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st ccodes & standards
Steel Design for the 21 Century o
By Christopher M. Hewitt d
The 1980s were pretty innovative years. They brought us performance of a steel beam is the same regardless of the design
wonderful technical advances, like cell phones, Microsoft method used by the structural engineer, only one set of curves is e
DOS, and AISC’s familiar ASD Manual. With time, each of required for structures designed by ASD or LRFD. The strength
these innovations has seen substantial improvement, embracing level corresponding to each point of the curve need only change s
the technical advances of the new century — none of us continue to refl ect whether the loads were calculated using ASD load
to carry around the combinations or LRFD
clunky car phones The Shape of Things load combinations. As &
of the 80s, but Shape information in the AISC Manual is based upon that which is published seen in Figure 1 on page
pocket sized phones in the ASTM A6 Standard. Many changes have occurred in the ASTM A6 29, this is accomplished
are now a way of standard since the printing of the last LRFD Manual, and even more have by providing an ASD
life. Bill Gates’ Mi- occurred since the printing of the last ASD Manual. The most signifi cant scale and an LRFD scale s
crosoft has evolved change is found in the W36 shapes series, in which an entire group of shapes for the vertical axis. All t
into an intricate and has been revised for current rolling practices. The k-distances for rolled shapes other tables similarly in- a
expanded Windows have also been updated to refl ect the variation in rolling practices of current tegrate ASD and LRFD
operating system for shape producers, values for convenient ©
with the presentation n
the business world. Copyright and consistent usage.
In that same time, the technology surround- of separate k-values
ing steel design has continued to advance. With applicable to the d
design and detailing Leading By Example
all of the research and innovation that has sur- of members. The AISC Committee on Manuals and Text-
faced in the last 16 years, it seems appropriate Pipe (ASTM A53) books began the effort of overhauling the Manual a
for steel design to evolve from a world defi ned and HSS (ASTM
by green computer screens, four-function cal- A500) members are three years ago. From the onset of the project, the r
culators, Beta recorders and Marty McFly. The treated similarly in the committee sought to return the text to its origins as
th 2005 Manual. The a true handbook for practicing structural engineers. d
13 Edition AISC Steel Construction Manual 7% reduction on the In line with this approach, users of the Manual will
gives ASD and LRFD designers alike a way to wall thickness that notice that there are no design examples included
realize the advances in steel design technology has historically been in the printed version. However, even more design s
st used in calculating
in the 21 century. the design properties examples than were available in the past are in-
One Manual to Rule Them All of HSS to account cluded on a CD companion titled AISC Design Ex-
for tolerances in the amples. The companion text was developed by the
The new AISC Steel Construction Manual, production process AISC Committee on Manuals and Textbooks with
th has now been applied
13 edition, brings ASD and LRFD together in the calculation of consultant Charles Page, P.E. of Page McNaghten
in a familiar context. The structure of the the design properties Associates in the Kansas City, Missouri area. AISC
book is largely the same as it has been for Design Examples provides hundreds of design ex-
STRUCTURE
many years — all of the classic design tables of Pipe cross-sections, amples on the application of the 2005 AISC Speci-
to account for a
for member and connection design have been common practice by fi cation for Structural Steel Buildings, and the de-
carried forward. Tabulated design values for HSS manufacturers sign aids of the AISC Steel Construction Manual,
ASD and LRFD are presented side-by-side. to downgrade their with an easy to follow, side-by-side presentation of
magazine
Much like the new AISC Specifi cation, the product and supply design equations.
Steel Construction Manual includes coverage it as meeting the
for all member requirements of More Design
ASTM A53
types, including without a pressure test. Power
hollow structural In addition to these broad updates, throughout the Manual, footnotes
sections and single have been added to point out shapes that require special design New design aids in
angles, in a single h this manual include
considerations. For example, the designation W40x593 indicates that tabulated values for
volume. the shape is a heavy section, with a fl ange thickness greater than 2 in., and
that special requirements may apply by Specifi cation Section A3.1. Or, the critical stress of
Defi ned By f compression mem-
the designation W14x99 highlights that when a W14x99 section is used in bers, design curves for
Color fl exure, it cannot be designed as a compact section. the available stress of
Color plays an plate girders, and sim-
important role in plifi ed design proce-
this edition of the Manual. Tabulated values applicable only dures for considering second-order effects on a structure.
to design by ASD are presented in green shading, and tabulated Many improvments realized in the development of the LRFD de-
values applicable only to design by LRFD are presented in sign manuals can now be used for design by ASD, such as improved
blue print. Values that are independent of design method are design methods for composite members, design aids for members
presented in black print. subjected to combined bending and axial forces, eccentric load
Perhaps the most elegant realization of this approach can be seen coeffi cients for loads applied at various angles, and tension
in the unbraced beam design charts of the Manual. Because the member design aids. But even these design aids have been im-
STRUCTURE magazine • December 2005 27
proved — tables for the
design of members sub-
jected to combined axial
load and bending now
can be applied to the
case of combined tensile
and bending forces, and
coeffi cients have been
provided for calculat-
ing the strength of weld
groups when they are
loaded concentrically. 0%
Some connection de-
sign procedures have
been modifi ed in this financing.
edition of the Manual.
Design procedures for
prying action now make 100% ©
use of the tensile strength Copyright
rather than the yield smart.
strength, to better align
the design provisions
with the tested perfor-
mance of bolted parts
subjected to prying ac-
tion. Procedures for the
F
design of connection el- If you use any qualifying or A
ements subject to bend- ® dv
Autodesk product, here’s er
ing have been modifi ed a deal that’s too good to tiser I
to use the plastic section pass up. Upgrade to one of nformation, visit
modulus in the calcula- our current Architectural,
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rather than the elastic
section modulus; the ex- Systems engineering solu- www
ception to this being the tions and you may be eli- .str
design of a coped beam Figure 1 gible for 0% financing for uctur
end for fl exure, which is 12 months. Certain product emag.org
STRUCTURE
still based upon the elastic section modulus. and credit restrictions apply,
Simple shear connections now include a revised design procedure for conventional and there’s a minimum
single-plate shear connections, a new design procedure for the design of extended single- purchase of $5,000. It’s a
plate shear connections, and the most current procedures for the design of end-plate great way to enjoy the latest
magazine
moment connections. Autodesk has to offer – at
But, perhaps the most signifi cant contribution of this Manual is that it recognizes that a cost that’s great for your
the strength of steel is constant, and eliminates the annoying differences between design bottom line.
methods, allowing the designer to scrutinize the merits of steel designs, rather than the merits
of design methods. By returning to a single design approach, a single Manual, and a single See how much
method for determining the strength of steel structures, structural engineers can better you can save at
pursue innovations and improvements in the art and practice of design.▪
autodesk.com/zeropercent
Christopher Hewitt is Staff Engineer in the AISC Engineering and
Research Department where he is directly responsible for the ongoing
development and maintenance of the AISC Steel Construction Manual.
Christopher serves as Secretary to the AISC Committee on Manuals and
Textbooks. He also serves on the NCSEA Advocacy Committee and the Lease applicants must meet credit quali-
ASCE Committee on Structural Connections. fications. Autodesk financing cannot be
combined with any other Autodesk promo-
tional or special price offer. USA and Canada
only. Federal government and student cus-
tomers are not eligible for this financing
offer. Autodesk is a registered trademark
of Autodesk, Inc., in the USA and/or other
countries. All other brand names, product
th names, or trademarks belong to their
The new 13 Edition AISC Steel Construction Manual will be respective holders. Autodesk reserves the
available beginning December, 2005 at www.aisc.org/bookstore. right to alter product offerings and speci-
fications at any time without notice, and
is not responsible for typographical or
graphical errors that may appear in this ad.
©2005 Autodesk, Inc. All rights reserved.
STRUCTURE magazine • December 2005 29
