预应力高延性混凝土钢管桁架叠合板受弯性能研究OA

To address existing challenges in current composite slabs,such as excessive self-weight,low cracking strength,and dense temporary supports,a highly ductile prestressed concrete composite slab with steel tube trusses was proposed,and the flexural performance of specimens during the service stage was studied.One cast-in-place slab and four composite slabs were designed,and four-point flexural tests were conducted to analyze the failure modes,load-deflection curves,and strain distributions.The results indicate that,under a 6 m unbraced span,the bottom plates of the precast components do not exhibit any cracking,and the mid-span deflection is less than 20 mm,thereby satisfying the construction-phase requirements.The bridging effect of PVA fibers effectively reduces both the crack spacing and crack width.The precast slab collaborates with the cast-in-place concrete,ensuring optimal shear performance at the composite interface without requiring special treatment.The peak deflection of the unbraced composite slab is approximately 70％of that of the adequately supported composite slab,and their peak loads are equivalent.Based on the test results,the key design issues related to highly ductile prestressed concrete composite slabs with steel tube trusses were theoretically analyzed,including the crack resistance and deflection checks of prefabricated components during the construction phase,as well as the bearing capacity,deflection,and normal serviceability limit state checks of the composite slabs during the service phase.Additionally,a two-stage coordinated design method was provided.