In the world of construction and infrastructure, the devil is often in the details—and nowhere is this more true than in the design and implementation of prestressed concrete (PC) girders. A recent study published in the Archives of Civil Engineering (Archiwum Budowy i Inżynierii Lądowej), led by Guangqing Xiao of Guangzhou Guangjian Construction Engineering Testing Center Co., Ltd, has shed new light on the effective anchorage stress of prestressed tendons in PC girders, challenging the one-size-fits-all approach currently prescribed by design codes.
The study, which investigates the impact of tendon span length and tensioning sequences on effective anchorage stress, has significant implications for the construction industry, particularly in the energy sector where large-scale infrastructure projects are common. “Current design codes prescribe a uniform anchorage stress for all PC girders, regardless of their span length,” Xiao explains. “Our research demonstrates that this approach is not accurate and can lead to inefficiencies and unnecessary costs.”
The research team conducted a comprehensive theoretical analysis, accounting for various stress losses such as conduit friction, anchor deformation, and concrete compression. They focused on small-box girders with span lengths of 20 m, 25 m, and 30 m, as well as 40 m T-shaped girders. Their findings revealed that the effective anchorage stress varies depending on the girder’s length and the sequence in which the tendons are tensioned.
This is a significant departure from the current industry standard, which prescribes a uniform effective anchorage stress of 1280 MPa. Based on their findings, Xiao and his team propose refined effective anchorage stresses tailored to specific girder lengths: 1237 MPa for 20 m girders, 1244 MPa for 25 m girders, 1251 MPa for 30 m girders, and 1251 MPa for 40 m T-shaped girders.
The adoption of these refined values could have a substantial impact on the construction industry. According to the study, using the new evaluation method for effective anchorage stress can improve the prestressed quality passing rate by up to 10.9%. This means fewer instances of unnecessary supplementary tensioning or excessive tensioning during on-site construction, leading to cost savings and improved project efficiency.
The findings also have implications for the energy sector, where large-scale infrastructure projects often involve the use of PC girders. By adopting a more nuanced approach to effective anchorage stress, energy companies can ensure the longevity and safety of their infrastructure, while also reducing construction costs.
As the construction industry continues to evolve, research like Xiao’s is crucial in driving innovation and improving industry standards. “Our goal is to provide a more accurate and efficient method for assessing effective anchorage stress,” Xiao says. “This will not only benefit the construction industry but also contribute to the overall safety and sustainability of our infrastructure.”
The study, titled “Effective anchorage stress of prestressed tendons in PC girders under varying tensioning sequences,” was published in the Archives of Civil Engineering, a peer-reviewed journal that focuses on civil engineering and related fields. As the industry continues to grapple with the challenges of large-scale infrastructure projects, research like this is a beacon of progress, guiding the way towards a more efficient and sustainable future.