Flexural Behavior and Optimization of Full-Scale Prestressed Concrete Double-Tee Beams

This study presents an integrated investigation into the flexural behavior of full-scale prestressed concrete double-tee beams (DTBs) to address gaps in size-effect understanding, simulation fidelity, and design optimization. Full-scale bending tests on 18-m and 24-m topped/untopped DTBs revealed notable size-dependent phenomena: crack spacing exceeded code predictions by 15%–20%, and ductility mechanisms differed fundamentally from scaled models. An ABAQUS finite element model with the concrete damage plasticity (CDP) framework and calibrated bond-slip behavior achieved high fidelity, with < 4.5% error in load-deflection predictions while capturing prestress evolution and crack propagation. Comparative analysis of six design codes (GB50010, ACI 318, Model Code 2010, etc.) showed systematic inaccuracies—ACI 318 underestimated deep-section (980 mm) flexural strength by up to 33.3%, while Model Code 2010 (with explicit size-effect factors) aligned within ±26% of experimental data. Topology optimization reconfigured solid ribs into ultra-high-performance concrete (UHPC) trusses, reducing mass by 38% while increasing ultimate capacity by 12.1% and ductility by 9.2%. This research establishes validated frameworks for simulating, optimizing, and designing long-span DTBs, enabling resource-efficient infrastructure with enhanced performance predictability.