1、15Steel Design Guide SeriesAISC Rehabilitation and Retrofit GuideA Reference for Historic Shapes and SpecificationsRoger L. Brockenbrough, PER. L. Brockenbrough A500 Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes; and A501 Hot-Formed Welded and Seamless Carbon St
2、eel Structural Tubing. The 1978 AISC Specification added a fourth standard, A618 Hot-Formed Welded and Seamless High-Strength Low-Alloy Structural Tubing. All four standards are included in current AISC specifications. A500, A501, and A618 all include both round and shaped (usually square and rectan
3、gular) HSS. The only standard referenced by AISC for steel pipe, A53, was first published in 1915. Only Grade B is included in the AISC specifications. A500, which is for cold-formed carbon steel product, was first published in 1964 and included two grades for round HSS and two for shaped HSS. Two m
4、ore grades of each were added subsequently. A501, which is for hot-formed carbon steel product, was first published in 1964 and includes only one strength level. A618, which is for hot-formed HSLA product, was first published in 1968 and includes three strength levels. As with other steel products,
5、it is important to properly identify the material when investigating existing construction with steel pipe or HSS. For example, A53 steel pipe has a specified minimum yield point of 35 ksi, while round HSS can have a specified minimum yield point of 33 to 50 ksi, depending upon specification and gra
6、de. A summary of ASTM standards for steel pipe and HSS is provided in Table 1.2. 21.3 Hot-Driven Rivets Through at least 1949, A141 specified the yield point and tensile strength of rivet steel, as indicated in Table 1.1a. For many years now, however, rivets standards have specified the material har
7、dness instead. Hardness is generally related to tensile strength as indicated by tables in ASTM A370. All material requirements refer to the un-driven rivet. The 1963 AISC Specification included three ASTM standards for rivet steel: A141 Structural Rivet Steel, A195 High-Strength Rivet Steel, and A4
8、06 High-Strength Structural Alloy Rivet Steel. A195 and A406 were introduced for use with the higher-strength steels that were included in the AISC Specification at that time. A406 was discontinued in 1965 without replacement. A141 was discontinued in 1967 and replaced by A502. A195 was also discont
9、inued in the 1960s. The 1969 AISC Specification included only A502, Grade 1 or Grade 2, Specification for Structural Rivets. The A502 specification was originally published in 1964, combining and including previous discontinued rivet steel specifications (A141 and A195). The 1978 AISC Specification
10、and subsequent editions have included A502 Grades 1, 2, and 3. A502-93 defined three grades, with Grades 2 and 3 as the higher-hardness (higher-strength) grades. Grade 3 has enhanced atmospheric corrosion with resistance to weathering comparable to that of A588/A588M steel. Hardness values specified
11、 in A502 are listed in Table 1.3a. In 1999, A502-93 was discontinued without replacement. Allowable stresses for hot-driven rivets as specified by AISC over the years are summarized in Table 1.3b. Design strengths according to AISC LRFD specifications are given in Table 1.3c. The latter must be used
12、 in conjunction with factored loads. Certain strength reductions for long connections may apply. Also, the combined effects of tension and shear must be considered where both are present. Other design limitations may apply. Stress calculations are always based on the nominal body area before driving
13、, even though the area after driving will often be greater. 1.4 Structural Bolts Two general types of bolts have been commonly used for structural steel connections: carbon steel bolts (A307) and high-strength bolts (A325, A354BC, A449, A490, and F1852). Information on each is given in the following
14、 sections. Further details on the historical development of high-strength bolted joints is given in Appendix A2. 1.4.1 Carbon Steel Bolts In the 1949 AISC Specification, the term unfinished bolts was used to refer to carbon steel bolts. In the 1969 and subsequent specifications, reference has been m
15、ade to A307 bolts. The A307 standard was first published in 1947. These bolts have a tensile strength of 60 ksi and are not installed with pretension. Allowable stresses from AISC specifications over the years are given in Table 1.4.1a. Design strengths according to AISC LRFD specifications are give
16、n in Table 1.4.1b. The latter must be used in conjunction with factored loads. Allowable bearing stresses are the same as for rivets, Tables 1.3b and 1.3c. Certain strength reductions for long connections may apply. Also, the combined effects of tension and shear must be considered where both are pr
17、esent. Bearing and other design limitations may apply. 1.4.2 High-Strength Steel Bolts High-strength bolts were first used in the United States after World War II to replace rivets in the maintenance of railroad bridges. The Research Council on Riveted and Bolted Structural Joints (RCRBSJ) developed
18、 the first specification for the design of connections with high-strength bolts in 1951. It identified the ASTM A325 high-strength bolt as equivalent to a hot driven ASTM 141 rivet. Numerous new editions of the specifications have been developed over the years by the RCRBSJ and its 1980 successor, t
19、he Research Council on Steel Connections (RCSC). A summary of the salient points of those specifications is given in Appendix A2. High-strength bolts were initially recognized in the 1961 AISC Specification. High-strength bolts that have been used for structural connections include A325, A354 Grade
20、BC, A449, and A490 bolts. Standards 3A325, A449, and A490 were first published in 1964, and the standard for A354 in 1952. Tensile properties of these bolts are as listed in Table 1.4.2a. Twist-off-type tension-control fastener assemblies (i.e., splined-ended bolt assemblies with nuts and washers) w
21、ith properties similar to A325 bolts, were standardized in 1998 as F1852. These so-called TC bolts had been used for several years previously as A325 equivalents. Similar TC equivalents have also been used for A490 bolts. Compressible-washer-type direct tension indicators, which depend on measuremen
22、t of a gap at the washer for tension control, can be furnished to F959. It is important that appropriate nuts and washers are used with high-strength bolts. Table 1.4.2b lists acceptable types. Bolt types for A325 are as follows: Type 1 medium-carbon, carbon-boron, or alloy steel, quenched and tempe
23、red, Type 2 low-carbon martensite steel, quenched and tempered, and Type 3 weathering steel, quenched and tempered. Type 2 was withdrawn in 1991. Bolt types for A490 are as follows: Type 1 alloy steel, quenched and tempered, Type 2 low-carbon martensite steel, quenched and tempered, and Type 3 weath
24、ering steel, quenched and tempered. Type 2 was withdrawn circa 1994. Bolt types for A449 are as follows: Type 1 medium carbon, Type 2 low-carbon martensite or medium-carbon martensite steel, quenched and tempered. Allowable stresses for high-strength bolts that have been given in RCRBSJ/RCSC specifi
25、cations since first issued are given in Table 1.4.2c. These allowable stresses are usually adopted in AISC specifications as they are updated. Similarly, design strengths for LRFD specifications are given in Table 1.4.2d. The latter must be used in conjunction with factored loads, except that slip-c
26、ritical connections can be checked at service loads under some conditions. Certain strength reductions for long connections may apply. Also, the combined effects of tension and shear must be considered where both are present. Other design limitations including fatigue may apply. Hole configuration m
27、ust be considered for slip-critical connections. 1.5 Structural Welding Allowable stresses for welds that have been given by AISC manuals and specifications since the first introduction of welding in 1934 are given in Table 1.5.b. Design strengths for LRFD specifications are given in Table 1.5c. The
28、 latter must be used in conjunction with factored loads. Further details on the historical development of specifications for welding in AISC is given in Appendix A3. 4Table 1.1a Historical Summary of ASTM Specifications for Structural Shapes and Plates Date Specification Material Yield Point, ksi Te
29、nsile Strength,ksi 1900 A7 for Bridges A9 for Buildings Rivet Steel Soft Steel Medium Steel Rivet Steel Medium Steel 30 32 35 30 35 50/60 52/62 60/70 50/60 60/70 1901-1904 A7 for Bridges A9 for Buildings Rivet Steel Soft Steel Medium Steel Rivet Steel Medium Steel Tensile Str. Tensile Str. Tensile S
30、tr. Tensile Str. Tensile Str. 50/60 52/62 60/70 50/60 60/70 1905-1908 A7 for Bridges A9 for Buildings Structural Steel Rivet Steel Steel Castings Rivet Steel Medium Steel Record Value Record Value Tensile Str. Tensile Str. Tensile Str. 60 desired 50 desired 65 50/60 60/70 1909-1913 A7 for Bridges A9
31、 for Buildings Structural Steel Rivet Steel Steel Castings* *Deleted 1913. Structural Steel Rivet Steel Record Value Record Value Tensile Str. Tensile Str. Tensile Str. 60 desired 50 desired 65 55/65 48/58 1914-1923 A7 for Bridges A9 for Buildings Structural Steel Rivet Steel Structural Steel Rivet
32、Steel Tensile Str. Tensile Str. Tensile Str. Tensile Str. 55/65 46/56 55/65 46/56 1924-1931 A7 for Bridges A9 for Buildings Structural Steel Rivet Steel Structural Steel Rivet Steel Tensile Str. 30 Tensile Str. 25 Tensile Str. 30 Tensile Str. 25 55/65 46/56 55/65 46/56 5Table 1.1a (Contd.) Historica
33、l Summary of ASTM Specifications for Structural Steel Date Specification Material Yield Point, ksi Tensile Strength,ksi 1932 A140-32T* * Issued as a tentative revision to A7 and A9. A141-32T* * Issued as a tentative revision to A7 and A9. Plates, Shapes, plain DH; galvanized and lubricated C3 and DH
34、3; plain 1; plain 1; galvanized 3; plain A1852 1 3 Plain (uncoated) Mechanically galvanized Plain C, C3, D, DH and DH3; plain DH; mech. galvanized and lubricated C3 and DH3; plain 1; plain 1; mech. galvanized 3; plain A490 1 3 Plain Plain DH and DH3; plain DH3; plain 1; plain 3; plain * Based on cur
35、rent RCSC specifications, which should be referred to for complete details. The substitution of A194 grade 2H nuts in place of A563 grade DH nuts is permitted. F959 direct tension indicator washers are permitted with A325 and A490 bolts.18Table 1.4.2c Historical RCSC Allowable Stresses (ksi) for Hig
36、h-Strength Bolts ASD* RCSC Date Bolt Type Tension Shear, Slip-Critical Type Shear, Bearing Type, Threads Incl. Shear, Bearing Type, Threads Excl. Bearing 1951 A325 20 15 15 15 32/401960 A325 40 15 15 22 46 1962 A325 A354BC* 40 50 15 20 15 20 22 24 45 45 1964 A325 A490 40 60 15 22.5 15 22.5 22 32 1.3
37、5 Fy 1.35 Fy1966 A325 A490 40 54 15 20 15 22.5 22 32 1.35 Fy 1.35 Fy1976 A325 A490 44 54 17.5* 22* 21 28 30 40 1.50 Fu 1.50 Fu1985 A325 Cl. A surf. Cl. B surf. Cl. C surf. A490 Cl. A surf. Cl. B surf. Cl. C surf. 44 44 44 54 54 54 17 28 22 21 34 27 21 21 21 28 28 28 30 30 30 40 40 40 1.20 Fu where d
38、eformation is a consideration; otherwise, 1.50 Fu1994 Unchanged. 2000 A325 A490 44 54 Varies with bolt pretension and surface condition. 21 30 30 40 1.20 Fu where deformation is a consideration; otherwise, 1.50 Fu* Stress on nominal body area. * Stresses per AISC Specification; not included in RCSC.
39、 * Values vary for surface conditions. Lower value for single shear, larger value for double shear. 19Table 1.4.2d Historical RCSC Design Strengths (ksi) for High-Strength Bolts LRFD* RCSC Date Bolt Type Tension Shear, Slip-Critical Type* Shear, Bearing Type, Threads Incl. Shear, Bearing Type, Threa
40、ds Excl. Bearing 1988 A325 Cl. A surf. Cl. B surf. Cl. C surf. A490 Cl. A surf. Cl. B surf. Cl. C surf. 0.75x90= 67.5 67.5 67.5 0.75x113= 85 85 85 17 28 22 21 34 27 0.75x48= 36 36 36 0.75x60= 45 45 45 0.75x60= 45 45 45 0.75x75= 56 56 56 0.75x2.4Fu= 1.80 Fu 1.80 Fu 1.80 Fu 0.75x2.4Fu=1.80 Fu 1.80 Fu
41、1.80 Fu1994 A325 A490 0.75x90=67.5 0.75x113=85 Varies with bolt pretension and surface condition. 0.75x48=36 0.75x60=45 0.75x60=45 0.75x75=56 0.75x2.4Fu= 1.80 Fu where deformation is a consideration; otherwise, 0.75x3.0Fu=2.25 Fu2000 Unchanged. * Stress on nominal body area. * Based on = 1.0, slip p
42、robability = 0.81, and slip coefficient = 0.33, Class A surface. 20Table 1.5a Historical AISC Allowable Stresses (ksi) for Welds - ASD Year Source Steels and Welding Materials Fillet Weld Shear Tension Compression 1934 AISC Manual A7/A9 steel 11.3 13 15 1939 AISC Manual A7/A9 steel 11.3 13 18 1946 A
43、ISC Spec. A7/A9 steel: 60xx electrodes. 13.6 20 20 1961, 1963 AISC Spec. All steels: 60xx electrodes or subarc Grade SAW-1. A7 and A373 steels: 70xx or subarc Grade SAW-2. A36, A242, and A441 steels: 70xx or subarc Grade SAW-2. 13.6 13.6 15.8 Same as member, all cases. Same as member, all cases. 196
44、9 AISC Spec. All steels and weld processes.* 0.30Fuw“ “ 1989 AISC Spec. No significant changes. 0.30Fuw“ “ * 13.0 for shear in butt welds. * Electrodes and matching base metals are defined. Allowable shear stress is 0.30 times nominal tensile strength of weld metal, 0.30Fuw. Supplement 3, 1974, perm
45、itted weld metal with a strength level equal to or less than matching base metal, except for tension members. Table 1.5b Historical AISC Design Strengths (Fwor FBM, ksi) for Welds - LRFD Year Source Steels and Welding Materials Fillet Weld Shear CJP Groove Weld in Tension CJP Groove Weld in Compress
46、ion 1986 AISC Spec. All 0.75x0.60FEXX = 0.45 FEXX0.90 Fy0.90 Fy1993 AISC Spec. “ “ “ “ 1999 AISC Spec. “ “ “ “ Symbols: Fw= Nominal strength of weld electrode material, ksi FBM= Nominal strength of base metal, ksi FEXX = Classification number weld metal (minimum specified strength), ksi Fy= Specifie
47、d minimum yield stress of steel being welded, ksi Chapter 2PROPERTIES OF DISCONTINUED BEAMS ANDCOLUMNS 1873-2000For Steel Sections 1971-2000 (Section 2.1) andSteel Sections 1953-1970 (Section 2.2), thefollowing properties were taken from old AISCManuals, or calculated where missing.For Steel Section
48、s 1887-1952 (Section 2.3)and Wrought Iron Sections 1873-1900 (Section2.4), the properties were taken from Iron andSteel Beams -1873 to 1952, or calculated wheremissing. Thus, the format differs somewhat fromthat for the sections taken from the AISCManuals. The depth, web thickness, flangewidth, and
49、flange thickness are shown only asdecimal values. Dimensions T, k, and areshown as decimals rather than fractions.For Steel Sections 1887-1952 (Section 2.3),the “Designation“ for 14 sections are shown as “-“. These were sections have no knowndesignation. For Wrought Iron Sections 1873-1900 (Section 2.4), the “Designation“ is simplyshown as a sequential number from 1 to 295 asthey have and have no known designation.2.1 Steel Sections 1971-2000The following information can be found inTa
