参考一下美规
Specification for Structural Joints Using ASTM A325 or A490 Bolts, June 23, 2000
RESEARCH COUNCIL ON STRUCTURAL CONNECTIONS
3.2. Faying Surfaces
Faying surfaces and surfaces adjacent to the bolt head and nut shall be free of dirt
and other foreign material. Additionally, faying surfaces shall meet the
requirements in Sections 3.2.1 or 3.2.2.
3.2.1. Snug-Tightened Joints and Pretensioned Joints: The faying surfaces of snugtightened
joints and pretensioned joints as defined in Sections 4.1 and 4.2 are
permitted to be uncoated, coated with coatings of any formulation or galvanized.
Commentary:
In both snug-tightened joints and pretensioned joints, the ultimate strength is
dependent upon shear transmitted by the bolts and bearing of the bolts against the
connected material. It is independent of any frictional resistance that may exist on
the faying surfaces. Consequently, since slip resistance is not an issue, the faying
surfaces are permitted to be uncoated, coated, or galvanized without regard to the
resulting slip coefficient obtained.
3.2.2. Slip-Critical Joints: The faying surfaces of slip-critical joints as defined in Section
4.3, including those of filler plates and finger shims, shall meet the following
requirements:
(a) Uncoated Faying Surfaces: Uncoated faying surfaces shall be free of scale,
except tight mill scale, and free of coatings, including inadvertent overspray,
in areas closer than one bolt diameter but not less than 1 in. from the edge
of any hole and in all areas within the bolt pattern.
(b) Coated Faying Surfaces: Coated faying surfaces shall first be blast cleaned
and subsequently coated with a coating that is qualified in accordance with
the requirements in Appendix A as a Class A or Class B coating as defined
in Section 5.4. Alternatively, when approved by the Engineer of Record,
coatings that provide a mean slip coefficient that differs from Class A or
Class B are permitted when:
(1) The mean slip coefficient [$micro] is established by testing in accordance with
the requirements in Appendix A; and,
(2) The design slip resistance is determined in accordance with Section
5.4 using this coefficient, except that, for design purposes, a value of [$micro]
greater than 0.50 shall not be used.
The plies of slip-critical joints with coated faying surfaces shall not be
assembled before the coating has cured for the minimum time that was used
in the qualifying tests.
(c) Galvanized Faying Surfaces: Galvanized faying surfaces shall first be hotdip
galvanized in accordance with the requirements of ASTM A123 and
subsequently roughened by means of hand wire brushing. Power wire
brushing is not permitted. When prepared by roughening, the galvanized
faying surface is designated as Class C for design.
3.2.1节中对承压型高强度螺栓对磨擦面规定的最后一句:
Consequently, since slip resistance is not an issue, the faying
surfaces are permitted to be uncoated, coated, or galvanized without regard to the resulting slip coefficient obtained.
显然磨擦面可以是不油漆,油漆和镀锌三种。没有强制规定一定要用哪一种。承载力都一样。
3.2.2节中对磨擦型高强度螺栓磨擦面规定.也是三种都可以用,只是承载力不一样。对涂漆面还有一些特别的规定。