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Standar ec f icationsf or Str uctur Su ppor ts

or H g ay S ignsLu a r s , an

Tr a S gna s

Fifth Edition 2009

2010 Interim Revisions to

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2010 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.

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ISBN: 978-1-56051-492-3 Pub Code: LTS-5-I1

American Association of State Highway and Transportation Officials444 North Capitol Street, NW Suite 249Washington, DC 20001

202-624-5800 phone/202-624-5806 faxwww.transportation.org

2010 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication isa violation of applicable law.


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2010 INTERIM TO STANDARD SPECIFICATIONS

FOR STRUCTURAL SUPPORTS FOR HIGHWAYINSTRUCTIONS AND INFORMATION SIGNS, LUMINAIRES, AND TRAFFIC SIGNALS

iii

INSTRUCTIONS AND INFORMATION

GeneralAASHTO has issued proposed interim revisions to Standard Specifications for Structural Supports for Highway

Signs, Luminaires, and Traffic Signals , Fifth Edition (2009). This packet contains the revised pages. They are notdesigned to replace the corresponding pages in the book but rather to be kept with the book for fast reference.

Affected ArticlesUnderlined text indicates revisions that were approved in 2010 by the AASHTO Highways Subcommittee on Bridges

and Structures. Strikethrough text indicates any deletions that were likewise approved by the Subcommittee. A list ofaffected articles is included below.

All interim pages are printed on blue paper to make the changes stand out when inserted in the second edition binder.They also have a page header displaying the section number affected and the interim publication year. Please note thatthese pages may also contain nontechnical (e.g. editorial) changes made by AASHTO publications staff; any changes ofthis type will not be marked in any way so as not to distract the reader from the technical changes.

Please note that in response to user concerns, page breaks are now being added within sections betweennoncontiguous articles. This change makes it an option to insert the changes closer to the affected articles.

Table i2010 Changed Articles

SECTION 4: ANALYSIS AND DESIGNGENERAL CONSIDERATIONS

4.8.1

SECTION 6: ALUMINUM DESIGN

6.7.1 6.12


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2010 INTERIM TO STANDARD SPECIFICATIONSFOR STRUCTURAL SUPPORTS FOR HIGHWAY

SECTION 4 SIGNS, LUMINAIRES, AND TRAFFIC SIGNALS

1

SECTION 4: ANALYSIS AND DESIGNGENERALCONSIDERATIONS

4.8Second-Order Effects4.8.1Simplified MethodRevise the following paragraph as follows:

In the combined stress ratio equations, the bending stress for steel, f b , and aluminum (in Eq. 5-16 in(Article 5.12.1) and the bending stresses for aluminum, f b, f bx and f by, in and Eqs. 6-30 and 6-30a in (Article 6.7.1)),shall be divided by the coefficient of amplification, C A, to account for the secondary moment. The coefficient foramplification C A shall be taken as:


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All rights reserved. Duplication is a violation of applicable law.

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3

SECTION 6: ALUMINUM DESIGN

6.7Combined Stresses6.7.1Vertical Cantilever Pole-Type SupportsAdd the following before paragraph 2 of this Article:

In addition to Eq. 6-30, square extruded tubes used as vertical cantilever pole-type supports bent about a skewed(diagonal) axis shall satisfy the following requirement:

2

01.0bya bx s

sa A Abx by

f f f f F C F C F F

(6-30a)

f bx = bending stress about x axis

f by = bending stress about y axis

For tubes with all elements S S 1 (defined in Table 6-3):

= 1.60

cybx

y

F F

n (6-30b)

cyby

y

F F

n (6-30c)

For tubes with elements S 1 < S S 2 (defined in Table 6-3):

= 1.0

F bx = F b in Table 6-3

F by = F b in Table 6-3

C6.7.1Revise paragraph 2, sentence 4 as follows:

The term F a0 is used when the axial stress is small and the term f b /F b f a /F a0 is usually of negligible magnitude.

Add the following paragraph to the end of the Article:

Menzemer et al. (2009) compared theoretical diagonal bending to experimental tests. The interaction increase inallowable stress is justified for tubes bent about the diagonal for sections with limited width-thickness ratios. Althoughthe diagonal strength properties are significantly less than the primary axis properties, tests show additional strengthcompared with current strength predictions. For compact sections, the reserve strength is 33 percent higher for bendingabout a diagonal axis ( Z x / S x = 1.5) than about the principle axes ( Z x / S x = 1.13), where Z x and S x are plastic and elasticsection moduli, respectively.


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5

6.12REFERENCES

Add the following reference:

Menzemer, C., D. White, J. Bowman, and R. Minor. 2009. Bending of Hollow Aluminum Tubes about a DiagonalAxis, Light Metal Age . South San Francisco, CA. Vol. 67, No. 6, November/December 2009, pp. 2427.

2010 by the American Association of State Highway and Transportation Officials

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LTS-5-I1