analytic discussion of juncture behavior stocked with ...ashm-journal.com/test/vol2-6/78.pdf ·...

Applied mathematics in Engineering, Management and Technology 2 (6) 2014:608-621

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608

Abstract

After North rich (1994) earthquake, many ideas were offered about manner of

design and perform steel structures like juncture shaft with slotted web-reduced

flange. In this article, we discuss specification of this juncture for manners of shaft

with upper and beneath flange which juncture to pier and reduced section is

considered by slotting. Number and diameter of slots and lacking or existing flanges

is one of the parameters that are considered. For this, juncture suggested is analyzed

by cycling method and after drawing hysteresis method, it's beneath surface shows

scale of energy waste, is determined. In all models, non linear behaviors are

considered.

Keywords: Slotted Web-Reduced Flange, Correlated Flange, Cycling Loading, Wasted

Energy, Hysteresis Chart

1- Introduction

North rich earthquake at 1994 showed that moment steel system with welding junctures is in the rank of

formatting structure systems and have many disadvantages. After that event, it was showed that many buildings

exposed to fracture in juncture area, thus, many researches were performed for finding defects and restore

cycling behavior by moment's junctures.

In generally, researchers concentrated on two ideas. Some of them were following to removing situation of

plastic joint. Flange juncture with RBS and flange with SBW were formed based on second method.

In RBS method, with cutting flange section, flange is transmitted to proximity column. Lab studies were

performed on it and confirmed that this juncture can change non elastic shapes and obtains acceptable plastic

cycles.

One of the parameters which have many effects on fracture of flanges is plasticity of juncture stream. The

discussion showed that weak juncture stream confronts to great wear shapes which is derived from fracture

mode in juncture area. Since weak juncture stream has high ability for wasting energy but it is not advised to

use weak juncture stream. ( 5-4)

Also, although strong juncture stream reduces fracture potential but in other word, increases probable of

instability especially for juncture flange with RBS. According to lab discussions, it was recognized that medium

juncture stream has suitable performance ( 7-6)

RBS was cited as restored steel structure by SSDA of America in 1997 (8). This juncture is regarded as

combination of concreted junctures because in one section, body of flange is void and enhances juncture area by

wear plate. In this juncture, wear force is omitted and side- curvature event is minimized. Richard and et al 9,

confirmed its performance with experiments on this juncture.

Maleki and et al 10, discussed RBS and SBS in direct juncture for flange to column. They concluded that in this

manner, time performance is obtained when juncture stream is considered as weak.

As for said, in this article, RBS and SBW will be considered for Cloven juncture by upper and beneath flanges

when the flange is reduced by slotting.

2- Numerical Study on Juncture

For discussion effective parameters on juncture behavior, a numerical study was performed. As figure 1

displayed, models of one flange with IPE 300 and column with section HE200B were formed in Europe. Upper

and beneath flanges are designed by regulations of AISC-2010.(11)

Analytic Discussion of Juncture Behavior Stocked with Punctured

and Cloven Wing as well as Upper and Beneath Flange

Ali Ahmadi, Hamzeh Keakha, Mahmoodreza Tabatabai

Islamic Azad University Branch Of Zahedan

Applied mathematics in Engineering, Management and Technology 2014

A. Ahmadi et al

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Free ends of the shaft show changing shape of shaft in original form, beneath column is as joint and in upper

section, rolling base is considered.

The aim is obtainable by two steps, in first step; all models are analyzed by system and by 8 points, maxim

place of obeisance of elastic model is determined. This place shows crisis point.

In second step, juncture is located by cycling loading and is evaluated by Langer- Doran chart derived from

analysis and in all analysis, non linear behavior is considered.

In numerical models, number and diameter of slot, effect of correlation flange is considered too.

Figure 1- General model of Juncture

Details of models are as following:

2.1. Controlling Points

As displayed above, for discussion maximum points of obeisance of elastic model, 8 controls points are

considered in wing of flange. Figure 2 shows place of locating these points. And table 1 shows its

specifications.

Figure 2- Place of Controlling Points in Limited Element Model

Table 1- Specifications of controlling points for determining Elastic obeisance points

Specification

(mm)

No. of controlling

point

(0,0,150) 0

(100,0, 150) 1

(200,0, 150) 2

(220,0, 150) 3

(250,0, 150) 4

(280,0, 150) 5

(380,0, 150) 6

(480,0, 150) 7

2.2. Area leaned for flange


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In this area, slotting is sued for weakening wing of flange. Figure 3 shows details, similarly, the numbers are

shown in table 2.

Figure 3- Details of Slots in wings of flange

In this juncture, slots with diameters 1, 2, 3 cm have minimum 2D distances are evaluated. In this part, D shows

slots in wing of flange.

Table 2- scales of Slots mm

Beam a b C tf tw bf d

IPE 80 200 35 10.7 7.1 150 300

2.3. Upper and Beneath Flange

Dimensions of upper plates are determined as 200×170×15 and dimensions of beneath plates as 200×200×15.

2.4.Correlation Plates

Effect of correlation plates is discussed in seismic performance. In numerical models, thick of upper and

beneath plates are considered.

2.5.Incision Plate

Scale of incision plate is considered as 200×250×20 in all charts.

2.6.Details of Slotted

Plane of slotted with use of results from other researches was performed by seismic institute of America 8.

Based on it, in all models, width of slot to end of incision plate equals to 3/2 mm and from end of incision plate

to end section is 6/4 mm. Figure 4 shows end of slot with diameter 21 mm.

Its aim is to transit plastic from place of juncture to column and make a crisis place in remote place. Based on

researches, length of 280 cm is considered for this part. 10.


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Figure 4- Details of Juncture SBW

3- Analysis of limited Parts

For modeling and analysis on non linear models, Abacus commercial software is used. 12

3.1.Elements and Meshing

The samples are modeled by nodal element 4-shell as integrating reduced. Shell element has strength, wear,

curvature and axial resistance and its behavior shows bend and crest. This element cause to change its shape out

of page because of hardening by cycling. Shell element can change plasticity of materials, change of shapes and

great obeisance. This element has freedom degree 6: place change in straight x, y,z and turning around axels

x,y,z.

3.2.Modeling of Materials

Non linear behavior of materials is obtained by Kinematic- isotropic hardening with use of Ziegler. Figure 5

shows obeisance chart of consumable materials ASTM A527, elasticity model is MPa6101.2 and poison

coefficient is 0/3.

3.3.Loading Protocol

A sample loading are as control by place change and is acted to the end of beam. In analysis, all models in

loading 120 kn. In discussion cycling juncture, SAC is used. Figure 6.

In this manner, all models are loading to cycling angel 0.04. 13

Figure 6- Loading Protocol


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Figure 7- Tension – obeisance steel curvature

4- Nomenclature of Models

Table 4 shows summary of models. Model nomenclature is based on diameter and number of slots and lacking

correlation plates.

Table 4- Nomenclature of Samples analyzed

5- Analysis Results

Models described are recognized under loading and the results are compared by end of juncture with similar

specifications.

No. of slots Diameter of

slot (cm) Continuity plate Specimen

2 1 With continuity plate CPD1N2



2 1 Without continuity plate NCPD1N2















With continuity plate NORMAL FLANGE-CP

Without continuity plate NORMAL FLANGE-NCP


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Figure 7- Obeisance of controlling points in pressure beam for decorating slots with diameter 1 cm

6- Discussion of Elastic obeisance charts

After performing analysis, equal elastic obeisance is obtained in controlling points. Figure 7, 9, 11. Since we

can obtain place of elastic obeisance point, this area shows that plastic joint is located in this point and thus, it

can remove by juncture point because of welding joints.

Figure 7 shows results of models with number and diameter 1 cm with and without plates. As displayed, place

of more obeisance is located at all charts. This problem shows that place of plastic joint is on welding point.

As for figure 7, about effect of correlation plates, we can cite that if the more elastic obeisance is happened in

two points, but correlation points show their effective performance in points two and five. Difference is about

lacking use of more correlation plates.


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Figure 8. Hysteresis response with different decorations with diameter 1 cm

Figure 9 shows results for slots with diameter 2 cm. as for charts, we know that more obeisances are variable

between controls points like two and five. In this section, we see role of correlation plates in juncture function.

As for figures 9a, 9b, 9c, if we use continued plates, crisis area is transmitted to control point 5. Figures 10d, 10

e and 10f show that lacking use of continuity plates can locate maxim point on point two. Thus, continuity

plates influences on plastic joint positively.

Figure 11 shows charts from covered analysis from samples with diameter 3 cm. as for charts, it was seen that

with increasing slot diameter to 3 cm, place of occurrence locates in point 5. Also, the charts show that

continuity plates have a few effects on situation of maxim obeisance.


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Figure 9. Controlling points obeisance in pressure wing of beam for decorating different slots with diameter 2

cm

7- Discussion of hysteresis Charts

Hysteresis responses of numerical models are shown in figures 10, 18, 12. Beam anchor is calculated from

column level and rotation values are calculated from dividing place change by its length. Beneath level of the

charts show scales of energy wastes. Table 5 shows hysteresis curvatures.

As for results, the samples have stable hysteresis instead the manner of the slots with diameter 3 cm is used for

weakening it. As for charts 12a, 12b, 12c, it is displayed that with increasing drift to 0/04 radian, we see

weakening resistance and hardening.


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Figure 10. Juncture hysteresis response with different decorations of slots with diameter 2 cm

As for hysteresis charts and it's beneath level which show energy wastes, we can conclude that if we use

continuity plates, energy wasted is so more than before.

Figure 11. Controlling point obeisance in pressure wing for different decoration slots with diameter 3 cm


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Figure 12. Juncture hysteresis response with different decoration for slots with diameter 3 cm

CPD3N4


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NCPD3N2 NCPD3N3

NCPD3N4

8- Normal Juncture Charts

For better comprehension of effect of slots in wing, the models are considered with same elements in wing and

elastic obeisance charts are obtained. Figures 13 and 14 show the charts obtained from analysis. As displayed,

although hysteresis charts show stable behavior but place of obeisance occurrence is on place of juncture of

beam to column.

Figure 13. Controlling point obeisance in pressure wing of beam with current juncture

Normal connection WCP


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Normal Connection WOCP

Figure 14. Hysteresis Response for current beam

Normal Connection WCP

Normal Connection WOCP

The results are as summary on table 5.


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Table 5. General Results for sample analysis

Equal controlling point for more

obeisance elastic

More Elastic Equal

Obeisance E(KN.m) Specimen

2 0.00281402 20.793 CPD1N2

2 0.00249142 20.782 CPD1N3

2 0.00269419 20.711 CPD1N4

2 0.00271735 19.101 NCPD1N2

2 0.00251738 19.015 NCPD1N3

2 0.00261742 18.764 NCPD1N4

5 0.00262733 20.744 CPD2N2

5 0.00271823 20.705 CPD2N3

5 0.00276894 20.691 CPD2N4

2 0.00261784 18.826 NCPD2N2

2 0.00243777 18.97 NCPD2N3

2 0.00231456 18.934 NCPD2N4

5 0.00251281 18.951 CPD3N2

5 0.00261753 18.855 CPD3N3

5 0.00261767 19.019 CPD3N4

5 0.00228984 18.82 NCPD3N2

5 0.00231888 18.713 NCPD3N3

5 0.00259859 18.645 NCPD3N4

2 0.00281373 20.677 NORMAL

FLANGE-CP

2 0.00271691 18.93 NORMAL

FLANGE-NCP

9.Concluding

One of methods for amending junctures applied is to use momentum SWRF which is derived from combination

of RBS and SBW. One of the weakest points is to cut wing beam. Because, this case can weaken concentration

tension on point and also, needs to professional workers for it. For removing these problems, it is suggested that

to use slots for weakening wing beam and for reaching to it, juncture behavior is evaluated by analysis and

cycling loading.

As for results obtained from analysis, it is seen that slots with diameter 1 cm are not suitable, because place of

obeisance is on place of juncture beam that can make dangerous area. Slots with diameter 2 cm is acceptable

when use as well as continuity plates, since lacking use of continuity plates, we see elastic equal in juncture of

beam to column.

Similarly for samples with diameter 3 cm, the result for elastic obeisance is better and continuity plates don’t

influence on crisis area.

In other word, hysteresis behavior show that slots with diameter 3 cm have downfall pressure in change places

with 0.04 rad, whereas, hysteresis for samples without plates is stable.

Although, hysteresis behavior for slotted models with diameter 3 cm is stable without continuity plates but it is

pointed that few energy waste is sensible for slotted samples with diameter 2 cm.

As for said contents, optimized decoration for weakening wing beam in SBW is to perform slots with diameter

2 cm with continuity plates.

References

[1] Engelhardt MD, Winneberger T, Zekany AJ, Potyraj TJ. The dogbone connection: Part II. Modern Steel Construction:

46-55, 1996.

[2] Engelhardt MD, Winneberger T, Zekany AJ, Potyraj TJ. Experimental investigation of dogbone moment connection.

Eng AISC; Forth Quarter: 128-38, 1998.


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[3] Yu QS, Gilton C, Uang CM. Cyclic response of RBS moment connections: Loading sequence and lateral bracing

effects. Report no. SSRP 99-13. San Diego (CA): Department of Structural Engineering, University of California; 1999.

[4] Krawinkler A. Shear in beam-column joints in seismic design of steel frames. Eng J ASCE; Third Quarter: 82-91,

1978.

[5] Popov EP. Panel zone flexibility in seismic moment joints. In: Chen WF, editor. Joint flexibility in steel frames.

London: Elsevier Applied Science; 1987.

[6] Tsai KC, Chen WZ. Seismic response of steel reduced beam section to weak panel zone moment joints. In:

Mazzolani FM, tremblay R, editors. Behaviour of steel structures in seismic areas. Rotterdam: Balkema; 2002

[7] jones SL, Fry GT, Engelhardt MD. Experimental evaluation of cyclically loaded reduced beam section moment

connections. J Struct Eng ASCE; 128(4): 441-51, 2002

[8] Seismic Structural Design Associates (SSDA). Beam slot connection design manual. Laguna Niguel, California; 1998.

[9] Richard RM, Allen CJ, Partridge JE. Proprietary slotted beam connection design. Modern Steel Construction: 28-33,

1997.

[10] Maleki Sh, Tabbakhha M. Numerical study of slotted-web-reduced-flange moment connection. Journal of

Constructional Steel Research; volumn 65, Issu 7: 1-7, 2012.

[11] American Institute of Steel Construction (ANSI/AISC 358-10)

[12] ABAQUS Version 6.12 Documentation. ABAQUS Inc. 2012.

[13] SAC. Seismic design criteria for new moment-resisting steel frame construction. Report no. FEMA 350. SAC Joint

venture. Sacramento, CA: 2000.

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