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AISC Steel Design Philosophies

The document discusses two philosophies of structural steel design: Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD). It provides details on the key differences between the two approaches, including how loads and resistances are factored. It also lists the standard load combinations specified in LRFD and provides an overview of the chapter organization of the 13th and 14th editions of the AISC Steel Construction Manual.

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Dan Roberts
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92 views8 pages

AISC Steel Design Philosophies

The document discusses two philosophies of structural steel design: Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD). It provides details on the key differences between the two approaches, including how loads and resistances are factored. It also lists the standard load combinations specified in LRFD and provides an overview of the chapter organization of the 13th and 14th editions of the AISC Steel Construction Manual.

Uploaded by

Dan Roberts
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Elie G. Hantouche, Ph.D.

•AISC 360-05 Specification for Structural Steel Buildings


1
Philosophies of Design

• ASD - Allowable
All bl Stress
St Design
D i

•LRFD - Load and Resistance Factor Design

2
Philosophies of Design

ASD: Allowable Stress Design (1924)

For Safety :

• f - Computed Stress (service)


• FA - Allowable Stress (service)

Everything is service and not factored……

ASD does not recognize different variabilities of different load types.


3
Philosophies of Design

LRFD: Load & Resistance Factor Design (1986)

F Safety:
For S f t

¾ Q - Load Effect
¾ Rn - Component Resistance
¾ γ - Load Factor
¾ φ - Resistance Factor

The LRFD philosophy provides a more uniform,


systematic, and rational approach to the selection
of load factors and resistance factors than ASD.

4
Load Combinations

LRFD
(1) 1.4D
(2) 1.2D + 1.6L + 0.5(Lr or S or R)
(3) 1
1.2D
2D + 1
1.6(Lr
6(Lr or S or R) + (0
(0.5L
5L or 0
0.8W)
8W)
(4) 1.2D + 1.6W + 0.5L + 0.5(Lr or S or R)
(5) 1.2D ± 1.0E + 0.5L + 0.2S
(6) 0.9D ± (1.6W or 1.0E)

Consistent with ASCE 7, Based on 50 yr Recurrence Interval.

5
AISC Steel Construction Manual, 13th and 14th Edition

6
AISC Steel Construction Manual, 13th Edition

1. Dimensions and Properties


2 General Design Considerations
2.
3. Design of Flexural Members
4. Design of Compression Members
5. Design of Tension Members
6. Design of Members Subject to Combined Loading
7 Design
7. D i C Consideration
id ti ffor B
Bolts
lt
8. Design Considerations for Welds
9. Design
g of Connecting
g Elements

7
AISC Steel Construction Manual, 13th Edition

10. Design of Simple Shear Connections


11. Design of Flexible Moment Connections
12. Design of Fully Restrained Moment Connections
13 Design of Bracing Connections and Truss Connections
13.
14. Design of Bearing Plates, Base Plates, and Column Splices
15. Design of Hanger Connections, Brackets Plates, etc.
16. Specifications and Codes
17. Miscellaneous Data and Mathematical Information
Index

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