Statically Determinate Truss Structures

Overview

We begin this chapter by reviewing the historical development of truss structures. Trusses have played a key role in the expansion of the highway and railroad systems during the past two centuries. From a mechanics perspective, they are ideal structures for introducing the concepts of equilibrium and displacement. We deal first with the issues of stability and static determinacy, and then move on to describe manual and computer-based techniques for determining the internal forces generated by external loads. A computational scheme for determining the displacements of truss structures is presented next. Given a structure, one needs information concerning how the internal forces vary as the external live load is repositioned on the structure for the design phase. This type of information is provided by an influence line. We introduce influence lines in the last section of this chapter and illustrate how they are constructed for typical trusses. This book focuses on linear elastic structural analysis. Although nonlinear structural analysis is playing an increasingly more important rule in structural design, we believe an understanding of linear analysis is essential before discussing the topic of nonlinear analysis.