ABSTRACT
Around 20,000 masonry arch bridges are currently operational with the Indian Railways of which 16,000 bridges are at least 100 years old. There is a constant need to assess and if necessary, retrofit and upgrade these bridges to meet the current demands of new seismic performance requirements, increased axle speeds and loads, traffic volume, etc. The geometric dependence of failure mechanisms has made limit analysis an obvious choice for the assessment of masonry arch bridges. In this context, a simple, yet robust, first-level quantitative assessment procedure which can be applied to a large stock of masonry arch bridges with minimum input parameters is proposed. The collapse factor is calculated based on equilibrium of internal and external work, resulting from the virtual displacement of the rigid block. For a given single span masonry arch bridge under seismic action, the governing collapse factor is identified as the minimum of all possible failure mechanisms.
