Current bridge design codes stipulate that prefabricated T‐beam bridges must include intermediate diaphragms, with spacing not exceeding 10 m. However, the construction of these diaphragms entails extensive overhead work, elevated safety risks, and significant challenges in quality control. Therefore, safely and reliably reducing or even eliminating the use of intermediate diaphragms offers a promising approach to enhancing construction efficiency and quality. This study focuses on conventional T‐beam bridges and investigates the structural function and mechanical mechanisms of intermediate diaphragms through a combination of theoretical analysis, finite element simulations, and scaled model testing. Load effects in both longitudinal and transverse directions were evaluated for girder systems with and without diaphragms to assess their structural function and the mechanism behind longitudinal cracking in bridge decks. Key findings include: (1) Under current transverse load distribution theory, intermediate diaphragms affect longitudinal force response by ~10%, with limited influence on overall bridge design. (2) Diaphragms enhance load‐sharing among girders. Removing them increases the maximum vertical deflection by 13.5%, while longitudinal load changes remain minimal. However, the maximum transverse tensile strain in the deck slab increases by ~1.1–1.4 times. (3) Intermediate diaphragms reduce nonuniform deflection between beams, effectively decreasing the indirect transverse internal force in the bridge deck and cumulative tensile stress, which helps prevent longitudinal cracking. Enhancing deck slab stiffness can improve vertical shear resistance at the wet joint, reduce nonuniform deflection, and enable the design of T‐beam bridges without intermediate diaphragms.
Zhou et al. (Thu,) studied this question.