As such, small errors in Q become large errors in the member stiffness. First, there must be 'symmetric' frustums across the entire joint regardless of the number of materials (otherwise static equilibrium would not be met). He also notes that stress concentration factors for cut threads are much higher. Bolt capacity 4. Effective length of engagement between a bolt and a tapped threaded material (as opposed to a nut), Thickness of the less stiff (lower Young's modulus) clamped material, Thickness of the more stiff (higher Young's modulus) clamped material, Ratio of length of less stiff material to total length of the joint (Equation 21), Number of cycles a joint experiences at the i, Ratio of of an assumed cylindrical stress field to the bolt diameter (typically, Effective radius to which the torque is applied (average of, Analyst's estimate of inner radius of the torqued element (often equal to, Analyst's estimate of outer radius of the torqued element (often equal to, Factor relating total shear load on a bolt to the shear strength of that bolt, Factor relating total tensile load on a bolt to the tensile strength of the bolt, Exponents used in the calculation margin of safety calculations for combining axial and shear loads for a bolt. A preloaded joint must meet, as a minimum, the following three basic requirements: Bolt strength is checked at maximum external load and maximum preload, and joint separation is checked at maximum external load and minimum preload. there is no rotation constraint posed by the material beyond that considered loaded). An analytic expression for the nut factor, K [12], can be written as, where P is the screw thread pitch, μt is the coefficient of friction between the threads, μB is the coefficient of friction between the bearing surfaces, DB is the equivalent diameter of the friction torque bearing surfaces and can be computed when the contact area is circular as. A table of nut factors was given in Table 4. 1. Thread helix angle (Figure 2) and the frustum angle for Shigley's method. These fasteners literally hold the world around us together. The actual value of dh that really should be used is the start of the stress frustum and not the diameter of the bolt head and/or washer. The purpose of this report is to document the current state of the art in bolted joint design and analysis and to provide guidance to engineers designing and analyzing bolted connections. a) The design bearing strength is for service load when deformation is a design … A critical component of designing bolted joints is not only determining the number of bolts, the size of them, and the placement of them but also determining the appropriate preload for the bolt and the torque that must be applied to achieve the desired preload. BS449: Part 2 Bolt Grade 12.9, Excel Spreadheet Design Calculator per. Bickford's [4] and Pulling's [13] work is based on this assumption. else A., J. J. Comer and J. L. Handrock. 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 … Shigley states that typically the angle to use should be between 25 and 33 degrees and in general recommends 30 degrees (this is assuming a washer is used). 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. The external axial load applied to separate clamped materials. Guidance is provided for general bolted joint design, computation of preload uncertainty and preload loss, and the calculation of the bolted joint factor of safety.