Seismic Evaluation & Retrofit of Existing Structures

Each structure is evaluated as a unique system shaped by its original design philosophy, construction practices, usage history, and modifications over time. The evaluation process begins with on-site investigations, including detailed site visits to understand the as-built structural configuration, load paths, foundation system, and observable signs of distress or deterioration.

Where original design information is incomplete or unreliable, the existing structural system is identified through field observations, measurements, and review of available documentation. Material properties are established based on available records, in-situ testing, and laboratory data, including mechanical properties of materials, and reinforcement detailing. These findings form the basis for realistic analytical modeling.

When the behavior of a structure cannot be reliably inferred from drawings and tests alone, we complement analytical modeling with measurements obtained directly from the structure. Using structural health monitoring tools, we observe how the structure responds to ambient and operational conditions, and use this information to verify and refine our analytical models. This step helps ensure that the models used in evaluation reflect the actual behavior of the structure, rather than idealized assumptions.

Following this groundwork, analytical models are developed at a level of detail appropriate to the problem at hand. Evaluations are carried out using performance-based seismic engineering principles, allowing expected deformation demands, damage states, and failure mechanisms to be explicitly examined under different earthquake scenarios. Linear and nonlinear analysis procedures are employed as appropriate, including nonlinear static and dynamic methods when required to capture critical response characteristics.

Retrofit strategies are developed only after the governing deficiencies and response mechanisms are clearly identified. Rather than defaulting to strengthening measures, we examine alternative approaches—such as system reconfiguration, redistribution of demands, or targeted local interventions—to achieve the desired performance objectives in a rational and efficient manner.