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1、Construction Building Envelope and Interior Finishes Databook Sidney M. Levy McGraw-Hill New York San Francisco Washington, D.C. Auckland Bogot Caracas Lisbon London Madrid Mexico City Milan Montreal New Delhi San Juan Singapore Sydney Tokyo Toronto 817 Section Metrifi cation Contents 16 16.0.0Intro
2、duction to the 1975 Metric Conversion Act 16.1.0What will change and what will stay the same 16.2.0How metric units will apply in the construction industry 16.3.0 Metrifi cation of pipe sizes 16.4.0 Metrifi cation of standard lumber sizes 16.5.0Metric rebar conversions 16.6.0Metric conversion of AST
3、M diame- ter and wall thickness designations 16.7.0Metric conversion scales (tempera- ture and measurements) 16.8.0Approximate metric conversions 16.9.0Quick imperial (metric equivalents) 16.10.0Metric conversion factors 16.0.0 Introduction to the 1975 Metric Conversion Act As the federal government
4、 moves to convert the inch-pound units to the metric system, in accor- dance with the 1975 Metric Conversion Act, various parts of the construction industry will begin the conversion to this more universal method of measurement. Metric units are often referred to as SI units, an abbreviation taken f
5、rom the French: le Systme International dUnits. Another abbreviation that will be seen with more frequency is ISOthe In- ternational Standards Organization charged with supervising the establishment of a universal stan- dards system. For everyday transactions it may be suffi cient to gain only the b
6、asics of the metric system. Name of metric unitSymbolApproximate size (length/pound) meterm3912inches kilometerkm0.6 mile centimetercmwidth of a paper clip millimetermmthickness of a dime hectareha212acres square meterm21.2 square yards gramgweight of a paper clip kilogramkg2.2 pounds metric tontlon
7、g ton (2240 pounds) literLone quart and two ounces millilitermL 15teaspoon kilopascalkPaatmospheric pressure is about 100 Pa The Celsius temperature scale is used. Instead of referring to its measurement as degree centigrade, the term degree Celsius is the correct designation. Using this term, famil
8、iar points are Water freezes at 0 degrees Water boils at 100 degrees Normal body temperature is 37 degrees (98.6 F) Comfortable room temperature 20 to 35 (68 to 77 F) 16.1.0 What Will Change and What Will Stay the Same? Metric Module and Grid What will change: The basic building module, from 4 inche
9、s to 100 mm. The planning grid, from 2 ? 2 to 600 ? 600 mm. What will stay the same: A module and grid based on rounded, easy-to-use dimensions. The 100 mm module is the global standard. Drawings What will change: Units, from feet and inches to millimeters for all building dimensions and to meters f
10、or site plans and civil engineering drawings. Unit designations are unnecessary: if there is no decimal point, it is millimeters; if there is a decimal point carried to one, two, or three places, it is meters. In ac- cordance with ASTM E621, centimeters are not used in construction because (1) they
11、are not con- 818Section 16 sistent with the preferred use of multiples of 1000, (2) the order of magnitude between a millime- ter and centimeter is only 10 and the use of both units would lead to confusion and require the use of unit designations, and 93) the millimeter is small enough to almost ent
12、irely eliminate decimal fractions from construction documents. Drawing scales, from inch-fractions-to-feet to true rations. Preferred metric scales are: 1:1 (full size) 1:5 (close to 3“ ? 1-0“) 1:10 (between 1“ ? 1-0“ and 112“ ? 1-0“) 1:20 (between 12“ ? 1-0“ and 34“ ? 1-0“) 1:50 (close to 14“ ? 1-0
13、“) 1:100 (close to 18“ ? 1-0“) 1:200 (close to 116“ ? 1-0“) 1:500 (close to 1“ ? 40-0“) 1:1000 (close to 1“ ? 80-0“) As a means of comparison, inch-fraction scales may be converted to true ratios by multiplying a scales divisor by 12; for example, for 14“ ? 1-0“, multiply the 4 by 12 for a true rati
14、o of 1:48. Drawing sizes, to ISO “A” series: A0 (1189 ? 841 mm, 46.8 ? 33.1 inches) A1 (841 ? 594 mm, 33.1 ? 23.4 inches) A2 (594 ? 420 mm, 23.4 ? 16.5 inches) A3 (420 ? 297 mm, 16.5 ? 11.7 inches) A4 (297 ? 210 mm, 11.7 ? 8.3 inches) Of course, metric drawings can be made on any size paper. What wi
15、ll stay the same: Drawing contents Never use dual units (both inch-pound and metric) on drawings. It increases dimensioning time, dou- bles the chance for errors, makes drawings more confusing, and only postpones the learning process. An exception is for construction documents meant to be viewed by
16、the general public. Specifi cations What will change: Units of measure, from feet and inches to millimeters for linear dimensions, from square feet to square meters for area, from cubic yards to cubic meters for volume (except use liters for fl uid vol- umes), and from other inch-pound measures to m
17、etric measures as appropriate. What will stay the same: Everything else in the specifi cations Do not use dual units in specifi cations except when the use of an inch-pound measure serves to clarify an otherwise unfamiliar metric measure; then place the inch-pound unit in parentheses after the metri
18、c. For example, “7.5 kW (10 horsepower) motor.” All unit conversions should be checked by a professional to ensure that rounding does not exceed allowable tolerances. For more information, see the JulyAugust 1994 issue of Metric in Construction. Metrifi cation819 Floor Loads What will change: Floor
19、load designations, from “psf” to kilograms per square meter (kg/m2) for everyday use and kilonewtons per square meter (kN/m2) for structural calculations. What will stay the same: Floor load requirements Kilograms per square meter often are used to designate fl oor loads because many live and dead l
20、oads (furniture, fi ling cabinets, construction materials, etc.) are measured in kilograms. However, kilonewtons per square meter or their equivalent, kilopascals, are the proper measure and should be used in structural calculations. Construction Products What will change: Modular products: brick, b
21、lock, drywall, plywood, suspended ceiling systems, and raised fl oor sys- tems. They will undergo “hard” conversion; that is, their dimensions will change to fi t the 100 mm module. Products that are custom-fabricated or formed for each job (for example, cabinets, stairs, handrails, ductwork, commer
22、cial doors and windows, structural steel systems, and concrete work). Such products usually can be made in any size, inch-pound or metric, with equal ease; therefore, for metric jobs, they simply will be fabricated or formed in metric. What will stay the same: All other products, since they are cut-
23、to-fi t at the jobsite (for example, framing lumber, woodwork, siding, wiring, piping, and roofi ng) or are not dimensionally sensitive (for example, fasteners, hard- ware, electrical components, plumbing fi xtures, and HVAC equipment). Such products will just be “soft” convertedthat is, relabeled i
24、n metric units. A 234“ ? 412“ wall switch face plate will be rela- beled 70 ? 115 mm and a 30 gallon tank, 114 L. Manufacturers eventually may convert the physi- cal dimensions of many of these products to new rational “hard” metric sizes but only when it be- comes convenient for them to do so. “2-B
25、y-4” Studs and Other “2-By” Framing (Both Wood and Metal) What will change: Spacing, from 16“ to 400 mm, and 24” to 600 mm. What will stay the same: Everything else. “2-bys” are produced in “soft” fractional inch dimensions so there is no need to convert them to new rounded “hard” metric dimensions.
26、 2-by-4s may keep their traditional name or perhaps they will eventually be renamed 50 by 100 (mm), or, more exactly, 38 ? 39. Drywall, Plywood, and Other Sheet Goods What will change: Widths, from 40“ to 1200 mm. Heights, from 8-0“ to 2400 mm, 10-0“ to 3000 mm. 820Section 16 What will stay the same
27、: Thicknesses, so fi re, acoustic, and thermal ratings will not have to be recalculated. Metric drywall and plywood are readily available but may require longer lead times for ordering and may cost more in small amounts until their use becomes more common. Batt Insulation What will change: Nominal w
28、idth labels, from 16“ to 16“/400 mm and 24“ to 24“/600 mm. What will stay the same: Everything else. Batts will not change in width, they will just have a tighter “friction fi t” when installed between metric-spaced framing members. Doors What will change: Height, from 6-8“ to 2050 mm or 2100 mm and
29、 from 7-0“ to 2100 mm. Width, from 2-6“ to 750 mm, from 2-8“ to 800 mm, from 2-10“ to 850 mm, from 3“-0“ to 900 mm or 950 mm, and from 3-4“ to 1000 mm. What will stay the same: Door thicknesses. Door materials and hardware. For commercial work, doors and door frames can be ordered in any size since
30、they normally are custom-fabricated. Ceiling Systems What will change: Grids and lay-in ceiling tile, air diffusers and recessed lighting fi xtures, from 2 ? 2 to 600 ? 600 mm and from 2 ? 4 to 600 ? 1200 mm. What will stay the same: Grid profi les, tile thicknesses, air diffuser capacities, fl uore
31、scent tubes, and means of suspension. On federal building projects, metric recessed lighting fi xtures may be specifi ed if their total in- stalled costs are estimated to be more than for inch-pound fi xtures. Raised Floor Systems What will change: Grids and lay-in fl oor tile, from 2 ? 2 to 600 ? 6
32、00 mm. What will stay the same: Grid profi les, tile thicknesses, and means of support. Metrifi cation821 HVAC Controls What will change: Temperature units, from Fahrenheit to Celsius. What will stay the same: All other parts of the controls. Controls are now digital so temperature conversions can b
33、e made with no diffi culty. Brick What will change: Standard brick, to 90 ? 57 ? 190 mm. Mortar joints, from 38“ and 12“ to 10 mm. Brick module, from 2 ? 2 to 600 ? 600 mm. What will stay the same: Brick and mortar composition. Of the 100 or so brick sizes currently made, 5 to 10 are within a millim
34、eter of a metric brick so the brick industry will have no trouble supplying metric brick. For more information, see the MarchApril 1995 issue of Metric in Construction. Concrete Block What will change: Block sizes, to 190 ? 190 ? 390 mm. Mortar joints, from 12“ to 10 mm. Block module, from 2 ? 2 to
35、600 ? 600 mm. What will stay the same: Block and mortar composition. On federal building projects, metric block may be specifi ed if its total installed cost is estimated to be more than for inch-pound block. The Construction Metrication Council recommends that, wher- ever possible, block walls be d
36、esigned and specifi ed in a manner that permits the use of either inch- pound or metric block, allowing the fi nal decision to be made by the contractor. Sheet Metal What will change: Designation, from “gage” to millimeters. What will stay the same: Thickness, which will be soft-converted to tenths
37、of a millimeter. In specifi cations, use millimeters only or millimeters with the gage in parentheses. 822Section 16 Concrete What will change: Strength designations, from “psi” to megapascals, rounded to the nearest 5 megapascals per ACI 318M as follows: 2500 psi to 20 MPa 3000 psi to 25 MPa 3500 p
38、si to 25 MPa 4000 psi to 30 MPa 4500 psi to 35 MPa 5000 psi to 35 MPa Depending on exact usage, however, the above metric conversions may be more exact than those indicated. What will stay the same: Everything else. For more information, see the NovemberDecember 1994 issue of Metric in Construction.
39、 Rebar What will change: Rebar will not change in size but will be renamed per ASTM A615M-96a and ASTM A706M-96a as follows: No. 3 to No. 10No. 9 to No. 29 No. 4 to No. 13No. 10 to No. 32 No. 5 to No. 16No. 11 to No. 36 No. 6 to No. 19No. 14 to No. 43 No. 7 to No. 22No. 18 to No. 57 No. 8 to No. 25
40、What will stay the same: Everything else. For more information, see the JulyAugust 1996 issue of Metric on Construction. Glass What will change: Nominal pipe and fi tting designations, from inches to millimeters. What will stay the same: Pipe and fi tting cross sections and threads. Pipes and fi tti
41、ngs are produced in “soft” decimal-inch dimensions but are identifi ed in nominal- inch sizes as a matter of convenience. A 2-inch pipe has neither an inside nor an outside diameter of Metrifi cation823 2 inches, a 1-inch fi tting has no exact 1-inch dimension, and a 12-inch sprinkler head contains
42、no 12- inch dimension anywhere; consequently, there is no need to “hard” convert pipes and fi ttings to rounded metric dimensions. Instead, they will not change size but simply be relabeled in metric as follows: 18“ ? 6 mm 112“ ? 40 mm 316“ ? 7 mm 2“ ? 50 mm 14“ ? 8 mm 212“ ? 65 mm 38“ ? 10 mm 3“ ?
43、75 mm 12“ ? 15 mm 312“ ? 90 mm 58“ ? 18 mm 4“ ? 100 mm 34“ ? 20 mm 412“ ? 115 mm 1“ ? 25 mm1“ ? 25 mm for all larger sizes 114“ ? 32 mm For more information, see the SeptemberOctober 1993 issue of Metric in Construction. Electrical Conduit What will change: Nominal conduit designations, from inches
44、to millimeters. What will stay the same: Conduit cross sections. Electrical conduit is similar to piping: it is produced in “soft” decimal-inch dimensions but is iden- tifi ed in nominal-inch sizes. Neither metallic nor nonmetallic conduit will change size; they will be re- labeled in metric units a
45、s follows: 12“ ? 16 (mm) 212“ ? 63 (mm) 34“ ? 21 (mm) 3“ ? 78 (mm) 1“ ? 27 (mm)312“ ? 91 (mm) 114“ ? 35 (mm)4“ ? 103 (mm) 112“ ? 41 (mm)5“ ? 129 (mm) 2“ ? 53 (mm)6“ ? 155 (mm) These new metric names were assigned by the National Electrical Manufacturers Association. Electrical Wire What will change:
46、 Nothing at this time. What will stay the same: Existing American Wire Gage (AWG) sizes. Structural Steel What will change: Section designations, from inches to millimeters and from pounds per foot to kilograms per meter, in accordance with ASTM A6M. 824Section 16 Boltsto metric diameters and thread
47、s per ASTM A325M and A490M. What will stay the same: Cross sections. Like pipe and conduit, steel sections are produced in “soft” decimal-inch dimensions (with actual depths varying by weight) but are named in rounded-inch dimensions so there is no need to “hard” convert them to metric units. Rather
48、, their names will be changed to metric designations, and rounded to the nearest 10 mm. Thus, a 10-inch section is relabeled as a 250-mm section and a 24- inch section is relabeled as a 610-mm section. Metrifi cation825 16.2.0 How Metric Units Will Apply in the Construction Industry 826Section 16 16
49、.3.0 Metrifi cation of Pipe Sizes Pipe diameter sizes can be confusing because their designated size does not correspond to their ac- tual size. For instance, a 2-inch steel pipe has an inside diameter of approximately 218inches and an outside diameter of about 258inches. The 2 inch designation is very similar to the 2“ ? 4“ designation for wood studs, neither dimen- sions are “actual,” but they ar