Fundamentals of Structural Engineering -2/E

The second issue is related to the behavior of the material used to fabricate structural members. Steel and concrete are the most popular materials for structural applications. These materials have a ?nite elastic range, i.e., they behave elastically up to a certain stress level. Beyond this level, their stiffness decreases dramatically and they experience signi?cant deformation that remains when the specimen is unloaded. This deformation is referred to as “inelastic deformation.” The result of this type of member behavior is the fact that the member has a ?nite load carrying capacity. From a structural system perspective, it follows that the structure has a ?nite load capacity. Given the experience with recent structural failures, structural engineers are now being required to estimate the “limit” capacity of their design using inelastic analysis procedures. Computer-based analysis is essential for this task