Kabe-bairitsu (壁倍率) – in Japanese wooden construction (木造建築), kabe-bairitsu is the numerical shear strength value or scale factor of a structural wall. If a shear wall that is 910 millimeters wide by 2730 millimeters tall (center to center) with a single wooden diagonal brace 15 by 90 millimeters in cross-section equals 1, then kabe-bairitsu is the value x that is equal to the factor by which the wall in question is stronger than 1.

x = ab where a is the shear strength of a given wall based on the designation of b, the example wall, as 1.

Scale Factor for Structural Walls

The image above illustrates the kabe-bairitsu (structural wall scale factor) of various kinds of shear walls. Note that the diagonal bracing must be fastened with the certified hardware and fasteners in order for these values to hold. See How to build earthquake resistant homes for more information on hardware, fasteners, and how to use the kabe-bairitsu in real-world equations.

As this is an empirically derived value, there are many factors that can influence the actual or overall value of a shear wall or structure. For example, nail type and pitch, plywood type and thickness, additional hardware etc. Structural plywood must also overlap onto the structural beam above and foundation below to be effective.

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