Modal properties variation and collapse assessment of masonry arch bridges under scour action

Abstract

This paper investigates the problem of flood-induced scour on masonry arch bridges through the analysis of a real case study, Rubbianello Bridge. This is a multi-span masonry arch bridge located in Central Italy, which suffered the collapse of two of the seven spans due to foundation scour during a severe flood in December 2013. The study has a twofold aim: to evaluate with a numerical model the level of scour which led to the bridge failure in 2013 and the corresponding collapse mechanism, and to assess the sensitivity of the bridge's modal properties (vibration frequencies and mode shapes) to different levels of scour. An accurate nonlinear three-dimensional model of the bridge is developed, whose elastic properties are calibrated to match the results of dynamic identification tests performed via Operational Modal Analysis (OMA) on the remaining portion of the bridge. A numerical simulation of the effects of the scour hole progression is also performed on the full bridge, according to recently proposed techniques. The study results provide useful insights on both the cause of collapse of the bridge and the suitability of OMA for bridge scour monitoring.

The Science behind Scour at Bridge Foundations: A Review

“…Figure 1 shows notable examples of bridges that collapsed due to scour in two different countries that are severely affected by floods every year, Italy and the U.K. Among the different types of bridges, masonry arch bridges are the most vulnerable because they are often built on shallow foundations and have a rigid behavior that is sensitive to settlements [22]. The collapse of these bridges caused not only significant direct and indirect economic losses, but also losses of cultural heritage.…”

Electromagnetic Sensors for Underwater Scour Monitoring

“…(1) Pulse or radar devices [16][17][18] High Medium (2) Single-use or float-out devices [19] Low Medium (3) Fiber-Bragg grating systems [20,21] Low Low (4) Sounding or driven rod systems [19,22,23] Medium Medium (5) Sound wave devices [24][25][26] High High (6) Electrical conductivity devices [27] High Medium (7) Dielectric probes [28] High Medium Indirect Scour Measurement Devices (8) Tilt sensors [19,24] Low (9) Accelerometers [26,[29][30][31] Low (10) GPS [32,33] Medium (11) Satellite [34,35] Low…”

Study on the Restoration of a Masonry Arch Viaduct: Numerical Analysis and Lab Tests

“…A numerical model of the masonry arch railway bridge was calibrated using dynamic modal parameters estimated from ambient vibration [34]. The problem of flood-induced scour on masonry arch bridges was also investigated using nonlinear three-dimensional modelling [29,35].…”