சி. எஸ். ஐ. ஆர். - கட்டமைப்பு பொறியியல் ஆராய்ச்சி நடுவம்

Full scale field investigations and response measurements were carried out on an open web girder type road cum railway bridge in order to assess the cause for damage to the bridge and to evolve the suitable retrofitting schemes. Based on the measured responses and from the numerical modelling of the damaged and undamaged portals, it was observed that the distress in the gusset and cross girder is mainly due to the load on the flange of the cross girder of the portal which is applied eccentrically. The strain measurements on the cross girder, gusset, bracing and vertical member of the two typical portals shows that the damaged portal experiences more bending strains than the undamaged portal. The excessive stresses are observed to be mainly because of the failure of seating at the intermediate joints and application of eccentric loads. The undulated and damaged road surface is also the cause for the vibration of the bridge during movement of road traffic. To mitigate the damage in the cross girder and the gussets, a suitable modification of the cross girder is suggested. A closed box section is suggested in place of existing I-section to cater for the torsional stresses being developed because of the eccentric loads on the cross girder at intermediate expansion joint.