Assessment of Seismic Integrity of Multi-Span Curved Bridges in Mid-America

The study presents a detailed seismic performance assessment of a complex office-designed bridge using state-of-the-art assessment tools and metrics. The impact of design assumptions on the capacity estimates and dynamic characteristics of a multi-span curved bridge are investigated. A single nine-span bridge is studied whilst the level of attention to detail is significantly higher than can be achieved in a mass parametric study of a population of bridges. The objective is achieved by in-depth investigation of the bridge representing the ???as-designed??? (including features assumed in the design process) and that representing the ???as-built??? (actual expected characteristics) structure. Three-dimensional detailed dynamic response simulations of the investigated bridge including soil-structure interaction effects are undertaken. The behavior of the ???as-designed??? bridge is investigated on two different analytical platforms for elastic and inelastic analysis. A third idealization is adopted to investigate the ???as-built??? behavior by realistically modeling bridge bearings, structural gaps and materials. A comprehensive list of local and global, action and deformation, performance indicators are selected to monitor the response to earthquake action, including bearing slippage and segment collision. The adopted methodology and results of elastic and inelastic analyses are discussed. The comparative study has indicated that the lateral capacity and dynamic characteristics of the as-designed bridge are significantly different than the as-built behavior. The potential of pushover analysis in identifying structural deficiencies, estimation of capacities and providing insight into the pertinent limit state criteria are demonstrated. The conclusions from this study are important for designers and assessors of the seismic response of complex bridges since it highlights potentially non-conservative assumptions that are frequently used in the design office.NSF Grant EEC-9701785published or submitted for publicatio