Materials for Structural Models

Advantages and disadvantages of commonly used model materials are discussed. Plastics are used for indirect models or direct models in the elastic range. They follow Hooke’s Law for the range of strains usually used and have low moduli of elasticity, so measurable strains and deflections can be obtained with small loads. They can be easily formed, machined, and assembled, but their mechanical properties are sensitive to environment and methods of test. For modeling reinforced concrete structures up to ultimate load, cementitious materials with similar stress-strain curves up to failure as the prototype must be used. The properties of frequently used cementitious materials, particularly micro-concrete, are discussed. Model reinforcement is limited to steel or phosphor bronze because of the need of fairly well pronounced yield points. Threaded rod can be used to assure sufficient bond for gypsum mortar. Metallic models can be made of steel, aluminum and copper alloys. Miscellaneous materials such as cement asbestos, cardboard and wood are discussed.