ANSI EP484.2-1998 Diaphragm Design of Metal-Clad Wood-Frame Rectangular Buildings.pdf

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1、 ANSI/ASAE EP484.2 JUN1998 (R2012) Diaphragm Design of Metal-Clad, Wood-Frame Rectangular Buildings American Society of Agricultural and Biological Engineers ASABE is a professional and technical organization, of members worldwide, who are dedicated to advancement of engineering applicable to agricu

2、ltural, food, and biological systems. ASABE Standards are consensus documents developed and adopted by the American Society of Agricultural and Biological Engineers to meet standardization needs within the scope of the Society; principally agricultural field equipment, farmstead equipment, structure

3、s, soil and water resource management, turf and landscape equipment, forest engineering, food and process engineering, electric power applications, plant and animal environment, and waste management. NOTE: ASABE Standards, Engineering Practices, and Data are informational and advisory only. Their us

4、e by anyone engaged in industry or trade is entirely voluntary. The ASABE assumes no responsibility for results attributable to the application of ASABE Standards, Engineering Practices, and Data. Conformity does not ensure compliance with applicable ordinances, laws and regulations. Prospective use

5、rs are responsible for protecting themselves against liability for infringement of patents. ASABE Standards, Engineering Practices, and Data initially approved prior to the society name change in July of 2005 are designated as “ASAE“, regardless of the revision approval date. Newly developed Standar

6、ds, Engineering Practices and Data approved after July of 2005 are designated as “ASABE“. Standards designated as “ANSI“ are American National Standards as are all ISO adoptions published by ASABE. Adoption as an American National Standard requires verification by ANSI that the requirements for due

7、process, consensus, and other criteria for approval have been met by ASABE. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple

8、majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. CAUTION NOTICE: ASABE and ANSI standards may be revised or withdrawn at any time. Additionally, procedures of ASABE require that actio

9、n be taken periodically to reaffirm, revise, or withdraw each standard. Copyright American Society of Agricultural and Biological Engineers. All rights reserved. ASABE, 2950 Niles Road, St. Joseph, Ml 49085-9659, USA, phone 269-429-0300, fax 269-429-3852, hqasabe.org ANSI/ASAE EP484.2 JUN1998 (R2012

10、) Copyright American Society of Agricultural and Biological Engineers 1 ANSI/ASAE EP484.2 JUN1998 (R2012) Approved August 1998; reaffirmed February 2013 as an American National Standard Diaphragm Design of Metal-Clad, Wood-Frame Rectangular Buildings Developed by the ASAE Diaphragm Design of Metal-C

11、lad, Post-Frame Rectangular Buildings Subcommittee of the Structures Group; approved by the Structures and Environment Division Standards Committee; adopted by ASAE September 1989; revised December 1990; reaffirmed December 1994, 1995, 1996, 1997; revised June 1998; approved as an American National

12、Standard August 1998; revised editorially February 2000; reaffirmed February 2003 by ASAE and ANSI; revised editorially August 2003; reaffirmed by ASABE and ANSI February 2008; reaffirmed by ASABE December 2012, reaffirmed by ANSI February 2013. Keywords: Buildings, Structures, Terminology, Wood-fra

13、me 1 Purpose and Scope 1.1 This Engineering Practice is a consensus document for the analysis and design of metal-clad wood-frame buildings using roof and ceiling diaphragms, alone or in combination. The roof (and ceiling) diaphragms, endwalls, intermediate shearwalls, and building frames are the ma

14、in structural elements of a structural system used to efficiently resist the design lateral (wind) loads. This Engineering Practice gives acceptable methods for analyzing and designing the elements of the diaphragm system. 1.2 The provisions of this Engineering Practice are limited to the analysis o

15、f single-story buildings of rectangular shape. 2 Normative References The following standards contain provisions which, through reference in this text, constitute provisions of this Engineering Practice. At the time of publication, the editions indicated were valid. All standards are subject to revi

16、sion, and parties to agreements based on this Engineering Practice are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Standards organizations maintain registers of currently valid standards. AF see also 3.10. 3.3.4 model diaphragm len

17、gth, b: Length of a model diaphragm as measured parallel to the direction of applied load. 3.3.5 model diaphragm width, a: Length of a model diaphragm as measured perpendicular to the direction of applied load. 3.4 Diaphragm fasteners: The various fasteners and fastener patterns used to connect the

18、several components of the endwalls, shearwalls, and diaphragms. These include fasteners between cladding and purlins, between cladding and endwall girts, between diaphragm framing members, and between individual sheets of cladding (stitch fasteners). 3.5 Diaphragm shear stiffness 3.5.1 model diaphra

19、gm shear stiffness, c: The in-plane shear stiffness of a model diaphragm. Defined as the slope of the shear load-deflection curve between zero load and the load corresponding to the diaphragm allowable shear strength. 3.5.2 in-plane shear stiffness, cp: The in-plane shear stiffness of an individual

20、roof or ceiling diaphragm. 3.5.3 horizontal shear stiffness, ch: The horizontal shear stiffness of an individual roof or ceiling diaphragm. It is obtained by adjusting diaphragm in-plane shear stiffness, cp, for slope. 3.5.4 total horizontal diaphragm shear stiffness, Ch: The horizontal shear stiffn

21、ess of the roof and ceiling assembly is calculated by summing the horizontal shear stiffness values of individual roof and ceiling diaphragms. Alternatively, this stiffness can be obtained from full-scale building tests. 3.6 Diaphragm shear strength, Va: The allowable design shear strength (see ASAE

22、 EP558) of a diaphragm in the plane of the cladding. 3.7 Eave load, R: A concentrated (point) load, horizontally acting, that is located at the eave of each frame, and results in a horizontal eave displacement identical to that caused by application of the controlling combination of design loads. R

23、is numerically equal to the horizontal force required to prevent horizontal translation of the eave when the controlling combination of design loads is applied to the frame. 3.8 Endwall and shearwall stiffness, ke: The ratio of a horizontal force applied at the eave to the corresponding deflection o

24、f an individual unattached wall. A wall is unattached when it is not connected to components that lie outside the plane of the wall. 3.9 Frame stiffness, k: The ratio of a horizontal force applied at the eave to the corresponding deflection of the individual unclad post-frames. 3.10 Frame spacing, s

25、: The distance between frames. In the absence of stiff frames that resist lateral loads, the frame spacing is generally equated to the distance between adjacent trusses (or rafters) or to the model diaphragm width. Frame spacing defines the width (and therefore stiffness properties) of roof/ceiling

26、diaphragm sections. Frame spacing may vary within a building. ANSI/ASAE EP484.2 JUN1998 (R2012) Copyright American Society of Agricultural and Biological Engineers 3 3.11 Metal cladding: The metal exterior and interior coverings, usually cold-formed aluminum or steel sheet, fastened to the wood fram

27、ing. 3.12 Model diaphragm: A laboratory tested diaphragm or a diaphragm analyzed using a validated structural model that is used to predict the behavior of a building diaphragm. Laboratory tested diaphragms should be sized, constructed, supported and tested in accordance with ASAE EP558. 3.13 Post f

28、rame: A structural building frame consisting of a wood roof truss or rafters connected to vertical timber columns, or sidewall posts. 3.14 Sidesway restraining force, Q: The total force applied to a frame by the roof/ceiling diaphragm. 3.15 Shear transfer: The transfer of the resultant shear forces

29、between individual sheets of cladding, between the ends of roof/ceiling diaphragms and frames and shearwalls, or between the bottom of the shearwalls and the base of the posts or foundation. 3.16 Shearwall: An endwall or intermediate wall designed to transfer shear from the roof/ceiling diaphragm in

30、to the foundation structure. 3.17 Wood frame: A structural building frame consisting of wood or wood-based materials. Wood trusses over studwalls and post and beam are examples of wood frames. 4 Diaphragm Stiffness 4.1 General provisions. This section outlines procedures for determining the total ho

31、rizontal shear stiffness, Ch, of a width, s, of the roof/ceiling assembly. This stiffness is defined as the horizontal load required to cause a unit shift (in a direction parallel to the trusses/rafters) of the roof/ceiling assembly over a spacing, s (figure 1). This stiffness can be obtained direct

32、ly from full scale building tests (Gebremedhin et al., 1992), validated structural models, or using procedures outlined in clause 4.2. Figure 1 Definition sketch for terminology ANSI/ASAE EP484.2 JUN1998 (R2012) Copyright American Society of Agricultural and Biological Engineers 4 4.2 Total horizont

33、al shear stiffness, Ch. The total horizontal diaphragm shear stiffness, Ch, for the frame spacing, s, of the roof / ceiling assembly is defined as: =niihhcC1,(1) where: ch,iis horizontal shear stiffness of diaphragm i with a width, s, from clause 4.3, N/mm (lbf/in.); n is number of individual roof a

34、nd ceiling diaphragms in the roof/ceiling assembly (figure 2). When the frame spacing, s, or roof/ceiling diaphragm construction varies along the length of a building, Chmay vary, and the building requires special analysis (see clause 7.3). Figure 2 Building cross section showing four individual dia

35、phragms 4.2.1 Excluding diaphragms. Diaphragm analyses may be simplified by excluding from an analysis any diaphragm that is considerably less stiff than others in the roof/ceiling system. For example, where a ceiling diaphragm is much stiffer than the roof diaphragm(s), the stiffness of the roof di

36、aphragm(s) may be excluded from total stiffness calculations (i.e., equation 1). Nonstructural diaphragms that are framed or attached to a structural frame and/or structural diaphragm in a manner that requires the nonstructural diaphragm to translate with the structural frame and/or structural diaph

37、ragm should not be excluded from the analysis. A nonstructural diaphragm that is relatively stiff is likely to attract more load than it can safely support. 4.3 Horizontal shear stiffness of an individual diaphragm, ch,i. The horizontal shear stiffness of an individual diaphragm can be calculated fr

38、om the diaphragms in-plane shear stiffness (equation 2) or from the in-plane stiffness of a model diaphragm (equation 3). Model diaphragms used to predict the horizontal stiffness of a building diaphragm shall be functionally equivalent to the building diaphragm. ASAE EP558 gives laboratory test pro

39、cedures for obtaining model diaphragm shear stiffness. ANSI/ASAE EP484.2 JUN1998 (R2012) Copyright American Society of Agricultural and Biological Engineers 5 ()iipihcc =2,cos (2) ()()/sbGch,iih,i= cos (3)where: ch,I is horizontal shear stiffness of diaphragm i with width, s, and horizontal span bh,

40、i,N/mm (lbf/in.); cp,iis in-plane shear stiffness of diaphragm i with width, s, and horizontal span bh,i,N/mm (lbf/in.); nullis slope from the horizontal of diaphragm i; G is c (a/b), effective shear modulus; bh,iis horizontal span of diaphragm i as measured parallel to trusses/rafters, m (ft); s is

41、 frame spacing, m (ft); c is in-plane shear stiffness of the model diaphragm, N/mm (lbf/in.); a is length of the model diaphragm as measured perpendicular to the direction of applied load, m (ft); b is depth of the model diaphragm as measured parallel to the direction of applied load, m (ft). 5 Fram

42、e, Endwall, and Shearwall Stiffness 5.1 General provisions. Frames, endwalls, and intermediate shearwalls transfer roof/ceiling loads to the foundation. The amount of load that a frame, endwall, or shearwall attracts is dependent upon its in-plane stiffness. 5.2 Frame stiffness, k. A horizontal forc

43、e, P, applied at the eave of a building frame will result in a horizontal displacement of the eave, (figure 3). The ratio of the force P to the horizontal displacement is defined as the horizontal frame stiffness, k. Frame stiffness is generally obtained with a plane-frame structural analysis progra

44、m, e.g., PPSA (Purdue Research Foundation, 1993), METCLAD (Gebremedhin, 1987b), and SOLVER (Gebremedhin, 1987a). Frame stiffness is equal to zero when all posts in the frame are pin connected to both the truss and the base/foundation. Figure 3 Definition sketch for frame stiffness, k ANSI/ASAE EP484

45、.2 JUN1998 (R2012) Copyright American Society of Agricultural and Biological Engineers 6 5.2.1 Frame stiffness can be calculated using equation 4 when: (1) trusses/rafters are assumed to be pin-connected to the posts, and (2) the base of each post is assumed fixed. ()31/3iniiiHlEk= (4) where: k is f

46、rame stiffness, N/mm (lbf/in.); n is number of posts in the post-frame (normally 2); Eiis modulus of elasticity of post i, N/mm2(lbf/in.2); Iiis moment of inertia of post i, mm4(in.4); Hiis distance from base to pin connection of post i, mm (in.). 5.3 Endwall and shearwall stiffness, ke. Endwall and

47、 shearwall stiffness, like frame stiffness, is defined as the ratio of a horizontal force, P, applied at the eave of the wall, to the resulting horizontal eave displacement, . Endwall and shearwall stiffness can be obtained directly from full scale building tests (Gebremedhin et al, 1992), validated

48、 structural models, or from tests of functionally equivalent assemblies (Gebremedhin and Jorgensen, 1993). ASAE EP558 gives laboratory test procedures that can be used to determine the stiffness of functionally equivalent walls. 6 Eave Loads 6.1 General provisions. In diaphragm analysis, building lo

49、ads are replaced by an equivalent set of horizontally acting, concentrated (i.e., point) loads. These loads are located at the eave of each frame, endwall, and shearwall (i.e., they are spaced a distance, s, apart), and therefore are referred to as eave loads. Eave loads and applied building loads are equivalent when they horizontally displace the eave an equal amount. 6.2 Eave loads, R, by plane-frame structural analysis. A horizontal restraint (vertical roller) is placed at the eave line as shown in figure 4 and the structural