Specification for the Design of Steel Hollow Structural ...

1 CODE HSS 1997 6173 Specification for the Design of Steel Hollow Structural Sections April 15. 1997 ERJCAN INSTITUTE OF Steel CONSTR UCTION, INC. One East Wacker Drive, Suite 3100, C hi cago, IL60601 2001 " Specification FOR THE Design OF Steel Hollow Structural SECTIONS Copyright :I 1997 by American lnstitule of Sleel Construction, Inc. All righls resen'ed. This book or allY pari Ihereof must not be reproduced in any form without the written pennission of the p ublisher. The information presented in tbis publication bas been prepared in accordance with recognized engineering principles and is for general information only. While it is believed to be accurate, this information s hould not be used or relied upon for any specific application witbout competent professional examination and veri-fication of its accuracy, suitability, and applicability by a licensed professional engineer, designer, or architect.

2 The publication of the material contained 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 suitable for any general or particular use or offree-dom from infringement of any patent or patents. Any-one making use of this information assumes all liability arising from such usc. Caution must be exercised when relying upon other specifications and codes developed by other bodies and incorporated by reference herein s ince such material may be modified or amended from time to time sub-sequent to the printing of this edition. Tbe Institute bears no responsibility 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 AMEJUCAN 1'IS11Tt1TE Of STEELCONSTRL:C"nON \.

3 V1 0> SPECIFlCAnON FOR THE Design OF Steel Hollow Structural SECTIONS III Table of Contents Symbols Preface Specification for the Design of Steel Hollow Structura l Sections . v vii I. I. Scope .. I Malerial .. 1 I. Struclural Steel .. I 2. Design Wall Thickness 2 Loads and Load Combinalions 2 2 .1. Effective et Area for Tension Members. 2 2 .2. Local .. 4 I.. 4 2. Design by Plastic Analysis .. 4 3. Design in Seismic Applications 5 2 .3. Limiting Slenderness Ratios 5 Design for Tension .. 5 Effective Length and Slenderness Limitations 5 I. Effective Length .. 5 2. Design by PlastIc Analysis 6 Design for Compression 6 Design for Flexure 7 Design for Shear . 8 6. Design for Torsion 9 7. 1. Design for Combined Flexure and Axial Force 9 Design for Combined Tomon, Shear, Flexure, andlor Axial Force 10 8. Concentrated Forces on HSS.

4 II Concentrated Force DIstributed Transversely .. II Concentrated Force Distnbuted Longitudmally at the Center of the HSS Face .. 12 Concentrated Axial Force on Ihe End of a Rectangular HSS WIth a Cap Plate.. 12 General Provisions for Connections and Fasteners. 13 I. Through Bolts .. 13 2. Special Connectors . 13 3. TenSIOn Connectors. 13 IY Specification FOR THE Design OF Steel Structural SECTIONS Welds .. Other Connection Requirements I. Shear Rupture Strength .. 2. TenSIOn Rupture Strength 3. PunchJng Shear Rupture Strength 4. Eccentric Connections .. HSS-to-HSS Truss Connections I. DefinItions of Parameters 2. Criteria for Round HSS.. 2a . Limits of Applicability. 2b. Branches with Axial Loads 2c. Branches with Flexure .. 2d. Branches with Combined Axial Loads and Flexure . 3. Criteria for Rectangular HSS.

5 3a. Limits of Applicability .. 3b. Branches with Axial Loads in T-, Y-and Cross-connections 3c. Branches with Axial Loads in Gapped K-connections 3d. Branches with Bendmg .. 10. General Requirements for HSS Fabncauon Commentary Scope . Material Loads and Load Combinations 2 .1. Effective Net Area for Tension Members. Local Buckling .. Design for Tension Effecllve Length and Slenderness Limitations Design for Compression Design for Aexure Design for Shear . 6. Design for TorsIOn 13 14 14 15 15 15 15 16 16 17 17 18 18 18 19 19 20 21 22 23 25 27 29 29 30 30 31 35 36 37 Design for Combined Aexure and Axial Force 39 Design for Combined Torsion, Shear, Aexure, andlor Axial Force 40 8. Concentrated Forces on HSS .. General Provisions for Connections and Fasteners. Welds .. Other Connection Requirements.

6 HSS-to-HSS Truss Connections .. 10. General Requirements for HSS Fabrication References AMFJUCAN lNSlTTUTEOf STEELCONSTRUCTlON 41 43 43 44 45 48 50 <7> Specification FOR THE Design OF Steel Hollow STRUCfURAL SECTIONS v , ' V1 Symbols A area used to calculate A, A, gross area of cross-section A, effecllve net area for tension member All net area A. web area 8 overall width of rectangular HSS 8 . overall width of rectangular HSS branch member in a truss connection C HSS torsional constanl D outside diameter of round HSS D. outside diameter of round HSS branch member in a truss connection E modulus of elasticity F;r critical stress for column bu kling crilical stress for local buckhng en rica) stress for torsion F:t nominal SlfC~S for rectangular HSS shear resistance F. mintmum specified tensile mength of the HSS F'Kr critical !

7 Hear stress F. nummum specified yield stress of the HSS F',\ minimum specified yield strength of plate or connecting clement that is welded to an HSS nunimum specified yield strength of HSS branch member in a truss connections H overall height of rectangular HSS H. overall height of rectangular HSS branch member in a truss connection K compression member effective length factor L conneClion length length of weld 4 unbraced length 4 effeClive weld length L,.. maxmlUm unbraced length for plastic moment M, in plastiC analysis L, maximum unbraced length for yield moment M, M. nom mal /lexural strength M" pla~lic moment of sectlon M , yield mOment of section M, required /lexural strenglh M" resultant required /lex ural strength for round HSS M, smaller moment at end of an unbraced length in plastic analysis M , larger moment at end of an un braced length in plastic analysis N beanng length of concentrated load along length of HSS P.

8 Nominal axial strength Po reqUired aXial strength p. addillonal axial load for the moment in a rectangular HSS branch P, axial Yield load Q effecllve area factor Q, conneclton resistance reduction factor for compresSion in HSS (Section ). parameter u",d for tru" connections as defined 10 Secllon v, Specification FOR THE Design OF Steel Hollow Structural SECTIONS Q. parameler used for truss connecUons as defined in Section Qp parameler used for truss connecUons as defined in Secllon Rf reduclion faclor for wind forces on exposed HSS R, nominal strength of HSS and conneclions 10 HSS S elastic seclion modulus S<!! effecllve elaslic section modulus for thin-walled rectangular HSS nominal torsional strength reqUIred torsional strength U shear lag faclOr, parameter used for truss connections as defined in SectIOn V, nominal shear strength V.

9 Required shear strength Z plastic section modulus a length of essentially constant shear In a beam b nat WIdth of rectangular HSS nange or SIde, whICh is permitted to be taken as 8 -31 b, widlh of plate or connecting elemenl that IS welded to an HSS b,. parameter used for truss conneclions as defined in Secuon b,.. parameter used for truss conneCUons as defined in SectIon c constant for bending in rectangular HSS branches of tru~~ conneCllons d bolt dl3meter e eccentricity in K-connections f stress g gap between branch members In a gapped K-connecuon " nat WIdth of rectangular HSS web or SIde, which is penllltted to be taken as H -31 k distance from point of application of concentrated force 10 crilical section of HSS I member length r radIUS of gyrauon r, radIUS of gyralion aboul the y-axis Design HSS wall thickness as given in Section I, thickness of plate or connecling element thai is welded 10 an HSS I.

10 Thickness of branch member in an HSS truss connection !! plale thlckne;s (Secuon ) x eccentricity for shear lag a branch angle with respect to chord as illustrated in FIgure 1 a parameter used for truss connections as defined in Sectton ~ parameter used for truss connecUons as defined in Secllon ~". parameler used for truss connecUons as defined In Secllon ~ .. para meIer used for truss connectIOns as defined In SectIon ~ .. parameter used for truss connecllons", defined in Secllon y parameter used for truss conneClJons a~ defined in SeellO" cp rCMstance factor l] parameter used for truss connections as defined in Secllon A wall slenderness constant for type of load in round HSS truss connections A. column slenderness A, maXImum wall s lenderness for compact section A,. maximum wall slenderness for non-compact seclion a angle bel ween branch and chord ~ parameter used for truss conneCUons as defined III Secuon 9.