Dinosaur
Structural
- Mar 14, 2002
- 538
Folks,
As my handle indicates, I work in a "working stress" state and the majority of my experience is in using working stress design methods. Recently I was asked to check some bolted field splice calcs for a steel girder bridge. The designer performed the usual checks on the bolts calculating the force on the critical bolt and checked that against the LFD values for a slip-critical bolt in the AASHTO Standard Specs (e.g. a Type F bolt in AISC nomenclature). However, when he checked the "75%" criteria in accordance with (I think it is) Article 10.18.2 he divided that by the capacity of a bolt bearing against material (e.g. a Type N bolt in AISC nomenclature). I told him he should use the Type F bolt limit for all checks regarding bolted field splices. He showed my an example in an AASHTO commentary that used the Type N values for the "75%" strength limit check and said this was what he was using. Anybody want to weigh in on this? I have always used the Type F limits for bolt performance because the code the splices must be designed as slip critical; therefore, the Type N (or Type X) limits have no meaning in this problem; you have to meet the Type F by my understanding. Thanks. - Dinosaur
As my handle indicates, I work in a "working stress" state and the majority of my experience is in using working stress design methods. Recently I was asked to check some bolted field splice calcs for a steel girder bridge. The designer performed the usual checks on the bolts calculating the force on the critical bolt and checked that against the LFD values for a slip-critical bolt in the AASHTO Standard Specs (e.g. a Type F bolt in AISC nomenclature). However, when he checked the "75%" criteria in accordance with (I think it is) Article 10.18.2 he divided that by the capacity of a bolt bearing against material (e.g. a Type N bolt in AISC nomenclature). I told him he should use the Type F bolt limit for all checks regarding bolted field splices. He showed my an example in an AASHTO commentary that used the Type N values for the "75%" strength limit check and said this was what he was using. Anybody want to weigh in on this? I have always used the Type F limits for bolt performance because the code the splices must be designed as slip critical; therefore, the Type N (or Type X) limits have no meaning in this problem; you have to meet the Type F by my understanding. Thanks. - Dinosaur