The Seismic Retrofitting of Reinforced Concrete Bridges: Global Methods and Local Applications in Duhok City, Iraq

Abstract

Bridges built before the introduction of the modern seismic design codes are very prone to damage caused by earthquakes, especially in developing regions that do not have systematic retrofit programs. In Duhok City, Iraq, the rising seismic activity, in addition to the deterioration of reinforced concrete (RC) bridges, poses a high threat to the resilience of transportation and the safety of the population. The current research is focusing on reviewing the world methods of seismic retrofitting of RC bridge structures and on their suitability for the local area of Duhok. To fulfil these goals, a literature study of worldwide seismic retrofitting techniques has been performed, which includes steel jacketing, composite material wrapping (CFRP), reinforced concrete jacketing, foundation retrofitting, base isolation, smart materials, and viscous dampers. The methods were relatively evaluated in terms of performance in the form of cost, feasibility of application, strength improvement, and ductility improvement. Simultaneously, the field research processes were conducted using qualitative research methods, as on-site visits and consultations with local infrastructure officials were conducted to examine current practice in the retrofitting process and retrofit design in Duhok. The findings shown reveal that, although the global techniques that have been verified to strengthen, enhance the ductility, and the seismic performance of materials used in the constituents of RC bridges, there are no systematic seismic retrofit programs presently implemented in Duhok. There are no elaborate performance-based examinations of the seismic factor, but simply a simplified approach to the design practices. Comparative analysis indicates that the steel jacketing and CFRP wrapping offer the best balance between performance and feasibility of normal bridge elements in the area, whereas other advanced systems, including base isolation and shape memory alloys, are more appropriate to critical infrastructure that must be functional immediately after the earthquakes occur. The results show that there is a critical lack of connection between global developments in seismic retrofitting and local application. The creation of a national retrofit system and the incorporation of methodologies focusing on performance-based assessment will be necessary steps toward enhancing seismic resilience in Duhok and other areas.