Which wood design factor accounts for the increased strength of wood under short loading periods?

The factor that accounts for the increased strength of wood under short loading periods is the Cd, which stands for the duration of load factor. This factor acknowledges that wood can actually withstand greater stress levels over short periods of time compared to longer loading durations.

This is primarily due to the nature of wood as a material, where the time dependency of its strength is influenced by how wood fibers respond to stress. For short-term loads, the fibers in the wood are better able to handle higher stresses before failure occurs. Designers and engineers utilize this factor to ensure that structural elements can safely carry loads that are applied for limited durations, such as during construction loads, impact loads, or transient loads from gusts.

In contrast, other factors such as Cm (moisture content factor), Cl (load duration factor), and Ct (temperature factor) serve different purposes in the design process and do not specifically address the increase in strength that wood exhibits under short loading conditions.