According to the following calculation formulas, the program calculates geometric dimensions of the bolt from the specified nominal bolt diameter: Minimum diameter of the nut thread D 1 = d - 1.082531 p … 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. This is the value Shigley used in the 1st edition of Mechanical Engineering Design. where X and Y are chosen dependent on how much conservatism is desired. Again consider the case of 5/8" bolt with a bolt head diameter of 15/16" (1.5 times the bolt diameter) clamping two "plates". With this, the total design shear force for the connection is 1,600 lb (7.12 kN), with each anchor bolt resisting half of the total load. The accuracy of this method is highly dependent on the choice of Q. al. } Green, "Computation of Member Stiffness in Bolted Connections," ASME J. Mech Des., December, 1991, 113, pp. --> This is something that will be looked at in follow-on work to the initial release of this report. There are two locations in this calculation which are different from calculation in ACI 355.3R-11 Example 10. These include Soderberg. Figure 1 contains a cross section of a typical through-bolted joint. To do this, a conservative estimate of the maximum and minimum preloads must be made, so that no factors of safety are required for these preloads. This is overly conservative and in general the NASA values should be sufficient. The down side of this method is that the accuracy is highly dependent on the choice of Q (or the area). Hardware Supplier Manufacturer Because the required factors of safety have already been incorporated, MOS only needs to be positive for the bolt to meet the required factor of safety for combined loading. The original guideline put out by Pulling, et. Figure 2 identifies important geometric parameters for a thread joint. A factor, Q, is defined as the ratio between the actual bolt diameter and the idealized cylindrical stress field, By considering the layer as a one dimensional spring, the stiffness of the ith layer can be computed as, The area of the ith layer can be computed, assuming the inner diameter is qidb (where qi ≥ 1 and is used to allow for clearance between the clamped material and the bolt) and the outer diameter is Qdb, as, The addition of qi is a logical extension to account for clearance holes that were included in the work of Pulling, et. They assumed that the same material is loading in bending as was loaded axially. Due to the complexity of this type of analysis, it should only be done by experienced analysts. This section outlines how to account for the thermal loads. Applied tensile or compressive stress in a stress field. 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. Just to remind you, we’ll follow the ASME BPVC Section VIII Division 1 Appendix 2 ((ASME, “Mandatory Appendix 2 Rules for Bolted … If we have N layers of clamped materials, we have 2*N+2 unknowns (N+1 forces and N+1 extensions, the +1 is for the bolt). This is not strictly correct but is accurate enough with all the other assumptions built into the method. Table 4 gives ranges for nut factors for a variety of materials and lubricants. There is not currently a sufficiently general approach to all of these issues so the engineer must use his/her judgment on them. For real loads, this is non-trivial and multiple methods have been recommended. The first stage is based on idealized models to provide an initial estimate useful for design. There is an additional concern with this method because it is probable that the actual load on the bolt due to bending will be higher than what this theory predicts (i.e. The approach is based on beam theory and as such they are assuming the ends (i.e. Example Calculation Calculation Example – Design bolted … } al. The trends of Morrow [9] seem to be more physically intuitive and are backed up by finite element analysis. the two "plates"). Sample Design Calculations. Using it incorrectly can result in very large errors (due to the fact that Q varies dramatically depending on the joint and materials and any errors in it are at best squared, amplifying the error). [13] and is adopted here. In Figure 9 it can be noted that the results look similar for equal thicknesses of the two materials (i.e. BOLTED CONNECTIONS – II Job No: Sheet 1 of 1 Rev Structural Steel Job Title: Eccentrically Loaded Bolt Group Design Project Worked Example – 1 Made by Date 01-10-00 SRSK Checked by VK Date Calculation Sheet Design Example 1: Design a bolted connection between a bracket 8 mm Remarks thick and the flange of an ISHB 400 column using HSFG bolts… The design … Downloads Engineering Forum Engineering Videos As will be shown by comparing the different methods in a later section, the value of Q is variable and depends on the geometry of the joint. Design recommendations are provided for both allowable stress design and load factor design… For the case where the bolt head diameter (or washer diameter) is greater than the joint "diameter" of the material being clamped, the entire area is used so, where DJ is the diameter of the joint. Bolts and screws are so ubiquitous that it’s impossible to fully articulate their importance or applications. Factor used in the computation of thread tear out, Length of engaged threads needed to avoid tear-out in using high tensile strength bolts. Miner's rule for determining failure due to fatigue can be written simply in the form, where ni is the number of cycles at the ith stress amplitude level and Ni is the number of cycles to failure at the ith stress amplitude. 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. It is a linear theory because it is assumed that sum of the ratios of cycles at a given amplitude to the fatigue life at that amplitude can be summed to get the total effect of the variable loading, and it is independent of the order of the loading. Roach, R. A, Working Draft of "Design & Analysis Guidelines for Satellite Fasteners & Flexures", 2007. Several methods for the design and analysis of bolted joint connections are presented. The thermal load that increases the tensile load will be added to the maximum preload when computing the factor of safety of the bolt. Section 2.1 contains two tables, one for variables defined using the standard alphabet and a second table for variables defined using the Greek alphabet. Disclaimer It is preferable to have the bolt break rather than strip out the threads if a joint is going to fail [12]. | Feedback | Advertising BS449: Part 2 Bolt Grade 4.6, Loading Capacities of Ordinary Bolts per. In addition to the yield limit equations for dowel-type connections, application of spacing, end, and edge distance requirements for connections and provisions related to bolt design … // -->, Bolt Threads, Grade, Bolt Strength, Excel Spreadsheet Calculator, Bolt Pattern Group Pullout Excel Spreadsheet Calculator, Engineering Fundamentals of Threaded Fastener Design and Analysis, Calculating Assembly Torque per ISO 68 & ISO 724, Bolt Elongation Equation and Calculator while under Axial Stress, Fastener / Thread Tensile Area of External Thread Formula, Fastener / Threaded Pitch Circle Diameter Formula and Calculation, Fastener / Threaded  Shear Area Formula and Calculation, Minimum Thread Engagement Formula and Calculation ISO, BS EN 20898-2 Proof load values - Coarse thread, Minimum Length of Thread Engagement Formula and Calculations Per FED-STD-H28/2B, Shear Area Internal and External Thread  Formula and Calculation Per FED-STD-H28/2B, ANSI, ISO Thread Designations and References, Strength Grade Designation System of Steel Bolts and Screws, Self Tapping Screw Pull-Out and Torque Calculator, Torque Table Standard Bolt Sizes SAE Grades 1 - 8, Torque Values Stainless Steel Bolt Table Chart, Bolt Preload Tension Equation and Calculator, Torque vs Tension Bolts Table Chart SAE J429 Bolts, Torque Wrench Adapter Reduced Arm Calculation, Torque Wrench Adapter Extended Calculation, Guide to Design Criteria for Bolted and Riveted Joints, Hydraulic & Pneumatic Torque Wrenches Application Review, Fastener Thermal Expansion / Contraction Application and Equation, Press Fit Engineering and Design Equations, Bolt or Pin In Single Shear Equation and Calculator, Bolt or Pin In Double Shear Equation and Calculator, Single-Riveted Lap-Joint Formulas for Stress and Strength Design Equations and Calculator, Double-Riveted Lap-Joint Formulas and Calculator for Stress and Strength Design, Single-Riveted Lap-Joint with Inside Cover Plate Formulas and Calculator for Stress and Strength Design, Double-Riveted Lap-Joint with Inside Cover Plate Formulas and Calculator, Loading Capacities of Ordinary Bolts per. The next comparison that can be made is using two materials for Shigley's method [16] and the extension of Wileman [17] by Musto [10] and then Morrow [9]. The use of 3 frustums introduces some error as discussed previously. The NASA guide states these uncertainties should be used for all small fasteners (defined as those less than 3/4"). … The second case is for very thick clamping areas. Bickford's [4] method is dramatically different than the other 2 and in comparison will produce much lower clamped material stiffness. aluminum in this case), but significant differences when there is a significant fraction of stiff material (i.e. Fig.1: Anchor Bolt design Example Plan View . For the purposes of this version of the document, washers can either be considered part of the bolt or as individual layers of clamped material. It is planned for follow on work to extend the work of Morrow [9] to cases of more than two materials and perhaps to expand the range of geometries that it is applicable to. The classic example would be a pipe with a bending load applied to it. The design bearing strength at the bolt hole is φRn. The method is the easiest to apply and has been 'verified' since it was based on finite element calculations. For the case of a bolted flange of a pipe with the bending applied to the neutral axis of the pipe, the actual load on the bolt will be more like an axial load and less like a bending load. 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. As can be seen, Q is squared (or raised to the 4th power for bending), and therefore any errors in Q are magnified. The NASA method [11] for incorporating thermal loads into the factor of safety calculations will be adopted here. { A follow on to this work will be to extend the Morrow method to more than two materials and verify the results. 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. how much material is being clamped) relative to the bolt diameter. Units are given in terms of length (L), force (F), radians (rad) and temperature (T). The data is taken from the Standard Handbook of Machine Design [15]. Bolt design per the 2015 NDS is not just a matter of selecting a design value from a table. Try this one: This page provides details on the design and analysis of bolted joints. Calculation Example – Design bolted connection of tension plates (EC3) Create a free account and view content that fits your specific interests in structural engineering Learn More. An unconstrained object will expand due to a change in temperature as, where ΔL is the change in length due to thermal effects, αL is the coefficient of thermal expansion, L is the length, and ΔT is the change in temperature. The Machinery's Handbook [12] and the NASA guide [11] give estimates for the accuracy of bolt preload based on application method. Thread Stress Area Calculator and Equation Bolt Threads, Grade, Bolt Strength, Excel Spreadsheet Calculator… a) The design bearing strength is for service load when deformation is a design … In these cases, any analysis should be done using a range of nut factors to bound the results. - You can calculate the shear strength or the tensile strength of a bolt • Simple connection: If the line of action of the force acting on the connection passes through the center of gravity of the connection, … Physically, this parameter could be different for every clamped layer but for the equations presented in this document, it is assumed to be the same value for all layers.