Present day status and numerical modelling of heritage masonry bridges of Kalka-Shimla Mountain Railways

Abstract

This study is conducted on two masonry arch skew bridges located on UNESCO recognised Kalka-Shimla Mountain Railways, India, built in the year 1905 with stone masonry located in seismic zone IV as per Indian Standard Code 1893 (2016). Hence, the present day assessment and seismic performance evaluation of the bridges is necessary for conservation. In this study, field measurement of the bridges is conducted using ambient vibration testing (AVT) and operational modal analysis (OMA) with sensitive accelerometers and data acquisition system. Further, modal parameters have been extracted using frequency spatial domain decomposition (FSDD) technique from recorded data. Furthermore, the measured response of the bridges is compared with the developed initial numerical model to estimate the present day status of the bridges in terms of material degradation. A reliable model is then developed adopting modal updation trial and error procedures. At last, the study is concluded towards understanding status of material degradation and preparation of reliable numerical models of the heritage bridge structures