7 Steel Design Guide Industrial Buildings Roofs to Anchor Rods Second Edition 7 Steel Design Guide Industrial Buildings Roofs to Anchor Rods Second Edition James M. Fisher Computerized Structural Design, Inc. Milwaukee, WI AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC. Copyright © 2004 by American Institute of Steel Construction, Inc. All rights reserved. This book or any part thereof must not be reproduced in any form without the written permission of the publisher. The information presented in this publication has been prepared in accordance with recognized engineering principles and is for general information only. While it is believed to be accurate, this information should not be used or relied upon for any specific application without com- petent professional examination and verification of its accuracy, suitability, and applicability by a licensed professional engineer, designer, or architect. The publication of the material con- tained herein is not intended as a representation or warranty on the part of the American Institute of Steel Construction or of any other person named herein, that this information is suit- able for any general or particular use or of freedom from infringement of any patent or patents. Anyone making use of this information assumes all liability arising from such use. Caution must be exercised when relying upon other specifications and codes developed by other bodies and incorporated by reference herein since such material may be modified or amended from time to time subsequent to the printing of this edition. The Institute bears no responsi- bility for such material other than to refer to it and incorporate it by reference at the time of the initial publication of this edition. Printed in the United States of America First Printing: March 2005 Acknowledgements The author would like to thank Richard C. Kaehler, L.A. The author also thanks the American Iron and Steel Insti- Lutz, John A. Rolfes, Michael A. West, and Todd Alwood tute for their funding of the first edition of this guide. for their contributions to this guide. Special appreciation is also given to Carol T. Williams for typing the manuscript. v Table of Contents PART1 1. INDUSTRIALBUILDINGS—GENERAL....................................................................................................................1 2. LOADINGCONDITIONS AND LOADINGCOMBINATIONS................................................................................1 3. OWNER-ESTABLISHED CRITERIA ..........................................................................................................................2 3.1 Slab-on-Grade Design............................................................................................................................................2 3.2 Gib Cranes..............................................................................................................................................................2 3.3 Interior Vehicular Traffic........................................................................................................................................3 3.4 Future Expansion....................................................................................................................................................3 3.5 Dust Control/Ease of Maintenance ........................................................................................................................3 4. ROOFSYSTEMS..............................................................................................................................................................3 4.1 Steel Deck for Built-up or Membrane Roofs ........................................................................................................4 4.2 Metal Roofs............................................................................................................................................................5 4.3 Insulation and Roofing............................................................................................................................................5 4.4 Expansion Joints ....................................................................................................................................................6 4.5 Roof Pitch, Drainage, and Ponding........................................................................................................................7 4.6 Joists and Purlins....................................................................................................................................................9 5. ROOFTRUSSES..............................................................................................................................................................9 5.1 General Design and Economic Considerations....................................................................................................10 5.2 Connection Considerations ..................................................................................................................................11 5.3 Truss Bracing........................................................................................................................................................11 5.4 Erection Bracing ..................................................................................................................................................13 5.5 Other Considerations............................................................................................................................................14 6. WALLSYSTEMS............................................................................................................................................................15 6.1 Field-Assembled Panels........................................................................................................................................15 6.2 Factory-Assembled Panels....................................................................................................................................16 6.3 Precast Wall Panels ..............................................................................................................................................16 6.4 Mansory Walls......................................................................................................................................................17 6.5 Girts......................................................................................................................................................................17 6.6 Wind Columns......................................................................................................................................................19 7. FRAMINGSCHEMES ..................................................................................................................................................19 7.1 Braced Frames vs. Rigid Frames..........................................................................................................................19 7.2 HSS Columns vs. WShapes ................................................................................................................................20 7.3 Mezzanine and Platform Framing........................................................................................................................20 7.4 Economic Considerations ....................................................................................................................................20 8. BRACINGSYSTEMS....................................................................................................................................................21 8.1 Rigid Frame Systems............................................................................................................................................21 8.2 Braced Systems ....................................................................................................................................................22 8.3 Temporary Bracing ..............................................................................................................................................24 9. COLUMN ANCHORAGE ............................................................................................................................................26 9.1 Resisting Tension Forces with Anchore Rods......................................................................................................26 9.2 Resisting Shear Forces Using Anchore Rods ......................................................................................................31 9.3 Resisting Shear Forces Through Bearing and with Reinforcing Bards ..............................................................32 9.4 Column Anchorage Examples (Pinned Base)......................................................................................................34 9.5 Partial Base Fixity................................................................................................................................................39 vii 10. SERVICEABILITYCRITERIA ..................................................................................................................................39 10.1 Serviceability Criteria for Roof Design................................................................................................................40 10.2 Metal Wall Panels ................................................................................................................................................40 10.3 Precast Wall Panels ..............................................................................................................................................40 10.4 Masonry Walls......................................................................................................................................................41 PART2 11. INTRODUCTION ..........................................................................................................................................................43 11.1 AISE Technical Report 13 Building Classifications............................................................................................43 11.2 CMAA70 Crane Classifications..........................................................................................................................43 12. FATIGUE ........................................................................................................................................................................45 12.1 Fatigue Damage....................................................................................................................................................45 12.2 Crane Runway Fatigue Considerations................................................................................................................47 13. CRANE INDUCED LOADS AND LOAD COMBINATIONS ..................................................................................48 13.1 Vertical Impact......................................................................................................................................................49 13.2 Side Thrust............................................................................................................................................................49 13.3 Longitudinal or Tractive Force ............................................................................................................................50 13.4 Crane Stop Forces ................................................................................................................................................50 13.5 Eccentricities ........................................................................................................................................................50 13.6 Seismic Loads ......................................................................................................................................................50 13.7 Load Combinations ..............................................................................................................................................51 14. ROOFSYSTEMS............................................................................................................................................................52 15. WALLSYSTEMS............................................................................................................................................................52 16. FRAMINGSYSTEMS....................................................................................................................................................53 17. BRACINGSYSTEMS....................................................................................................................................................53 17.1 Roof Bracing ........................................................................................................................................................53 17.2 Wall Bracing ........................................................................................................................................................54 18. CRANE RUNWAYDESIGN..........................................................................................................................................55 18.1 Crane Runway Beam Design Procedure (ASD)..................................................................................................56 18.2 Plate Girders..........................................................................................................................................................61 18.3 Simple Span vs. Continuous Runways ................................................................................................................62 18.4 Channel Caps........................................................................................................................................................64 18.5 Runway Bracing Concepts....................................................................................................................................64 18.6 Crane Stops ..........................................................................................................................................................65 18.7 Crane Rail Attachments........................................................................................................................................65 18.7.1 Hook Bolts ............................................................................................................................................65 18.7.2 Rail Clips ..............................................................................................................................................65 18.7.3 Rail Clamps ..........................................................................................................................................66 18.7.4 Patented Rail Clips................................................................................................................................66 18.7.5 Design of Rail Attachments..................................................................................................................66 18.8 Crane Rails and Crane Rail Joints........................................................................................................................67 19. CRANE RUNWAYFABRICATION AND ERECTION TOLERANCES................................................................67 20. COLUMN DESIGN........................................................................................................................................................69 20.1 Base Fixity and Load Sharing..............................................................................................................................69 20.2 Preliminary Design Methods................................................................................................................................72 20.2.1 Obtaining Trial Moments of Inertia for Stepped Columns ..................................................................74 20.2.2 Obtaining Trial Moments of Inertia for Double Columns....................................................................74 20.3 Final Design Procedures (Using ASD) ................................................................................................................74 20.4 Economic Considerations ....................................................................................................................................80 viii 21. OUTSIDE CRANES ......................................................................................................................................................81 22. UNDERHUNGCRANES ..............................................................................................................................................82 23. MAINTENANCE AND REPAIR..................................................................................................................................83 24. SUMMARYAND DESIGN PROCEDURES ..............................................................................................................83 REFERENCES ..........................................................................................................................................................................83 APPENDIX A ............................................................................................................................................................................87 APPENDIX B ............................................................................................................................................................................89 ix Part 1 INDUSTRIAL BUILDINGS—GENERAL 1. INTRODUCTION 2. Live load: This load represents the force imposed on the structure by the occupancy and use of the building. Although the basic structural and architectural components Building codes give minimum design live loads in of industrial buildings are relatively simple, combining all pounds per square foot, which vary with the classifi- of the elements into a functional economical building can cation of occupancy and use. While live loads are be a complex task. General guidelines and criteria to expressed as uniform, as a practical matter any occu- accomplish this task can be stated. The purpose of this pancy loading is inevitably nonuniform. The degree guide is to provide the industrial building designer with of nonuniformity that is acceptable is a matter of engi- guidelines and design criteria for the design of buildings neering judgment. Some building codes deal with without cranes, or for buildings with light-to-medium duty nonuniformity of loading by specifying concentrated cycle cranes. Part 1 deals with general topics on industrial loads in addition to uniform loading for some occu- buildings. Part 2 deals with structures containing cranes. pancies. In an industrial building, often the use of the Requirements for seismic detailing for industrial buildings building may require a live load in excess of the code have not been addressed in this guide. The designer must stated minimum. Often this value is specified by the address any special detailing for seismic conditions. owner or calculated by the engineer. Also, the loading Most industrial buildings primarily serve as an enclosure may be in the form of significant concentrated loads as for production and/or storage. The design of industrial in the case of storage racks or machinery. buildings may seem logically the province of the structural engineer. It is essential to realize that most industrial build- 3. Snow loads: Most codes differentiate between roof ings involve much more than structural design. The live and snow loads. Snow loads are a function of designer may assume an expanded role and may be respon- local climate, roof slope, roof type, terrain, building sible for site planning, establishing grades, handling surface internal temperature, and building geometry. These drainage, parking, on-site traffic, building aesthetics, and, factors may be treated differently by various codes. perhaps, landscaping. Access to rail and the establishment of proper floor elevations (depending on whether direct 4. Rain loads: These loads are now recognized as a sep- fork truck entry to rail cars is required) are important con- arate loading condition. In the past, rain was siderations. Proper clearances to sidings and special atten- accounted for in live load. However, some codes have tion to curved siding and truck grade limitations are also a more refined standard. Rain loading can be a func- essential. tion of storm intensity, roof slope, and roof drainage. There is also the potential for rain on snow in certain 2. LOADING CONDITIONS AND LOADING regions. COMBINATIONS 5. Wind loads: These are well codified, and are a func- Loading conditions and load combinations for industrial tion of local climate conditions, building height, build- buildings without cranes are well established by building ing geometry and exposure as determined by the codes. surrounding environment and terrain. Typically, Loading conditions are categorized as follows: they’re based on a 50-year recurrence interval—max- 1. Dead load: This load represents the weight of the imum three-second gust. Building codes account for structure and its components, and is usually expressed increases in local pressure at edges and corners, and in pounds per square foot. In an industrial building, often have stricter standards for individual compo- the building use and industrial process usually involve nents than for the gross building. Wind can apply both permanent equipment that is supported by the struc- inward and outward forces to various surfaces on the ture. This equipment can sometimes be represented building exterior and can be affected by size of wall by a uniform load (known as a collateral load), but the openings. Where wind forces produce overturning or points of attachment are usually subjected to concen- net upward forces, there must be an adequate counter- trated loads that require a separate analysis to account balancing structural dead weight or the structure must for the localized effects. be anchored to an adequate foundation. DESIGN GUIDE 7 / INDUSTRIAL BUILDINGS—ROOFS TO ANCHOR RODS,2ND EDITION/1 6. Earthquake loads: Seismic loads are established by There are instances where loads in excess of code mini- building codes and are based on: mums are required. Such cases call for owner involvement. The establishment of loading conditions provides for a a. The degree of seismic risk structure of adequate strength. Arelated set of criteria are b. The degree of potential damage needed to establish the serviceability behavior of the struc- c. The possibility of total collapse ture. Serviceability design considers such topics as deflec- d. The feasibility of meeting a given level of protec- tion, drift, vibration and the relation of the primary and tion secondary structural systems and elements to the perform- Earthquake loads in building codes are usually equiva- ance of nonstructural components such as roofing, lent static loads. Seismic loads are generally a function of: cladding, equipment, etc. Serviceability issues are not strength issues but maintenance and human response con- a. The geographical and geological location of the siderations. Serviceability criteria are discussed in detail in building Serviceability Design Considerations for Steel Buildings b. The use of the building that is part of the AISC Steel Design Guide Series (Fisher, c. The nature of the building structural system 2003). Criteria taken from the Design Guide are presented d. The dynamic properties of the building in this text as appropriate. e. The dynamic properties of the site As can be seen from this discussion, the design of an f. The weight of the building and the distribution of industrial building requires active owner involvement. This the weight is also illustrated by the following topics: slab-on-grade Load combinations are formed by adding the effects of design, jib cranes, interior vehicular traffic, and future loads from each of the load sources cited above. Codes or expansion. industry standards often give specific load combinations that must be satisfied. It is not always necessary to consider 3.1 Slab-on-Grade Design all loads at full intensity. Also, certain loads are not required One important aspect to be determined is the specific load- to be combined at all. For example, wind need not be com- ing to which the floor slab will be subjected. Forklift bined with seismic. In some cases only a portion of a load trucks, rack storage systems, or wood dunnage supporting must be combined with other loads. When a combination heavy manufactured items cause concentrated loads in does not include loads at full intensity it represents a judg- industrial structures. The important point here is that these ment as to the probability of simultaneous occurrence with loadings are nonuniform. The slab-on-grade is thus often regard to time and intensity. designed as a plate on an elastic foundation subject to con- centrated loads. 3. OWNER-ESTABLISHED CRITERIA It is common for owners to specify that slabs-on-grade be Every industrial building is unique. Each is planned and designed for a specific uniform loading (for example, 500 constructed to requirements relating to building usage, the psf). If a slab-on-grade is subjected to a uniform load, it process involved, specific owner requirements and prefer- will develop no bending moments. Minimum thickness and ences, site constraints, cost, and building regulations. The no reinforcement would be required. The frequency with process of design must balance all of these factors. The which the author has encountered the requirement of design owner must play an active role in passing on to the designer for a uniform load and the general lack of appreciation of all requirements specific to the building such as: the inadequacy of such criteria by many owners and plant engineers has prompted the inclusion of this topic in this 1. Area, bay size, plan layout, aisle location, future guide. Real loads are not uniform, and an analysis using an expansion provisions. assumed nonuniform load or the specific concentrated load- 2. Clear heights. ing for the slab is required. An excellent reference for the design of slabs-on-grade is Designing Floor Slabs on 3. Relations between functional areas, production flow, Grade by Ringo and Anderson (Ringo, 1996). In addition, acoustical considerations. the designer of slabs-on-grade should be familiar with the ACI Guide for Concrete Floor and Slab Construction(ACI, 4. Exterior appearance. 1997), the ACI Design of Slabs on Grade(ACI, 1992). 5. Materials and finishes, etc. 3.2 Jib Cranes 6. Machinery, equipment and storage method. Another loading condition that should be considered is the installation of jib cranes. Often the owner has plans to 7. Loads. 2/ DESIGN GUIDE 7 / INDUSTRIAL BUILDINGS—ROOFS TO ANCHOR RODS,2ND EDITION install such cranes at some future date. But since they are a 1. The directions of principal and secondary framing purchased item—often installed by plant engineering per- members require study. In some cases it may prove sonnel or the crane manufacturer—the owner may inadver- economical to have a principal frame line along a tently neglect them during the design phase. building edge where expansion is anticipated and to Jib cranes, which are simply added to a structure, can cre- design edge beams, columns and foundations for the ate a myriad of problems, including column distortion and future loads. If the structure is large and any future misalignment, column bending failures, crane runway and expansion would require creation of an expansion crane rail misalignment, and excessive column base shear. joint at a juncture of existing and future construction, It is essential to know the location and size of jib cranes in it may be prudent to have that edge of the building advance, so that columns can be properly designed and consist of nonload-bearing elements. Obviously, proper bracing can be installed if needed. Columns sup- foundation design must also include provision for porting jib cranes should be designed to limit the deflection expansion. at the end of the jib boom to boom length divided by 225. 2. Roof Drainage: An addition which is constructed with 3.3 InteriorVehicularTraffic low points at the junction of the roofs can present seri- ous problems in terms of water, ice and snow piling The designer must establish the exact usage to which the effects. structure will be subjected. Interior vehicular traffic is a major source of problems in structures. Forklift trucks can 3. Lateral stability to resist wind and seismic loadings is accidentally buckle the flanges of a column, shear off often provided by X-bracing in walls or by shear anchor rods in column bases, and damage walls. walls. Future expansion may require removal of such Proper consideration and handling of the forklift truck bracing. The structural drawings should indicate the problem may include some or all of the following: critical nature of wall bracing, and its location, to pre- 1. Use of masonry or concrete exterior walls in lieu of vent accidental removal. In this context, bracing can metal panels. (Often the lowest section of walls is interfere with many plant production activities and the made of masonry or concrete with metal panels used importance of such bracing cannot be overemphasized for the higher section.) to the owner and plant engineering personnel. Obvi- ously, the location of bracing to provide the capability 2. Installation of fender posts (bollards) for columns and for future expansion without its removal should be the walls may be required where speed and size of fork goal of the designer. trucks are such that a column or load-bearing wall could be severely damaged or collapsed upon impact. 3.5 Dust Control/Ease of Maintenance 3. Use of metal guardrails or steel plate adjacent to wall In certain buildings (for example, food processing plants) elements may be in order. dust control is essential. Ideally there should be no horizon- tal surfaces on which dust can accumulate. HSS as purlins 4. Curbs. reduce the number of horizontal surfaces as compared to Lines defining traffic lanes painted on factory floors have C’s, Z’s, or joists. If horizontal surfaces can be tolerated in never been successful in preventing structural damage from conjunction with a regular cleaning program, C’s or Z’s interior vehicular operations. The only realistic approach may be preferable to joists. The same thinking should be for solving this problem is to anticipate potential impact and applied to the selection of main framing members (in other damage and to install barriers and/or materials that can words, HSS or box sections may be preferable to wide- withstand such abuse. flange sections or trusses). 3.4 Future Expansion 4. ROOFSYSTEMS Except where no additional land is available, every indus- The roof system is often the most expensive part of an trial structure is a candidate for future expansion. Lack of industrial building (even though walls are more costly per planning for such expansion can result in considerable square foot). Designing for a 20-psf mechanical surcharge expense. load when only 10 psf is required adds cost over a large When consideration is given to future expansion, there area. are a number of practical considerations that require evalu- Often the premise guiding the design is that the owner ation. will always be hanging new piping or installing additional equipment, and a prudent designer will allow for this in the DESIGN GUIDE 7 / INDUSTRIAL BUILDINGS—ROOFS TO ANCHOR RODS,2ND EDITION/3