POST-FRAME BUILDING DESIGN MANUAL Second Edition Copyright © 2015, 2016. All rights reserved. This book may not be reproduced in whole or in part by any means (with the exception of short quotations for the purpose of review) without the permission of the publisher. For information, contact the National Frame Building Association (NFBA). NFBA, its members, and its agents make no warranty, either expressed or implied, including but not limited to any implied warranties of fitness for a particular purpose regarding these design practices. NFBA shall assume no responsibility for the sufficiency or completeness of the information contained herein. Any practice de- scribed in the manual should be applied by the building professional in accordance with the most current profes- sional standards applicable in the specific situation. In no event shall NFBA be liable to anyone for special, collateral, incidental, or consequential damages in connec- tion with or arising out of the purchase or use of the materials in this manual, and the sole and exclusive liability to NFBA, regardless of the form of action, shall not exceed the purchase price of the manual. Moreover, NFBA shall not be liable for any claim of any kind whatsoever against the user of these materials by any other party. NFBA is not responsible for statements and opinions advanced in its meetings or printed in its publications. Such statements and opinions represent the view of the individual to whom they are credited and are not binding on the association as a whole. National Frame Building Association 8735 W. Higgins Road, Suite 300 Chicago, IL 60631-2738 Phone: 800.557.6957 www.nfba.org Contents Acknowledgements . vi 1 Introduction to Post-Frame Buildings 1.1 General . 1-1 1.2 ANSI/ASABE S618 Definitions . 1-1 1.3 General Building Terminology . 1-13 1.4 History . 1-16 1.5 Advantages . 1-21 1.6 Ideal Structural Applications . 1-23 1.7 References . 1-34 1.8 Acknowledgements . 1-35 2 Building Regulations 2.1 Introduction . 2-1 2.2 Standards . 2-1 2.3 Building Codes . 2-2 2.4 International Building Code . 2-4 2.5 Federal Codes . 2-12 2.6 NFBA Sponsored Fire Tests . 2-12 2.7 Zoning Regulations . 2-15 2.8 Codes and Farm Buildings . 2-15 2.9 Significant Design Documents . 2-16 2.10 References . 2-26 3 Structural Load and Deflection Criteria 3.1 Introduction . 3-1 3.2 Load Standards . 3-1 3.3 Building Risk Categories . 3-2 3.4 Load Types . 3-2 3.5 Load Combinations . 3-4 3.6 Tributary Area . 3-5 3.7 Load Representations . 3-6 3.8 Dead Loads . 3-8 3.9 Live Loads . 3-9 3.10 Snow Loads . 3-10 3.11 Wind Loads . 3-11 3.12 Seismic Loads . 3-13 3.13 Deflection . 3-13 3.14 References . 3-14 4 Structural Design Overview 4.1 Introduction . 4-1 4.2 Broad Overview . 4-1 4.3 Posts . 4-2 4.4 Trusses . 4-3 4.5 Girders . 4-5 4.6 Knee Braces . 4-5 4.7 Roof Purlins . 4-5 4.8 Wall Girts . 4-6 4.9 Large Doors . 4-7 4.10 Roof and Ceiling Diaphragms . 4-7 4.11 Shearwalls . 4-7 4.12 Decay Resistance of Wood . 4-7 4.13 Electrochemical Corrosion Resistance of Metals . 4-8 4.14 References . 4-11 5 Post and Pier Foundation Design 5.1 Introduction . 5-1 5.2 Definitions . 5-2 5.3 Soil Characteristics, Classification and Use . 5-4 5.4 Engineering Properties of Soil . 5-8 5.5 Foundation Material Properties . 5-11 5.6 Structural Analysis . 5-12 5.7 Governing Strength Equations . 5-19 5.8 Bearing Strength Assessment . 5-22 5.9 Lateral Strength Assessment . 5-25 5.10 Uplift Strength Assessment . 5-37 5.11 Frost Heave Considerations . 5-40 5.12 Installation Requirements . 5-40 5.13 References . 5-41 6 Diaphragm Design 6.1 Introduction . 6-1 6.2 Structural Model . 6-2 6.3 Frame Stiffness, k . 6-3 6.4 Diaphragm Stiffness, Ch . 6-10 6.5 Eave Load, R . 6-10 6.6 Load Distribution . 6-14 6.7 Component Design . 6-25 6.8 Rigid Roof Design . 6-29 6.9 References . 6-30 7 Metal-Clad Wood-Frame Diaphragm Properties 7.1 Introduction . 7-1 7.2 Design Variables . 7-2 7.3 Diaphragm Test Assemblies . 7-2 7.4 Building Diaphragm Properties . 7-5 7.5 Building Shearwall Properties . 7-5 7.6 Tabulated Data . 7-5 7.7 Example Calculations . 7-12 7.8 References . 7-12 8 Post Design 8.1 Introduction . 8-1 8.2 Post Definitions . 8-1 8.3 Relative Cost . 8-2 8.4 Preservative Treatment . 8-3 8.5 Corrosion Potential . 8-4 8.6 Bending Characteristics . ..