Abstract
The hollow slabs strengthened by ultrahigh performance concrete (UHPC) composite beam show many advantages over traditional reinforcement methods. In this paper, full‐scale model load tests were carried out on an nonstrengthened prestressed concrete hollow slab and an UHPC‐strengthened prestressed concrete hollow slab, comparing the load deflection, crack width, bearing capacity, deformation resistance, and self‐vibration frequency of the two. Static loading experimental results indicate that UHPC enhances the overall performance of prestressed concrete hollow slabs by decreasing deflection and crack width and improving bearing capacity. The strengthening effects of UHPC on a prestressed concrete hollow slab’s flexural behavior are also discussed, such as deflection, crack width, bearing capacity, deformation resistance, self‐vibration frequency, flexural behavior, and cracking load. Deflection and crack width under a load of 800 kN decreased by 45.8% and 56.3%, respectively, and the initial self‐vibration frequency, ultimate bearing capacity, and cracking load increased 19.2%, 21.4%, and 50%, respectively. The plane assumption can be made generally throughout the overall test process while using UHPC strengthening, which significantly constrains crack width and improves stiffness and deformation capacity. The UHPC layer and the prestressed concrete hollow slab were connected by shear studs to produce a good composite action between them, and the bending performance and bearing capacity of the whole structure were clearly improved. In addition to experiments, a validated numerical model is developed to verify the flexural performance of hollow slab strengthened by UHPC.
Highlights
Prefabricated reinforced concrete or prestressed concrete hollow slab is widely used in the construction of expressways and urban bridges, because it offers the advantages of standardized design, integrated production, assembly construction, low cost, low building height, overall beauty, clear structure force, and so on
Under 800 kN load, the midspan deflection of ultrahigh performance concrete (UHPC)-strengthened prestressed concrete hollow slab is about 45.8% lower than that of without strengthened prestressed concrete hollow slab. e stiffness of UHPC-strengthened prestressed concrete hollow slab is greater than that without strengthened prestressed concrete hollow slab, indicating that UHPC strengthening can effectively improve the stiffness of prestressed concrete hollow
Slab. e maximum deflection of Specimens S2 and S3 exceeded that of Specimen S1 by 119% and 81.9%, respectively, with the ductility of Specimen S2 exceeding that of Specimen S3, indicating that the strengthening effect of carbon fiber reinforced polymer (CFRP) mainly improves the tensile capacity of steel bars
Summary
Prefabricated reinforced concrete or prestressed concrete hollow slab is widely used in the construction of expressways and urban bridges, because it offers the advantages of standardized design, integrated production, assembly construction, low cost, low building height, overall beauty, clear structure force, and so on. Xu et al [21] used UHPC mixed with polymer fiber to strengthen plain concrete beams by using a cast-in-place plain UHPC layer to reinforce their underside, greatly improving their bending capacity while inhibiting the development of cracks. Deng and Zhang [25] verified that the bottom of a reinforced concrete beam strengthened with a thin layer of UHPC exhibited greatly improved bending capacity and reduced midspan deflection. E purpose of this paper is to study the influence of UHPC strengthening on the bearing capacity, crack inhibition, bending stiffness, flexural behavior, natural frequency, and overall consistency of prestressed concrete hollow slabs through full-scale model testing while theoretically calculating cracking load and bearing capacity, to prove that UHPC has a notable strengthening effect on prestressed concrete hollow slabs.
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