Jacobs 2010 Nascc

8/13/2019 Jacobs 2010 Nascc

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2010 NASCC / Structures Congress

Orlando, Florida

May 13, 2010


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Overview of Revisions to Chapter I in the 2010AISC Spec.

Section I6: Load Transfer

Outline


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Minimal Change?

2010 Chapter I


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Minimal Change?

2010 Chapter I

2005 Specification 2010 Specification


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5 Main Sections

Minimal Change?

2010 Chapter I



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5 Main Sections

12 Specification Pages

Minimal Change?

2010 Chapter I


9 Main Sections


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5 Main Sections


Minimal Change?

2010 Chapter I


9 Main Sections



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5 Main Sections


22 Commentary Pages

Minimal Change?

2010 Chapter I


9 Main Sections


h


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5 Main Sections


22 Commentary Pages

Minimal Change?

2010 Chapter I


9 Main Sections


41 Commentary Pages

2010 Ch I


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Concrete and Steel Reinforcement by Reference to ACI

Local Buckling Provisions for Axial and Flexural Members

Expanded and Clarified Load Transfer Provisions

Consolidated Shear Provisions

Added Diaphragm and Collector Beam Section

Added New Provisions for Shear Stud Strength

Major Revisions and Additions

2010 Chapter I

2010 Ch I


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2010 Chapter I

2010 Ch t I


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(Steel Anchors)


2010 Chapter I

2010 Ch t I


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(Steel Anchors) Did NOT Revise Standard Composite Beam Design and

Associated Anchor Strengths


2010 Chapter I

2010 Ch t I


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I1: General Provisions

I2: Axial Members I3: Flexural Members

I4: Combined Forces

I5: Special Cases

Outlines

2010 Chapter I


I1: General Provisions

I2: Axial Force I3: Flexure

I4: Shear

I5: Combined Forces

I6: Load Transfer

I7: Composite Diaphragms

I8: Steel Anchors

I9: Special Cases


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Overview of Revisions to Chapter I in the 2010AISC Spec.

Section I6: Load Transfer

Outline

I6 L d T f


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What Is Load Transfer?

I6: Load Transfer

I6 L d T f


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I6: Load Transfer

I6 Load T ansfe


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I6: Load Transfer

1. Force Introduction (I6.1)

I6: Load Transfer


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I6: Load Transfer


2. Force Allocation (I6.2)

I6: Load Transfer


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I6: Load Transfer



3. Force Transfer (I6.3)

I6: Load Transfer


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I6: Load Transfer




4. Detailing Provisions (I6.4)

I6 1: Force Introduction


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I6.1: Force Introduction


2. Force Allocation

3. Force Transfer

4. Detailing Provisions

I6 1: Force Introduction


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How is External Force Applied?

I6.1: Force Introduction


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I6 2: Force Allocation


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Force Allocation

I6.2: Force Allocation







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Force Allocation Requirement:


The applied external forces shall bedistributed within the composite sectionbased on the same ratio of steel section

strength to reinforced concrete sectionstrength as represented by the plasticcapacity model.



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Plastic Model


Encased Composite Columns

Pno = AsFy + AsrFysr+ 0.85Acfc (Eq. I2-4)



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Plastic Model






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Plastic Model






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Plastic Model




Filled Composite Columns

Pno = AsFy + C2fc (Ac+Asr x (Es/Ec))

(Eq. I2-9)



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Example


Pno = AsFy + AsrFysr+ 0.85Acfc

Say: AsFy = 67% of Total Pno


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Example






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Example






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Example






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Example




Vr = Pr (1-AsFy/Pno) Eq. I6-1

(For External Force Applied to Steel Only)

Vr = Pr (AsFy/Pno) Eq. I6-2

(For External Force Applied to Concrete Only)

I6 3: Force Transfer


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Force Transfer

I6.3: Force Transfer


2. Force Allocation (I6.2)3. Force Transfer (I6.3)

4. Detailing Provisions


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I6 3: Force Transfer


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Direct Bearing (I6.3a)

Shear Connection (I6.3b) Bond (I6.3c)

Mechanisms for Force Transfer


Filled Sections Encased Sections

Direct Bearing

Shear Connection

Rn Vr (LRFD)

Rn/ Vr (ASD)Rn = Mechanism Strength

Vr = Longitudinal Shear



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Rn=1.7fcA1

=0.65 (LRFD) =2.31 (ASD)


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Shear Connection (I8.3)


Table From Pallares and Hajjar, 2010


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Shear Connection Strength (I8.3)


hef/d > 4.0: 81% of Anchors Failed in Steel



2010 AISC Specification: Allows StrengthDetermination by Steel Strength Alone If

h/d>5.0

Rn = AscFu Eq. I8-3


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Shear Connection Strength (I8.3)

6 3 o ce a s e

Rn = AscFu Eq. I8-3

=0.65 (LRFD)

=2.31 (ASD)

Nanchors= Vr/ Rn

Nanchors= Vr/(Rn/)From Pallares and Hajjar, 2010



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Shear Connection (I8.3)

Steel Steel

Anchor Anchor

Diameter Area LRFD ASD

in (mm) in2 (mm

2) in (mm) in (mm) kips (kN) kips (kN)

3/4 0.44 3 3/4 5 1/4 18.7 12.4

(19) (284) (95) (133) (83) (55)

7/8 0.60 4 3/8 6 1/8 25.4 16.9

(22) (380) (110) (154) (113) (75)

1 0.79 5 7 33.2 22.1

(25) (491) (125) (175) (148) (98)

N1"h" refers to the installed height of the stud from the top of the stud head to the connected base.

N2Standard stock shear connectors as determined from Nelson Stud Welding S3L Type (Nelson, 2010) taking burnoff into account.

N3Available shear strength determined using Equation 2010 AISC I8-3 assuming Fu = 65 ksi (450 MPa).

3/4 x 4 3/16 3/4 x 5 7/8

7/8 x 5 3/16 7/8 x 7 3/16

1 x 6 1/4 N/A

Normal Weight Concrete Lightweight ConcreteAvailable Shear Strength

N3

Minimum Length

"h"N1

Minimum Length

"h"N1

Corresponding

Standard Stock

Shear ConnectorN2

Corresponding

Standard Stock

Shear ConnectorN2



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Bond (I6.3c)

Applicable to Filled Columns Only

60 psi Nominal Bond Strength (Fin)



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Bond (I6.3c)



For Rectangular Filled Columns:

Rn = B2CinFin =0.45 (LRFD)

=2.31 (ASD)

B = Width of Section at Loaded Face

Cin = 4 if connection away from ends of member, 2 if atend of member



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Bond (I6.3c)



For Circular Filled Columns:

Rn = 0.25D2CinFin =0.45 (LRFD)

=2.31 (ASD)

D = Outside Diameter of HSS

Cin = 4 if connection away from ends of member, 2 if atend of member

I6: Load Transfer


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Detailing Provisions




I6.4: Detailing


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Load Introduction Length

g

I6.4: Detailing


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Load Introduction Length

g

Steel Anchors required forencased columns along fulllength at 24 in. o.c. max

Filled Columns only require stud

anchors in load introductionzone (if used for sheartransfer).

Summary


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Summary

y





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Jacobs 2010 Nascc

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