Span Calc vs WeldCalcs

The American Wood Council (AWC) Span Calculator for Wood Joists and Rafters (Span Calc) performs calculations for all species and grades of commercially available softwood and hardwood lumber as found in the 2021 National Design Specification® (NDS®) for Wood Construction. Joists and rafter spans for common loading conditions can be determined. A span options calculator allows selection of multiple species and grades for comparison purposes. Supported by the Softwood Lumber Board. Maximum horizontal spans for joists and rafters are calculated based on the following assumptions and conditions: · Joists and rafters are oriented to support vertical loads applied to the narrow (1.5 in. thick) face of the member, resulting in strong-axis bending. · At least three joists or rafters are installed parallel to one another and spaced not more than 24 inches on-center, with properly designed sheathing attached on the top (compression) edge of each joist or rafter. · Joists and rafters are single-span with adequate structural support at each end. The Span Calculator does not address cantilevered joists and rafters, multiple-span joists and rafters, or spliced joists and rafters. · For joists and rafters, most building codes specify a minimum bearing length of 1.5 inches on wood or metal and not less than 3 inches on masonry or concrete. These minimum bearing lengths are to be used in the absence of calculated bearing lengths. Consult the local building code for specific requirements. · Joists and rafters carry only combinations of dead load plus live load (D + L), dead load plus snow load (D + S), or dead load plus roof live load (D + Lr). The Span Calculator does not address wind load or seismic load. · Buildings in regions with ground snow loads greater than 70 psf should not use the prescriptive provisions of the governing building code without approval of the authority having jurisdiction. Buildings in these high snow zones should be designed in accordance with accepted engineering practice. While every effort has been made to insure the accuracy of the information presented, and special effort has been made to assure that the information reflects the state-of-the-art, neither the American Wood Council nor its members assume any responsibility for any particular design prepared from this Span Calculator application. Those using this Span Calculator assume all liability from its use.

Useful for the preliminary sizing of fillet welds, WeldCalcs is an engineering calculator app that computes the section properties for typical welding patterns used in steel construction. After selecting a Weld Group, the user enters the dimensions for the depth and width, along with any combination of applied forces and moments. The section properties for the Weld Group, including the area, section moduli and polar moment of inertia, are instantly calculated. The app also determines the maximum resisting resultant force and the initial fillet weld size. The calculations performed by the WeldCalcs app are based on the Elastic Method. This approach treats the weld as a line or a group of lines. This allows the weld group section properties to be determined without knowing the size of the weld. The section properties and the applied loads are used in structural engineering formulas to determine the maximum resisting resultant force along the weld. This resultant force is expressed in terms of force per unit length. Since the weld is evaluated based on a force per unit length, in lieu of stresses, combining the effects from different load types (shear, axial, moment, torsion) is easily accomplished. The applied moments and torsions are resolved into vertical, horizontal and axial components and then vectorially combined with the directly applied shears and axial forces. All of the applied loads are assumed to act through the center of gravity of the weld. Therefore, each segment of the weld resists an equal share of the direct shear and axial forces and a proportional share of the bending moments and torsions relative to the weld segment's distance to the neutral axis of the weld group. The fillet weld size is determined by dividing the maximum resisting resultant force by the available strength of the weld. For practicality, both weld dimensions 'd' and 'b' are limited to a minimum value of 0.25 inches and a maximum value of 100 inches. Dimensions 'tw' and 'tf' are limited to a minimum value of 0.125 inches and a maximum value of 10 inches. The applied forces are limited to a range of -99,999 to +99,999 kips. The applied moments are limited to a range of -99,999 to +99,999 kip-inches. The equations for the section properties and resultant forces used by the app are available for reference and manual verification by the user. The general equations for the resisting forces in each quadrant are based on the applied forces and moments all acting in the positive direction.