CRSI / Engineering Data Report\Number 42 - Using Soft Metric Reinforcing Bars in Non-Metric Construction Projects (Concrete Reinforcing Steel Institute)

TABLE 3 ASTM Specifications - Bar Sizes, Grade, and Tensile and Bending Properties

Type of Steel and ASTM Specification	Bar Sizes	Grade	Minimum Yield Strength MPa [psi]	Minimum Tensile Strength MPa [psi]	Minimum Percentage of Elongation in 203.2 mm [8 in.]	Cold Bend Test Pin Diameter (d= nominal diameter of bar)
Billet-Steel A615/A615M-96a	#10 - #19 [#3 - #6]	300 [40]	300 [40,000]	500 [70,000]	#10 [#3] ...11 #13,#16,#19 [#4, # 5, # 6]...12	#10,#13,#16 [#3, #4, #5]...3.5d #19 [#6]...5d
	#10-#36, #43, #57 [#3-#11, #14, #18]	420 [60]	420 [60,000]	620 [90,000]	#10, #13, #16, #19 [#3, #4, #5, #6]...9 #22, #25 [#7, #8]...8 #29,#32,#36,#43,#57 [#9, #10, #11, #14, #18]...7	#10,#13,#16 [#3, #4, #5] ...3.5d #19,#22,#25 [#6, #7, #8] ...5d #29,#32,#36 [#9, #10,#11] ...7d #43, #57 (90°) [# 14, # 18 (90°)] ...9d
	#19-#36, #43, #57 [#6-#11, #14, #18]	520 [75]	520 [75,000]	690 [100,000]	#19,#22,#25 [#6, #7, #8]...7 #29, #32, #36, #43, #57 [#9, # 10, # 11, #14, #18]...6	#19,#22,#25 [#6, #7, #8] ...5d #29,#32,#36 [#9,#10, #11] ...7d #43, #57 (90°) [# 14, # 18 (90°)] ...9d
Low-Alloy Steel A706/A706M-96b	#10-#36,#43,#57 [#3-#11, #14, #18]	420 [60]	420 [60,000]	550 [80,000]	#10,#13,#16,#19 [#3, #4, 95, #6]...14 #22,#25,#29,#32,#36 [#7, #8, #9, #10, # 11]...12 #43,#57 [#14, #18]...10	#10,#13,#16 [#3, #4, #5]...3d #19,#22,#25 [#6,#7,#8]...4d #29,#32,#36 [#9, # 10, #11]...6d #43, #57 [#14,# 18]...8d

Bar sizes and other data enclosed within brackets are for inch-pound bars.
For low-alloy steel rebars, ASTM A706/A706M-96b prescribes a maximum yield strength of 540 MPa [78,000 psi] and tensile strength must be 1.25 times the actual yield strength.
Bend tests are 180° except ASTM A61 5/A61 5M-95a permits 90° for bar sizes #43 and #57 [#14 and #18].

CRSI recommends minimizing manual arc welding of reinforcing bars in the field, wherever possible.^{^††} Consider mechanical splices as an alternative to welded splices of rebars. However, if a project requires welded splices, the Architect/Engineer should specify the welding to conform to the requirements of the ANS/AWS D1.4 Welding Code, should consider specifying low-alloy steel bars, and so forth. With regard to the thrust of this report, the adoption of the soft metric bar sizes and their complete interchangeability with corresponding sizes and strength levels of inch-pound bars, is also advantageous to welded splices.

Concrete Cover. The architectural/engineering community, government agencies, building officials, detailers; and contractors have raised questions regarding the use of current inch-pound dimensioned bar supports and side form spacers for metric construction projects, and the compatibility of the accessories with soft metric reinforcing bars in providing the minimum concrete cover required.

For cast-in-place construction, ACI 318M-95 prescribes minimum concrete covers of 20, 40, 50 and 70 millimeters(mm). The latter value applies to concrete cast against earth.

Table 4 shows the minimum concrete covers mandated in ACI 318M-95 and their equivalent values in inches. Also included in Table 4 are the nominal heights of commercially-available bar supports in inches, and their equivalent heights in millimeters. The inch-pound bar supports with nominal heights of % in., 1-Y2 in., and 2 in. will provide the required minimum concrete covers of 20 mm, 40 mm, and 50 mm, respectively.

Table 4 Minimum Concrete Cover per ACI 318M-95 and Nominal Heights of Bar Supports

Minimum Concrete Cover		Nominal Heights of Bar Supports
mm	Equivalent, in.	in.	Equivalent, mm
20 40 50 70	0.79 1.58 1.97 2.76	3/4 1 -1/2 2 3	19 38 51 76

^†† CRSI Manual of Standard Practice, 26th Ed., 1997.

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