AISC-M019L-1994.pdf
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1、MANUAL AISC MOLSL 94 I OF STEEL CONSTRUCTION f eo w P Q FI o- O O , O w ru b w 0- J I O I LOAD they may be galvanized. Type 3 bolts offer improved atmospheric corrosion resistance and weathering characteristics similar to those of ASTM A242 or A588 steels. ASTM A490 bolts are available in diameters
2、from %-in. to 1 %-in. in two types. Type 1 bolts are alloy-steel bolts. Type 3 are alloy-steel bolts with improved atmospheric corrosion resistance and weathering characteristics similar to those of ASTM A242 or A588 steels. ASTM A490 bolts should not be galvanized and caution should be exercised if
3、 used in highly corrosive environments. Type 2 (martensite) bolts, popular for many years, have been discontinued. Information on this type can be found in previous editions of the AISC Manual of Steel Construction. When bolts of diameter larger than 1 /2 in. are required, ASTM A449 bolts are permit
4、ted to be used for snug-tightened and fully tensioned bearing-type connections; this material is not recognized in LRFD Specification Section A3.3 for use in slip-critical connections nor for use as bolts in diameters not greater than 1% in. ASTM A449 bolts may be galvanized. When an ASTM A449 bolt
5、is used in tension or bearing and is tightened in excess of 50 percent of its minimum specified tensile strength, LRFD Specification Section 53.1 requires that an ASTM F436 washer be installed under the head of the bolt. The nut must be from the approved list in RCSC Specification Section 2(c). Sinc
6、e ASTM A325 nuts and washers for use with high-strength bolts are available only up to l/*-in. diameter, reference should be made to ASTM A563 for nuts and ASTM F436 for washers to select suitable sizes and grades for the intended application. While ASTM A449 seems to be the equal of ASTM A325, ther
7、e are two important differences which should be noted. First, ASTM A449 bolts are not produced to the same inspection and quality assurance requirements as ASTM A325 bolts. Second, ASTM A449 bolts are not produced to the same heavy-hex head and nut dimensions. Alternative Design Bolts RCSC Specifica
8、tion Section 2d permits the use of other fasteners when they meet the requirements as outlined therein. Figure 8- 1 shows a tension-control or “twist-off bolt which is installed with a special tool which twists off the splined end when the proper , f 0- O r U v) H a Fig. 8-1. Tension-control or “twi
9、st-off bolt. AMERICAN INSTITUTE OF STEEL CONSTRLCTION Copyright American Institute of Steel Construction Provided by IHS under license with AISC Licensee=HP Monitoring/1111111164 Not for Resale, 03/05/2009 03:50:00 MSTNo reproduction or networking permitted without license from IHS -,-,- 本文件原文页数较多,文
10、件体积较大,无法上传。 如有需要请发站内信或e m a i l :l i u y x 866163.c o m 联系人:草庐一苇:w w w .d o c i n .c o m /l i u y x 866 8 - 8 BOLTS, WELDS, AND CONNECTED ELEMENTS 3- Q F 3 O Y N a- Y o- -0 O o- 3 O z U L/) H a I galvanized DH D 1 bolt tension is achieved. Tension-control bolts are commonly available to meet the spe
11、cifications of ASTM A325 and A490. Compatible Nuts and Washers The compatibility of ASTM A563 nuts and F436 washers with the aforementioned high-strength bolt specifications is as listed in Table 8- 1. Alternatively, appropriate ASTM A194 nuts may be used. RCSC Specification Section 7c gives general
12、 requirements for when washers are required for high-strength bolts. Economical Considerations Since the material cost per unit of strength of ASTM A490 bolts is comparable with that of ASTM A325 bolts, it might seem more cost effective to reduce the number of bolts in a given connection by specifyi
13、ng ASTM A490 bolts. However, ASTM A490 bolts are more difficult to tighten and raise inventory and quality control issues associated with the use of multiple fastener grades; mixing of ASTM A325 and A490 bolts of the same diameter should be avoided to assure that the ASTM A490 bolts are installed in
14、 the proper location. Thus, the net benefit of specifying ASTM A490 bolts may be less than expected; cost ratios should be considered by the designer. Similarly, cost ratios between grades of alternative design bolts will vary from those of conventional high-strength bolts. Thus, the decision regard
15、ing fastener selection will vary accordingly. Regardless of the bolt type selected, the normal sizes of 3/4-in., /*-in., and 1 -in. diameter are usually preferred. Diameters above one inch are not commonly available, nor are they practical since special tools may be required to achieve fully tension
16、ed installation. Bearing-type connections should be specified whenever possible. Slip-critical connec- tions with coatings other than clean mill scale incur appreciable extra costs associated with blasting, painting, drying, assembling, reblasting, and abrasion touch-up. If slip- critical connection
17、s are required for the proper serviceablity of the structure, care should be taken to avoid requiring the faying surfaces to be masked as this also contributes great AMERICAN INSTITUE OF STEEL CONSTRUCTION Copyright American Institute of Steel Construction Provided by IHS under license with AISC Lic
18、ensee=HP Monitoring/1111111164 Not for Resale, 03/05/2009 03:50:00 MSTNo reproduction or networking permitted without license from IHS -,-,- 本文件原文页数较多,文件体积较大,无法上传。 如有需要请发站内信或e m a i l :l i u y x 866163.c o m 联系人:草庐一苇:w w w .d o c i n .c o m /l i u y x 866 BOLTED CONSTRUCTION m Ob95925 0009202 bL0 8
19、- 9 expense; coatings which provide a Class A or Class B slip coefficient may be an economical alternative to masking. Dimensions and Weights ASTM A325 and A490 bolts, A563 nuts, and F436 washers are given identifying marks as illustrated in Figure 8-2. A detailed description of identifying marks ma
20、y be found in the RCSC Specification. Dimensions of ASTM A325 and A490 bolts, A563 nuts, and F436 washers are given and illustrated in Table 8-2. Threading dimensions of high- strength bolts are given in Table 8-7. Weights of conventional ASTM A325 and A490 bolts, A563 nuts, and F436 washers are giv
21、en in Table 8-3. For dimensions and weights of tension-control ASTM A325 and A490 bolts, refer to manufacturers literature or IFI. For dimensions and weights of ASTM A449 bolts, refer to Table 8-6. Threads for high-strength bolts may be rolled or cut. Note that thread lengths for high-strength bolts
22、 are shorter than those for non-high-strength bolts. This allows the threads to be excluded from the shear plane when the thickness of the connected ply closest to the nut is as shown in Figure 8-3. While the RCSC Specification permits some thread run-out into the shear plane, it is important to pro
23、vide sufficient thread to avoid jamming the nut into the run-out when tightening the bolt. Inspection controversy will be reduced by recognizing that bolts intentionally have a limited thread length, a manufacturing tolerance, and limited length increments; as with all manufactured items, dimensiona
24、l tolerances must be considered. The RCSC Specification recognizes these tolerances in two ways. First, additional washers are permitted to be used under the nut or under the head when circumstances permit. Second, there is no specified bolt “stick-through” requirement since only full- thread engage
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