Driven by the necessity to meet changing public expectations in the wake of natural disasters, such as earthquakes, the structural engineering community has been moving towards rational, risk-informed, and transparent approaches to structural design, amidst which probabilistic performance-based seismic design (PBSD) has emerged as the most scientific and promising one. The main objective of this research is to formulate a simplified yet rigorous framework for risk-targeted PBSD of Ordinary Standard Bridges (OSBs), which, despite being simple bridges, constitute an integral part of lifeline infrastructure systems, especially in earthquake-prone regions such as California. A seismic performance assessment methodology integrating site-specific seismic hazard analysis, structural demand analysis, and damage analysis in a comprehensive and consistent probabilistic framework is computationally implemented as a modular tool unifying several state-of-the-art advancements related to the field. This tool is used for a parametric probabilistic performance assessment of four different testbed OSBs over a primary design parameter space to investigate the effects of varying key structural design parameters on targeted structural performance measures. Erratic performance levels exhibited by these real-world traditionally designed bridges, compared to expert-opinion-based target performance levels, expose the inconsistency and opacity of current (prescriptive) design principles that do not explicitly state, analyze, and design for risk-targeted performance objectives but implicitly expect them to be satisfied. A comprehensive risk-targeted simplified yet rigorous PBSD method is distilled out and proposed, and its efficacy is validated using four real-world bridges as cases in point. The framework is then enhanced by the inclusion and consistent propagation of pertinent sources of uncertainty (typically ignored in practice) to obtain a more complete picture of seismic performance, thereby leading to a more comprehensive, transparent, and reliable design of OSBs, facilitating effective and risk-informed decision-making in the face of uncertainty. It is believed that the adoption of the proposed PBSD methodology, although non-traditional in its format, will be highly beneficial in the medium to long term. This initial venture will also prove crucial in supporting and fostering future research work and innovative technological developments in bridge infrastructure engineering.