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Structural. Welding the nut to an A325 grade bolt is a definite "no-no". The use of locking nuts,double jam nuts, lok-tite are all good options, but I would agree with Taro's post regarding the welding. As a footnote, I personally avoid (fatal as you put it)tension only connections wherever possible.
Personally I would not allow the substitution without a written change order from EOR because of two words in your reply, "pedestrian and bridge". Normally B7 bolts aren't galvanized while A325's are. The 325's have a very definate product form with a specific length of threads to shank length, which isn't normally found in B7s'.
The strength properties of SAE J429 grade 5 bolts and ASTM A325 bolts are identical; likewise, SAE J429 grade 8 bolts are the strength equivalent of ASTM A490 bolts. These material specifications differ, however, in that ASTM A325 and A490 specify thread length and head size, whereas SAE J429 does not.
ASTM A325 type 1 bolts are medium carbon, carbon/boron or low carbon steel, quenched and tempered. Elongation in 4D is 14% min and reduction in area is 35% min. SAE J429 grade 5 is typically paired with ASTM A449. These bolts are also medium carbon steel, quenched and tempered, with 14% min RA and 35% elongation.
1 Mar 19 20:35. According to the ASTM, A325 bolts come in two minimum tensile strengths: 120 ksi for 1" diameter and below, and 105 ksi for anything over 1" diameter. Yet the steel construction manual Table 7-1 gives the same Fnv value regardless of bolt diameter. If I understand correctly, Fnv=0.45Fu (threads not excluded), so what am I missing?
This connection has been prototyped with a rivet similar to the Hollo-bolts that connectegr described, but we are unsatisfied with the clamping force of the fasteners, which slip exceeding our tolerance requirements. It is our hope to use A325 bolts in some fashion to give us a greater clamping force.
Problems with Galvanized A325 bolts AlwaysAnAggie (Structural) (OP) 1 Mar 11 14:14.
The S-W device is a hydraulic load cell that allows you to place a bolt and nut sample directly into the device and tighten the bolt with a torque wrench. As the bolt is tightened, the tension is the bolt shows on a gage on the S-W device. The scale on the gage is marked by bolt size and tension.
Mechanical. A325 Type 1 calls for medium carbon, Q&T steel, type 2 low carbon martensitic Q&T steel. For both, min yield 81 ksi, min. ultimate 105 ksi. Because the spec. is limited to 1.5" max. diameter, there is some question about what strength the application really requires - i.e. in ASTM A449, which is also a medium carbon Q&T bolt ...
JAE - Here is a lead from a paper about A325 & A490 bolts on the website of the National Science Foundation, Network for Earthquake Engineering Simulation: Although bolts aren’t typically designed for bending, bending stresses are. often present due to misalignment, non-perpendicular holes, joint prying and other.