Forces that cause materials to change shape or size belong to which category?

Load forces are the correct category for forces that cause materials to change shape or size. In the context of building construction, load forces refer to the various types of loads applied to a structure, including dead loads (permanent static weights such as the weight of the structure itself) and live loads (temporary or dynamic forces such as occupants, furniture, or environmental factors like snow or wind).

These forces enforce stresses and strains on materials, leading to potential deformation or failure if the materials are pushed beyond their limits. Understanding load forces is essential for engineers and architects during the design process to ensure that structures can safely support applied loads without significant alteration in their shape or structural integrity.

The other categories mentioned refer to different aspects of force application. External forces encompass all forces acting on a structure from outside sources but do not specifically imply the material's response. Internal forces relate to the internal stresses induced by external loads but do not necessarily focus on the category of forces causing shape changes. Impact forces specifically denote sudden forces that could lead to immediate effects, but they do not represent the general category of forces like load forces do.