Eco-Structure Design

Following the successful completion of Phase 1 of the Alaska Prestressed Concrete Decked Girder (AASHTO-j type) Design Optimization Project, led by Dr. Galib, the research has advanced into Phase 2 at North Carolina State University, Raleigh, USA, with Khan joining this phase to lead the refinement and experimental validation efforts. Phase 2 focuses on enhancing the previously optimized girder designs by incorporating practical constructability considerations, industry constraints, and code-compliant detailing, alongside comprehensive large-scale laboratory testing to evaluate structural performance and feasibility under realistic loading conditions. The successful validation of these next-generation prestressed girders will enable the adoption of longer-span alternatives to conventional Alaska girders, reducing material usage, minimizing substructure requirements, and lowering lifecycle environmental impacts, thereby supporting more efficient, resilient, and sustainable bridge construction practices. 

In the country’s first formal and systematic initiative in girder design optimization, Syed-Uz-Zaman and Razesh are undertaking the development of optimized designs for traditional prestressed concrete I-girders with cast-in-place decks (AASHTO-K type) for the Local Government Engineering Department, Bangladesh (LGED) as part of their MSc research at BUET. The study seeks to enhance structural efficiency, cost effectiveness, and material utilization while ensuring full compliance with applicable design codes and practical constructability requirements. By introducing optimization-based design methodologies into conventional girder systems widely used by LGED, this research has the potential to influence standard design practices and promote more economical and sustainable bridge construction at the national level. The work is carried out under the formal supervision of Dr. Raquib Ahsan, with additional technical oversight provided by Dr. Galib. 

Asif, Ruhul and Tamjid are investigating (Under the supervision of Dr. Galib) the overall advantages of optimized long-span girders for the Tanana River Bridge near Tok, Alaska. While extending girder spans reduces the number of required piers and foundations, the increase in superstructure material is not entirely balanced by the reduction in substructure materials. In fact, the cost of superstructure materials can exceed that of shorter spans by more than 1.5 times, with only partial compensation through savings in the substructure. Nevertheless, the secondary benefits of longer spans are significant: fewer piers reduce disruption to natural water flow, mitigate scouring, and promote healthier aquatic ecosystems and riparian vegetation. Additionally, the reduced number of piers and foundations leads to shorter construction durations and lower long-term maintenance costs. This study aims to quantify these comprehensive benefits to support the case for adopting optimized longer girder spans for the Tanana River Bridge and for any bridge in general.