Civil infrastructure in the U.S. is aging and has been identified as an area in critical need. Many bridges of great importance are approaching the end of their lifespan. It is necessary to determine and monitor their structural health in order to mitigate risks, prevent disasters, and plan maintenance activities in an optimized manner. The need for reliable, robust, and low-cost Structural Health Monitoring (SHM) is thus rapidly increasing. In spite of its importance, however, SHM is rarely utilized on real structures. The main reason for this is the cost and limited reliability achievable by current monitoring technologies. The sensors currently available must be sparsely spaced and either provide severely insufficient spatial-resolution for early damage detection or rely on complex algorithms that degrade specificity against environmental and variable-load conditions. The objectives of this research are two-fold: to investigate sensing-system principles that provide affordable monitoring through a dense and expansive array of sensors enabled by distributed fiber optic technology and technology called large-area electronics; and to experimentally study how the high-resolution sensing offered by such systems can overcome the robustness and reliability limitations affecting current SHM technologies. The main concepts are presented in this paper along with both reduced- and large-scale test results, which demonstrate that the proposed technologies and direct sensing approach are beneficial for reliable damage detection and localization of damage over large areas of a structure.