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预应力混凝土板因具备自重轻、跨度大等特点,广泛应用于建筑结构和桥梁结构中。但是,当这种结构受到火灾荷载作用时,其承栽能力就会大幅下降。在高温下,混凝土和预应力筋的力学性能都会劣化,进而造成板的大挠度变形甚至破坏。本文对后张无粘结简支预应力板建立了数值分析模型,其中混凝土和预应力筋采用实体单元模拟,受力筋和分布钢筋采用桁架单元模拟。模型中材料的力学特性和热工特性参数取自文献[15]。采用文献中的试验结果验证了该数值模型的可靠性,并进一步研究了混凝土受热膨胀系数、板的不同区域受火和不同的火灾场景等因素对火灾荷载作用下后张无粘结预应力混凝土简支板的挠度以及预应力的影响,得出了初步结论。
Prestressed concrete slab because of its light weight, large span and other characteristics, are widely used in building structures and bridge structures. However, when this structure is subjected to a fire load, its load-bearing capacity is significantly reduced. Under high temperature, the mechanical properties of concrete and prestress tendons will deteriorate, which will cause the plate to deform or even destroy. In this paper, the numerical analysis model of post-tensioned unbonded simply supported prestressed slab is established, in which the concrete and prestressing tendons are simulated by solid elements, and the reinforced and distributed reinforcing bars are simulated by truss elements. The mechanical and thermal properties of the material are taken from the literature [15]. The reliability of the numerical model is verified by the experimental results in the literature. The thermal expansion coefficient of concrete, the fire exposure in different areas of the slab and the different fire scenes are also investigated. The post-tensioned unbonded prestressed concrete The deflection of the simply supported plate and the influence of the prestress, the preliminary conclusion is drawn.