕННЫХ ЭЛЕМЕНТОВ С ИСПОЛЬЗОВАНИЕМ AISC И EUROCODE3
М. А. А. Обейд Ш. Касеми А. Чакраборти Ф. Ш. Акоев Д. Л. Родригес
Российский университет дружбы народов (РУДН), г. Москва
Аннотация
Цель исследования—проиллюстрировать сравнительные процедуры проектирования элементов натяжения и сжатия с использованием двух эксклюзивных международных кодов диаграмм. Американский институт стальных конструкций (АКС), Европейский кодекс (ЕС3). Он
Ключевые слова
растянутый элемент, сжатый элемент, расчетная кривая, изгибные элементы, потеря устойчивости при кручении
J и
7г и < □
f: S
0£ (Л
О щ
СО л < ^
< и X щ и С
< ш , -а
55 ^ га
w Е
< .5?
ф И ■
<л ъ
О л
IH -и
ш с
£ °
О <л
< га . а
< Е Z и
фокусируется на сопротивляемости отдельных элементов стального Дата поступления в редакцию элемента внешним нагрузкам, внутренним нагрузкам, собственному 11.12.2022 весу и т. д. Такие, как растяжение, сжатие и изгиб. В нем сравнивает- Дата принятия к печати ся метод всех кодов, которые обнаруживают их сходства и различия. 20.01.2023 В ходе сравнения изучается поведение одиночного углового сечения под нагрузкой с двумя различными зонами, предел текучести при растяжении и разрыве, устойчивость к давлению. Результаты представлены графически в конкретных подходах, таких как кривые прочности, моментная мощность, длина бокового крепления и нормализованные графики. Сравнительный анализ свидетельствует о том, что емкость сопротивления. Для компрессионного элемента технические характеристики имеют более высокую производительность и экономичный подход. Что касается предела текучести при растяжении, ЕС3 обеспечивает более высокую пропускную способность для эластичной области, а АКС (ЪРЯБ) обеспечивает более высокую пропускную способность для неупругой области для прочности на разрыв при растяжении.
Ссылка для цитирования:
M. A. A. Obeid, S. Qasemi, A. Chakraborty, F. S. Akoev, D. L. Rodriguez. Comparison the design guidelines for the steel truss elements using AISC and EuroCode3. — Системные технологии. — 2023. — № 1 (46). — С. 88 - 96.
