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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, tion of bending strength, Structural, or Building 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
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