Moment Resistance Calculation

Using O86 6.5.3.1 for sawn lumber, 7.5.6.5 for glulam, and 15.3.3.1 for SCL SIzer determines factored bending moment resistance with equations of the form

M_r = f F_bSK_zbK_L

• f = 0.9.
• F_b is the specified bending strength f_b multiplied by wet service, treatment, system, and load duration factors.
• S is the section modulus
• K_zb is a size factor defined differently for each material. Refer to Glulam Bending Moment Design and SCL Size Factors for more details.
• K_L is the lateral stability factor.Refer to Lateral Support and Beam Stability Factor KL and its subtopics for more details.

For glulam, K_zb and K_L are not applied simultaneously, the lesser value is used. Refer to Glulam Bending Moment Design for more details.

CLT moment resistance is calculated using and 8.4.3.2, and 15.2.3.1 is used for I-joists for which M_r comes directly from the database for each section.