Preventive maintenance for an old steel railway bridge in Japan: Experimental and numerical study

Maintenance of existing steel structures is of great importance in Japan due to the rapid increasing number of aged structures. A strengthening method for old steel railway bridges by integrating the new structural members has been adopted in engineering practice in this context. In this paper, rubber-latex mortar, GFRP plates and rapid hardening concrete were integrated with an old steel railway bridge to increase its rigidity and reduce the stress levels of the old steel bridge. A railway bridge which has been used for around 100 years was strengthened and tested in this study. The static loading tests on the aged steel railway bridge before and after strengthening were performed to confirm the effects of present strengthening method. Based on the experimental observations, a three-dimensional FE model capable of analyzing this kind of strengthened bridges was built. Experimental results of the steel bridge before and after strengthening, including load-deformation response, strain distribution at salient sections along the span, and strain distribution on the GFRP plates as well as the concrete were reported and compared with the numerical results. Both experimental and numerical results indicated that the renovation method could greatly enhance the stiffness and reduce the stress levels of steel members, resulting in service life extension of the old steel railway bridge.