# SAE J1093v001

SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243TO PLACE A DOCUMENT ORDER; (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS http://www.sae.orgCopyright 1994 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001INFORMATIONREPORTSubmitted for recognition as an American National StandardJ1093REV.MAR94Issued 1982-06Revised 1994-03Superseding J1093 JUN82(R) LATTICED CRANE BOOM SYSTEMS—ANALYTICAL PROCEDUREForeword—This Document has also changed to comply with the new SAE Technical Standards Board Format.Definitions has been changed to Section 3. All other section numbers have changed.1. Scope—This SAE Information Report applies to wire rope supported, latticed crane boom systems mountedon mobile construction type cranes for lift crane service.1.1 Purpose—The purpose of this document is to establish criteria for the analytical evaluation of the basicstructural competence of wire rope supported, latticed crane boom systems. The criteria and proceduresspecified include the evaluation of elastic stability for the overall boom system and individual members of thesystem.2. References2.1 Applicable Publications—The following publications form a part of the specification to the extent specifiedherein. Unless otherwise indicated the lastest revision of SAE publications shall apply.2.1.1 SAE PUBLICATIONS—Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.SAE J987—Crane Structures—Method of TestSAE 710697—Analysis of Pendant-Supported Latticed-Crane Booms, E. J. Vroonland, Sept. 19712.1.2 ANSI PUBLICATION—Available from ANSI, 11 West 42nd Street, New York, NY 10036-8002.ANSI A58.1-1982—Minimum Design Loads for Buildings and Other Structures2.1.3 OTHER PUBLICATIONS2.1.3.1 Timoshenko and Gere, “Theory of Elastic Stability,“ Second Ed., McGraw-Hill, New York, 1961.2.1.3.2 C. Lipson and N. J. Sheth, “Statistical Design and Analysis of Engineering Experiments,“ McGraw-Hill,Inc., 1973.SAE J1093 Revised MAR94-2-3. Definitions3.1 Boom—A member hinged to the front of the rotating upper structure with the outer end supported by ropesleading to a gantry, A-frame, or live mast. Its purpose is to support a lifted load.3.2 Boom Systems—A boom or boom and jib combination and the associated suspension system and supportingstructure.3.3 Buckling Ratio—Critical buckling is the loading condition where deflection becomes mathematicallyunbounded. Pcr/P is the ratio of the boom compression at buckling to the boom compression at rated load.Wcr/RL is the ratio of the lifted load at Pcr to rated load. In determining the buckling load of a boom, properconsideration must be given to the effects of any tapering sections of the boom or other variations in boomproperties which influence buckling. (See 2.1.1 and 2.1.3.)3.4 Chords—The main load-carrying members placed at the extreme corners of the boom or jib cross section.3.5 Gantry—A gantry (A-frame) is a structure mounted on the revolving upper structure of the machine to whichthe boom supporting ropes are attached.3.6 Jib—An extension mounted near the boom point to provide added length for lifting loads. The jib may be inline with the bottom or offset to various angles.3.7 Lacing Members—Structural truss members at angles to and supporting the chords in a lattice boom. Theyare open or closed members used to transmit shear loads and to maintain the geometry of the lattice boom.3.8 Lattice Boom (or Jib)—Constructed in the form of a truss with lacing members between the chords.3.9 Live Mast—Hinged structural member extending above the upper structure used for supporting a boom. Headof live mast is usually supported and raised or lowered by the boom hoist ropes.3.10 Mobile Construction Type Lifting Crane—Comprised of a boom system and hoisting mechanism attachedto an upper structure that is rotatably mounted to a mobile undercarriage. It is used for the purpose of liftingloads in the utilization and load spectrum of construction industry hook type lifting applications.3.11 Mathematical Symbols—Mathematical symbols not defined in this document are defined in SAE J987.Revised as suggested by Bonesteel.4. Applications—This calculation procedure references and is related to SAE J987 tests. Tests of selectedloading conditions from the ratings determined by this procedure or other limitations will verify calculated ClassIII and Class I (8.4.7 and SAE J987 - 9.1) stresses and overall deflections. The testing also evaluates Class IIareas not necessarily calculated by this procedure.Intended uses of this document include the following:4.1 A production boom system (serially produced) can be rated by this analytical procedure, but must be verified bytest procedures as specified in SAE J987.4.2 A production boom system that has been rated by 4.1 may be used on another machine provided that thissame analytical procedure shows that its stress levels will be less than in the original test application, andprovided that the supporting structure is as rigid as the structure used in 4.1. If these conditions are met, noadditional SAE J987 testing is required.SAE J1093 Revised MAR94-3-4.3 A specially designed boom system (not serially produced), similar to a known and tested design, may be ratedusing this analytical procedure. An overload test, as specified in SAE J987, should be applied.5. Rated Load Calculation for Boom5.1 Forces and Loadings—The forces considered to act on the boom structure for stress calculations shallinclude rated hook load, hoist, and boom suspension live loads including hoist line to drum offset, boomdeadweight loads, hoist rope, and boom suspension deadweight loads, a horizontal side load applied to theboom tip equal to 2% of the rated load, and the effects of boom foot inclination. Wind along with other in-service operating conditions combine to affect the crane operator s ability to control a load. The diversity ofload shapes, sizes, and lifting heights which occurs during crane operation makes the calculation of in-servicewind effect rather arbitrary for general crane rating considerations.5.1.1 The horizontal side load (2% of rated load) provides for the normal rating conditions associated with machineoperation, including wind effects, during lifting crane service with freely suspended loads.5.1.2 The dynamic effects of vertical acceleration or deceleration of the load are provided for by the requiredstrength margins.5.1.3 Consideration of factors beyond the manufacturer s normally specified rating conditions has not beenprovided for. While such factors may be appropriate for a specific operating condition, they are not applicableto ratings for general lift crane service. Such factors include traveling with a load, out-of-level operation, dutycycle operation, and unusual wind effects on the boom or lifted load.5.1.4 Boom foot inclination results from deformation of supporting structure. When the rated load on a leveledcrane is swung to some positions (i.e., corner), the boom foot support may become out of level due to thisdeformation (see also 4.2). This inclination can be determined by calculation or previous test experience ona similar supporting structure.5.1.5 The parts of hoist line used in this calculation should be the minimum required for the load being lifted. Theboom suspension shall be as specified by the manufacturer.5.2 Stress and Deflection Criteria—In this document, the calculated boom chord stress is the average stress at across section of the chord. This corresponds to the value Sra in the test standard SAE J987. It is intended thatthis calculation procedure be sufficiently accurate to determine the stress (Sra) and deflection (Zb), as definedin SAE J987. It is also intended that boom ratings determined by use of this calculation method shall becapable of passing SAE J987 test criteria. It is recognized that a test procedure measures all effects present atthe time of testing, some of which may not be practical or even possible to predict by calculation. To accountfor these effects, experience has shown that the following minimum recommended strength margins arerequired for calculated values of stress. The specified strength margins have been derived from the statisticalanalysis of hundreds of test results reflecting data on cranes from many manufacturers. For additionalbackground information concerning the determination of the specified strength margins refer to Appendix A.5.2.1 Tensile stresses in any boom chord or lacing member shall not exceed the member yield stress divided by1.69.5.2.2 Compression stress in any boom chord or lacing member shall not exceed the member critical stress (Scr)divided by 1.80. Scr shall be taken as defined in SAE J987, Appendix B.SAE J1093 Revised MAR94-4-5.2.3 The lateral deflection of the boom tip Zb, must be equal to or less than 2% of the boom length with the ratedload and sideload as defined per 5.1. (See Equation 1.)(Eq. 1)where:Zb = Boom point deflection from plane RLb = Length of boomNOTE—The sideload and boom foot inclination must be used in the calculation to determine Zb.5.3 Overall Boom Buckling—Buckling competence with the rated loads is determined by ratios Wcr/RL whereWcr is the hook load, which would produce critical buckling of the boom, and RL is the rated load and Pcr/Pwhere Pcr is the boom compression, which would cause critical buckling and P is the boom compression withrated load.5.3.1 The ratio Wcr/RL shall be greater than or equal to 1.50 in either plane.5.3.2 The ratio Pcr/P shall be greater than or equal to 1.30 in either plane.6. Erection Load Calculations for Boom6.1 Forces and Loadings—The forces considered to act on the boom structure during erection shall includeboom deadweight loads, hoist rope and boom suspension deadweight loads, and boom suspension forces.6.2 Stress Criteria6.2.1 Tensile stresses in any boom chord or lacing member shall not exceed the member yield stress divided by1.46.6.2.2 Compression stresses in any boom chord or lacing member shall not exceed the member critical stress (Scr)divided by 1.58. Scr shall be taken as defined in SAE J987.6.3 Overall Boom Buckling—Buckling competence with erection load is determined by the ratio Pcr/P.6.3.1 The ratio Pcr/P shall be greater than or equal to 1.30 in either plane.7. Out-of-Service Wind Calculation—The manufacturer shall specify the wind velocity at which the machineshould be considered to be out of service and the boom lowered to the ground or secured by some othermeans. The specified wind velocity shall be calculated based on boom strength and other considerations suchas stability. Analysis of the boom for out-of-service wind loadings may be performed using the methodsoutlined in this document (Section 8) in conjunction with wind forces developed by the methods shown inAppendix B.7.1 Out-of-Service Criteria for Boom Strength7.1.1 At the maximum rated boom angle, the boom shall have an adequate strength margin (8.3) when thespecified wind from the frontal direction forces the boom rearward into the boom stops. There is to be norated load or hoist-line weight considered to be acting at the boom tip. The weight of the hoist line running upthe boom and the load block or ball may be considered.Zb 0.02Lb≤SAE J1093 Revised MAR94-5-7.1.2 At any boom angle the specified wind forces acting on the boom, from any direction, shall not exceedadequate strength margins (7.3). There is to be no rated load acting at the boom tip. The weight of the hoistline running up the boom, the vertical parts of hoist line, and the load block or ball should be considered.7.2 Wind Loading Criteria7.2.1 The wind loadings considered to act on the boom shall be calculated as specified in Appendix B.7.2.2 In lieu of a specified exposure factor, “Exposure C“ from Table B1, Appendix B, should be used.7.3 Stress Criteria—The limiting stress criteria are to be the same as for rated loads per Section 5.8. Mathematical Methods—A classical mathematical method that can yield good comparison to test data ifproperly applied is presented as follows. Other acceptable methods, such as a nonlinear finite elementanalysis, can produce similar results if properly applied. In any case, the solution technique must accuratelyrepresent the physical system and include all the criteria and factors listed in 8.1 to 8.4.The equations presented in this document are based on a beam-column analytical model of the boom in whichthe main chords act together to resist axial compressive loads and bending as extreme fibers in a built-up crosssection. The lacing members serve to transmit shear, brace the main chords, and provide cross-sectionalstability. The flexural properties (EI) of the boom cross section are based on the moment of inertia (I) of thechord areas with respect to the centroid of the boom, and the material modulus of elasticity (E).The solutions of the differential equations in 8.1 have proven to yield good correlation to test data. For typicalequation solutions, see 3.1.1.2 and 3.1.3.1 which only define a simplified model of a boom and do not containall the factors listed in 8.1.The mathematical analysis of the beam column shall consider both the in-plane and out-of-plane cases.8.1 In-Plane Analysis—The in-plane case refers to the calculation of deflections (y) in the vertical plane throughthe centerline of the boom as a function of the distance from the boom foot (x). The general in-plane equationis shown in Equation 2:(Eq. 2)where:P = Boom compression due to boom point forcesQ = Boom compression due to the intermediate suspensionY(x) = Moment function of x which should include the effects of:a. force due to lifted loadb. suspension line forcec. boom weight distributiond. boom point offset from the nominal boom centerlinee. forces due to load hoist linef. vertical eccentricityg. forces due to intermediate suspensionh. wind fore or aft force (out-of-service condition only)Eld2ydx2-------- Yx()PyQy++=–SAE J1093 Revised MAR94-6-8.2 Out-of-Plane Analysis—The out-of-plane case refers to the calculation of deflections (z) in the transverseplane through the centerline of the boom as a function of the distance from the boom foot (x). The general out-of-plane equation is shown in Equation 3:(Eq. 3)where:Z(x) = Moment function of x which should include effects of:a. 2% side loadb. boom foot inclinationc. horizontal force f