A bridge deck widening technology through rationally combining steel ribbed cantilever support-bottom reinforcement steel plate
[Objective]The construction of widening bridge decks often encounters several challenging issues,for instance,the longitudinal cracks occurring at the intersections between the new and existing sections of the bridge,and the transverse cracks appearing within the widened portions of the bridge.A proper addressing of these issues by enhancing and refining the methods for widening bridge decks constitutes a highly significant aspect of bridge engineering.Through the improvement and optimization of structural design and construction,it is feasible to ensure the bridge integrity and longevity and thereby consolidate its overall safety and performance.[Methods]Based upon the deck widening project for the first cross-sea bridge in China-Xiamen Bridge,the proposed approach rationally combines the strengths of several deck widening methods,namely,steel-concrete composite beam,orthotropic steel cantilever plate,and the bottom reinforcement plate.According to the proposed methodology,the cast-in-place concrete slab is employed as the bridge deck,and a wet connection is adopted to link the original and added parts of the bridge deck.The bridge widening parts are sustained by successive steel ribbed cantilever supports,which are also severe as the permanent formworks for the cast-in-place bridge deck concrete.Meanwhile,a three-dimensional finite element study conducted on the bridge deck expansion of the China-Xiamen Bridge yields crucial insights into the structural behavior and two reinforcement strategies employed.[Results]The investigation meticulously examines the effects of adjusting the spacing between adjacent steel ribbed cantilever supports on the distribution of tensile stress within the enlarged concrete bridge slab.The results indicate that there is a positive correlation between the layout spacing of the extended steel ribbed cantilever support structure(ranging from 0 to 0.5 meters)and the deflection of the bridge deck,as implies that as the spacing of the steel ribbed cantilever support increases,so does the deflection.In the mean time,the utilization of bottom reinforcement plates bolsters the overall stiffness of the superstructure,thereby facilitating the redistribution of stress within the stressed reinforcement and alleviating the stresses incurred by the construction reinforcement within the bridge.These interventions collectively contribute to enhancing the stress state of the retrofitted bridge.The finite element stress simulation results confirm the substantial safety requirement for the bridge retrofit and testify the efficacy of the proposed strategy.By mitigating tensile stress within the concrete components of the widened section,the proposed approach serves to attenuate the risk of crack initiation and propagation,thereby fortifying the structural integrity and extending the longevity of the bridge.Moreover,the finite element simulation further validates the sufficiency of the integrated reinforcement methodology in fulfilling the prescribed criteria for both stiffness and strength concerning the broader concrete deck slab.This substantiates the structural reliability and pragmatic viability of the proposed bridge deck widening strategy and proves its capability to withstand anticipated loading conditions and meet stringent engineering standards.[Conclusions]On the basis of the widening and reconstruction project of Xiamen Bridge,this work introduces a bridge deck widening strategy as a synthesis of steel ribbed cantilever supports and bottom reinforcement plates.The overall deflection of the bridge after widening,steel reinforcement stress,concrete stress,and steel support system stress are systematically investigated by three-dimensional finite element simulation.The influence of the spacing of the ribbed steel cantilever support arrangement on the stress and deformation distributions is disclosed.The proposed extended ribbed steel cantilever support-bottom reinforcement plate combination support system exhibits lightweight and aesthetically pleasing features.It significantly improves the bearing capacity of the widened bridge deck structure and has been successfully implemented in the bridge deck widening construction of Xiamen Bridge,which also offers valuable insights for similar bridge widening and reconstruction projects.
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