An Updated Overview of BridgePBEE

Screen Shot 2018-03-13 at 9.33.27 AMBridgePBEE has been recently enhanced by incorporating robust plotting and visualization packages to make this user-interface more versatile and user-friendly. An overview was presented at the 2018 PEER Annual Meeting, Plenary 4 Session, “Performance-Based Engineering: Research”, in the presentation “Towards a Performance Assessment Calculation Tool (PACT) for Bridge Systems,” by UC San Diego Professor Ahmad Elgamal.

BridgePBEE is a graphical user-interface (GUI) for conducting Performance-Based Earthquake Engineering (PBEE) studies for bridge-ground systems (2-span single-column type). The interface combines nonlinear time history analysis (using OpenSees) of bridge systems with an implementation of a PBEE methodology developed by PEER. In the time history analysis, the bridge column is modeled using beam-column elements with a nonlinear Fiber section. Abutment models considering bearing pads and shear keys are also included. Bridge column, deck, abutments, and supporting soil strata are integrated within a unified framework. Systematic evaluation of the global system response is conducted under a wide range of earthquake input shaking scenarios. In BridgePBEE, all stages of the involved analyses including the PBEE assessment are executed in a systematic fashion, allowing the user to conveniently conduct extensive parametric investigations. The analysis options available in the interface include: i) Pushover analysis; ii) Mode shape analysis; iii) Single and multiple 3D base input acceleration analysis; and iv) Full PBEE analysis.

The interface is unique as it enables complete PBEE studies in a single GUI-driven package. The framework includes several intermediate probabilistic models that allow the user to generate probabilistic estimates of repair cost and repair time (consequences or decision variables) directly. These results are obtained seamlessly in the interface alongside more traditional outputs such as displacements, strains, etc. The intermediate probabilistic models are: i) Hazard model that uses earthquake ground motion data to determine an intensity measure (IM); ii) Demand model that uses response from dynamic analysis to determine an engineering demand parameter (EDP); iii) Damage model that connects the EDP to a damage measure (DM) or discrete set of damage states (DSs) and then to repair quantities (Qs) needed to return bridge components to original functionality; and iv) Loss model that links Qs to consequences that are termed as the decision variables (DV). Repair cost and repair time can be thought of as two possible decision variable (DV) outcomes characterized probabilistically by the framework.

As such, the decision variables that can be generated as output are the repair cost ratio (RCR), or the ratio of repair cost to replacement cost, and the repair time (RT) or repair effort, measured in terms of crew working days (CWD). These outcomes are presented graphically as loss models conditioned on earthquake intensity. In addition, site-specific ground motion hazard can be specified, and the user-interface will then also generate loss hazard curves (mean annual frequencies of exceeding different loss levels). The loss hazard curves are presented graphically as mean annual frequencies or return periods.

An important feature of the interface is that the PBEE analysis can be executed sequentially: i) ground motion selection, ii) time history analysis, iii) loss (repair cost and time) modeling, and iv) calculation of hazard curves. Once the time history results are computed, the user can display the results against any IM and perform what-if scenarios by changing any parameter of the intermediate damage, loss, and hazard models. The PBEE portions of the analysis do not require recomputing the time history results unless the model has been changed or a new selection of ground motions has been made.

Go to to access this valuable tool and user manual.