*What is meant by “government-specified construction materials”?

These materials are defined as wooden materials, steel, concrete, and other construction materials, stipulated by the Minister of Land, Infrastructure, Transport and Tourism under the Building Standards Act, Article 37 (Quality of Construction Materials), to be used for the foundation, principal structural parts, and other parts of a building, which are deemed important in terms of safety, fire prevention, or hygiene as specified by Cabinet Order.
*What is meant by “principal structural parts”?
These are parts defined under the Building Standards Act, Article 2, Section 5, including: walls, pillars, flooring, crossbeams, roofing, or stairs. The following parts are not considered important in terms of a building’s structure and are therefore excluded: partitions, columns, corner posts, raised floors, floors on the bottom, revolving stage floors, binding beams, eaves, localized small stairs, outdoor stairs, or similar.

Aluminum alloy materials have been added to the regulations defining the specifications and technical standards pertaining to construction material used in the foundation, principal structural parts, etc. of a building, as well as the quality level that must be met for this construction material. In addition, the standards applying to the quality of aluminum alloy materials were also defined (JIS H4000, 4040, 4100, 4140, 5202, and Z3263).
In brief, aluminum alloy materials were named government-specified construction materials that can be used in pillars, beams, floor slabs, roof shingles, and other parts important to structural durability. These are quality specifics for materials incorporating aluminum materials.

Standards pertaining to aluminum alloy have been established on the allowable stress and strength of structural materials used, as well as on their benchmark strength, based on which the calculation of the allowable stress and strength is implemented. These are critical indices for considering and ascertaining safety in structural calculations. These standards have allowed for structural calculations due to the establishment of specifications on basic indices such as allowable stress and material strength including compression, tension, bending, and shearing, as well as specialized allowable stress and specialized material strength pertaining to buckling, etc.

General specifications were stipulated where structural calculations cannot be made on structural methodology for aluminum structures.
In other words, technical standards have been established to govern the safety of structural methodology for aluminum structures, allowing for confirmation of structural calculation and requirements. Applicable areas include regulations on size (area), joint parts, slenderness ratio of compression members, leg format, measures against horizontal force,