Musto, J. C. and N. R. Konkle, "Computation of Member Stiffness in the Design of Bolted Joints", ASME J. Mech. A table of nut factors was given in Table 4. The relative amount of each material will be varied from 10% to 90% of the total joint thickness. Oberg, E., F. D. Jones, L. H. Holbrook, and H. H. Ryffel, Machinery's Handbook, 27. Based on the pros and cons of each method, it is recommended that the empirical method of Morrow [9] be used as the preferred method when it is applicable. The external axial load applied to separate clamped materials. These tools definitely help to drastically reduce the design time. To determine if the internal threads will strip out before the bolt break, first compute the factor J as, where Sy,ET is the tensile strength of the external thread material and Su,IT is the tensile strength of the internal material and the shear areas of the external and internal threads are computed as. Any geometric or material effects that significantly violate this assumption make the approaches in this section invalid. This is not strictly correct but is accurate enough with all the other assumptions built into the method. It is planned to update this document in the future, and this is one area that needs additional work. As is typical with bolted connections subjected to shear, the load is … … For this case, the shape of the actual stress distribution looks more like a barrel and the shape assumed by Shigley is inappropriate. Due to flexibility in the bolt or washer, the correct value of dh will be less than the bolt head (or washer) diameter and the degree to which it is less depends on the relative stiffness of the materials involved. This implies a Q factor of. The load can be obtained from either analytic models or finite element analyses. They assumed that the same material is loading in bending as was loaded axially. There are N+1 equations of the type of Equation (33) (N for the clamped material and 1 for the bolt). Safety factors need only be applied to external loads. design and detailing are of primary importance for the economy of the structure. This can range from a relatively simple axisymmetric linear elastic finite element model to a fully nonlinear three dimensional finite element model incorporating geometric nonlinearities and frictional contact. A change in temperature can cause an increase or a decrease in the preload of the bolt. It is not recommended to use these equations. Design of bolted beam-column connections Bolt capacity of force resistance needs to be calculated in most of the connections except some seated connections as shown in The general procedure of bolted beam-column connection design is: Fig.2.4 and Fig.2.5 (bolts … All of the analytic or empirical approaches presented in this chapter make assumptions and are quite good in many cases but none applies in every case. The Soderberg method is very conservative and seldom used. NASA [11] chose X = 2 and Y = 3 and Bickford [5] states these are the accepted aerospace values. They concluded that there is not significant degradation of the joint until the edge or corner effect is within 1.5 bolt diameters of the hole. To get a quantitative comparison of the various analytic method relative to one another, consider the case of 5/8" bolt with a bolt head diameter of 15/16" (1.5 times the bolt diameter) clamping two "plates" of the same material. [13], went on to define a bending stiffness for the clamped material using the same methodology. There are a number of subtleties that must be noted based on the assumptions in this method. It, and extensions to it, will be presented in the next section. BS449: Part 2 Bolt Grade 12.9, Excel Spreadheet Design Calculator per. Durbin, Morrow, and Petti [9] analyzed Musto's results and concluded a general purpose equation across materials and geometries could be written. Due to the complexity of this type of analysis, it should only be done by experienced analysts.