We present principles and techniques for design of Web-enabled data aggregation, storage, and visualization software for structural health monitoring of civil infrastructure: the process of collecting and analyzing sensor data related to the condition or behavior of constructed facilities (e.g., bridges, dams, tunnels) to promote safe and efficient service at a reasonable cost. Due to widely variable user requirements and the vast range of data types and display methods required, good human-computer interfaces for engineering applications are still difficult to design and implement, and continue to be constructed in more-or-less ad hoc manners. We approach human-computer interaction in the civil engineering domain through common HCI methods, such as user interviews, use case design and analysis, representation in UML, and so on. However, this paper is focused on two special techniques that are not commonly found in HCI development: (1) a rigorous analysis of the nature of the data and how it will be used, and (2) a general method for sending data into functions for display on the user interface. The addition of two techniques like the above adds new tools to the engineering HCI toolkit and increases HCI designers' ability to meet the needs of engineers who examine large volumes of engineering data.