Construction Technology for Ultra-Long Composite Girders of Shenzhen Museum Using Bonded Post-Tensioning Prestressing Approach

Long-span prestressed structures present distinct challenges during tensioning. Their considerable length inherently induces significant tendon friction, resulting in substantial prestress loss. Additionally, prestressing operations within buildings will induce initial stresses that affect adjacent structural members. However, research on the design and construction of ultra-long-span prestressed systems with composite materials in building structures remains limited. To investigate prestress effects in long-span building structures, this study examines prestress loss and tension timing for the 94.34 m arch tie girder in Shenzhen Museum. This project marks the first application of the bonded post-tensioning method to an ultra-long composite structural member. The analysis of the prestress loss is conducted by considering the friction, relaxation of steel tendon, creep, and shrinkage. An innovative finite element method, integrating creep and shrinkage effects for composite members, is developed in ANSYS. Four tensioning schemes are compared using nonlinear staged-construction simulation in NIDA software. The results demonstrate that the presented analytical method can effectively quantify the prestress loss. Early-stage prestressing effects can be minimized by optimizing the force transmission paths through construction joints. These findings provide practical and theoretical guidance for designing and constructing similar long-span structures.