module c design of steel members and joints

8/12/2019 Module c Design of Steel Members and Joints

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European Erasmus Mundus Master Course

Sustainable Constructionsunder Natural Hazards and Catastrophic Events520121-1-2011-1-CZ-ERA MUNDUS-EMMC

Conceptual Design of Buildings(Course unit code 1C2)

Module CDesign of Steel Members and Joints

J.P. Jaspart (University of Lige)


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L21 Simple joints and hollow section joints. Behaviour and design of column bases.

European Erasmus Mundus

Master Course

Sustainable Constructions

under Natural Hazards

and Catastrophic Events

Conceptual Designof Buildings

2

Module C Design of Steel Members

and Joints

List of contents

Simple joints

Examples

Hollow section

joints

Design of column

bases

Examples

Simple joints are assumed to transfer no bending moments and should be

designed accordingly.

Main typologies: end plate of partial depth; fin plate or web cleats.

- Beyond the EC3-1-8 rules, some additional requirements are provided in the publication

n 126 of ECCS: European Recommendations for the Design of Simple Joints in Steel

Structures. These type of joints will be included in the Manual Design of Joints in Steel

and Composite Structures, ECCS (J.P. Jaspart and K. Weynand).


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under Natural Hazards



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and Joints

A simple joint is designed to resist to axial and shear forces only. As a

consequence, the development of bending moment may be potentially

unsafe, in particular if the joint presents a reduced ductility.

The "hinge assumption" is safe if, beyond the joint resistance checks, the

two following requirements are fulfilled:

- the joint possesses a sufficient rotation capacity (to not develop

bending moment);

- the joint possesses a sufficient ductility (to allow redistribution of

forces by the several joint components).

With the aim to permit a rotation

without increasing too much thebending moment which develops into

the joint, the contact between the lower

beam flange and the supporting

member has to be strictly avoided.

List of contents

Simple joints

Examples

Hollow section

joints

Design of column

bases

Examples


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and Joints

The design of a simple joint involves the verification of the resistance

(VEd VRd), the condition available required and some additional ductility

requirements, which depend of joint configuration.

Notations fin plate joint

List of contents

Simple joints

Examples

Hollow section

jointsDesign of column

bases

Examples


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and Joints

EXAMPLE 1

Check the safety of the following simple joint submitted to a vertical shear

force VEd = 100 kN (complete resolution may be find in P126 of ECCS).VEd = 100 kN

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

EXAMPLE 1

Requirements for sufficient rotatation capacity

(1) hp db

(2) available > required

2

ep2

h h2

hgz

""available

e

p

h

2

e

p2

h

available

h2

h

gzarctg

h

2

hgz

zarcsin

where:

if z >

if not:

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

EXAMPLE 1

Requirements for sufficient rotatation capacity

List of contents

Simple joints

Examples

Hollow section


bases

Examples

Requirements to avoid

premature weld failure

ypw M 2 p

up M 0

f

a tf2


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and Joints

EXAMPLE 1

Joint shear resistance

1. Bolts in shear

2. Fin plate in bearing

3. Gross section of the fin plate in shear

4. Net section of the fin plate in shear5. Shear block of the fin plate

6. Fin plate in bending

7. Buckling of the fin plate

8. Beam web in bearing

9. Gross section of the beam web in shear

10. Net section of the beam web in shear

11. Shear block of the beam web

Rdi

11

1i

Rd VV min

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

Requirements to allow a plastic redistribution of internal forces

(ductility)

Shear resistance of the joint: VRd= 146.18 kN

Failure Mode: Beam web in bearing

(= VRd8)

(the other is for fin plate)

(If VRd = VRd3, VRd4, VRd5, VRd6, VRd9,

VRd10, VRd11

then VRd1>min (VRd2, VRd8))

List of contents

Simple joints

Examples

Hollow section


bases

Examples

EXAMPLE 1


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and Joints

The Eurocode 3, part 1.8 provides actual design rules for joints between

both open and hollow sections.

Design rules forhollow section joints (semi-empirical rules calibrated withexperimental tests) were developed by CIDECT (International Committee

for Research and Technical Support for Hollow Section Structures).

These type of joints are used essentially in trussed structures or lattice

girders.

List of contents

Simple joints

Examples

Hollow section

jo intsDesign of column

bases

Examples


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and Joints

a) Chord face failure

b) Chord web failure

c) Chord shear failure

d) Punching shear failure

e) Brace failure

f) Local buckling failure

Failure modes

List of contents

Simple joints

Examples

Hollow section

jo intsDesign of column

bases

Examples


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and Joints

Current typologies of column bases

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

Anchor bolts may be manufactured in

accordance with one of the followingstandards:

EN 10025 (current mild steel),

EN 10080 (reinforcing bars),

EN ISO 898 orEN 14399 (bolts).

Anchor bolts

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

i) Concrete in compression + base plate in bending due to compression -T-stub in compression (clause 6.2.5 - EC3-1-8 and EC2-1-1);

ii) Tension resistance (clause 6.2.6.12 of EC3-1-8) and lifting of anchor bolts

(EC2-1-1);

iii) Shear resistance of anchor bolts (clause 6.2.2 of EC3-1-8), includingconcrete crushing (EC2-1-1);

iv) Friction resistance between base plate and concrete foundation (clause6.2.2 of EC3-1-8).

Behaviour and active components

Steel components (column and base plate) similar to beam-column joint with end-plate

Additional components associated withconcrete foundation:

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

i) Concrete in compression + base plate in bending due to compression - T-stub incompression (6.2.5 - EC3-1-8 and EC2-1-1).

c= t[fy/ (3 fjdM0)]0.5

FC,Rd= fjdbefflefffjd

c

2

2cjd

f

EdM

6

2t

y

f

RdM

Characterization of components associated with concrete foundation

fjd

- Design bearing strength of concrete.

Uniform pressure

in concrete fjd

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints


fcd - Design value of concrete compressive strength;

fck - Characteristic compressive cylinder strength of concrete at 28 days.

C

ckcdf

cdjj d

- The design bearing strength (fjd) of concrete may conservatively be taken as:

- A more accurate value of fjd should be obtained in accordance with clause 6.7 ofEC2-1-1, as specified in clause 6.2.5 (7) of EC3-1-8.

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

Anchor bolts with threads non-

conform with EN 1090

Minimum of:85.09.0

2

. M

subRdt

AfF

2

.

6.0

M

upm

Rdp

ftdB

and resistance to lifting of anchor bolts:

- bond resistance (8.4 - EC2-1-1) anchorage by hooks;

- pull-out failure (9.2.3 - CEB) headed anchors;

- concrete cone failure (9.2.4 - CEB);

- splitting failure (9.2.5 - CEB).

ii) Tension resistance (6.2.6.12 of EC3-1-8) and lifting of anchor bolts (EC2-1-1)


List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

2

1.

M

ubRdb

tdfkF

2

.,2

M

subbcRdvb

AfF

85.06.0

2

.

M

subRdv

AfF

fyb- yield strength of the anchor bolt, within 235 N/mm2 fyb 640 N/mm

2.

or

and crushing resistance of concrete:

- concrete pry-out failure (9.3.3 - CEB)

- concrete edge failure (9.3.4 - CEB);

Fv,Ed

v

NEd

- shear resistance with lever arm (9.3.2.2 - CEB)

ybbc f0003.044.0

2

.

6.0

M

ubRdv

AfF

iii) Shear resistance of anchor bolts (6.2.2 of EC3-1-8), including concretecrushing (EC2-1-1)

Minimum of:

Anchor bolts with threadsnon-conform with EN 1090


List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

The design resistanceNj,Rd of a column base plate under axial compression may

be determined by adding the individual design resistance FC,Rd of the 3 T-stubs(not overlapping) shown in the following figure.

f,Rd = Cf,d Nc,Ed

Cf,d - the coefficient of friction between base plate and grout layer (=0.20 for sand-

cement mortar and should be obtained by testing in accordance with Annex D of

EN 1990 for other types).

Nc,Ed - the design value of the normal compressive force in the column.

iv) Friction resistance between base plate and concrete foundation (6.2.2 ofEC3-1-8)

Compression resistance


List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

Design tension and compression forces and the lever arms are defined as following:

FT,l,Rd - design tension resistance on the left side;FT,r,Rd - design tension resistance on the right side;

FC,l,Rd - design compression resistance on the left side;

FC,r,Rd - design compression resistance on the right side.

Resistance to compression + bending moment

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

The design moment resistantMj,Rd (combined with Nj,Ed) should be determined inaccordance with the following table (neglecting T-stub 2):

Resistance to compression + bending moment

Rotational stiffness stiffness coefficients

are defined in Table 6.11

and evaluated in

accordance with Table

6.12 of EC3-1-8.

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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and Joints

EXAMPLE 2

Design the joint of a column HEB 260 (S 275) to a concrete foundation (C25/30)

through a base-plate connected to the foundation by anchor bolts, under the

following load combinations:

a)Axial compression NEd = 800 kN;

b) Axial compression NEd = 800 kN combined with a bending momentMEd = 150 kNm and a shear force VEd = 200 kN.

a) b)

List of contents

Simple joints

Examples

Hollow section


bases

Examples


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This lecture was prepared for the Edition 1 of SUSCOS

(2012/14) by RUI SIMES (UC) and FLOREA DINU (UPT).

Adaptations brought by J.P. Jaspart (Ulg)

for Edition 2 of SUSCOS

The SUSCOS powerpoints are covered by copyright and are for the exclusive use by theSUSCOS teachers in the framework of this Erasmus Mundus Master. They may be improved

by the various teachers throughout the different editions.


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Thank you

for your attention

http://steel.fsv.cvut.cz/suscos

module c design of steel members and joints

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