Performance-based approach, introducing a new two-phase computational model for determining the response of prestressed hollow-core concrete slab exposed to natural fire including heating and cooling phase, is presented. Firstly, the two-dimensional coupled hygro-thermo-chemical model is used to determine time dependent temperature and moisture field in the characteristic cross-section of the concrete hollow-core slab during fire. In addition, the influence of opening on the temperature distribution over prestressed hollow-core concrete slab is accounted for. Secondly, stress–strain state of prestressed concrete hollow-core slab is determined with a newly developed one-dimensional geometrical and material non-linear model, which includes a slip between concrete and tendon. Temperature dependent mechanical properties of concrete, tendon and bond stiffness are accounted for in the model. Model validation showed that the presented two-phase computational model is suitable for the analysis of prestressed hollow-core concrete slab exposed to natural fire. Furthermore, parametric studies revealed that heat exchange between the concrete section and the opening has a significant influence on the development of temperatures in the slab, particularly in the cooling phase, and consequently also on the development of slab displacements. In addition, it was identified that accounting for the slip between concrete and tendon enables the determination of the bond stress distribution and evaluation of the load bearing capacity of the contact.

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预应力混凝土空心板自然火灾计算模型

介绍了基于性能的方法，引入了一种新的两阶段计算模型，用于确定暴露于自然火灾（包括加热和冷却阶段）的预应力空心混凝土板的响应。首先，利用二维耦合的湿热化学模型来确定火灾期间混凝土空心板特征截面中随时间变化的温度和湿度场。此外，还考虑了开孔对预应力空心混凝土板温度分布的影响。其次，用新开发的一维几何和材料非线性模型确定预应力混凝土空心板的应力应变状态，其中包括混凝土和筋之间的滑移。混凝土的温度相关机械性能，模型中考虑了肌腱和粘结刚度。模型验证表明，所提出的两阶段计算模型适用于暴露于自然火灾的预应力空心混凝土板的分析。此外，参数研究表明，混凝土截面和开口之间的热交换对板中温度的发展有重大影响，特别是在冷却阶段，因此也会对板位移的发展产生影响。此外，还确定考虑混凝土和筋之间的滑动可以确定粘合应力分布并评估接触的承载能力。模型验证表明，所提出的两阶段计算模型适用于暴露于自然火灾的预应力空心混凝土板的分析。此外，参数研究表明，混凝土截面和开口之间的热交换对板中温度的发展有重大影响，特别是在冷却阶段，因此也会对板位移的发展产生影响。此外，还确定考虑混凝土和筋之间的滑动可以确定粘合应力分布并评估接触的承载能力。模型验证表明，所提出的两阶段计算模型适用于暴露于自然火灾的预应力空心混凝土板的分析。此外，参数研究表明，混凝土截面和开口之间的热交换对板中温度的发展有重大影响，特别是在冷却阶段，因此也会对板位移的发展产生影响。此外，还确定考虑混凝土和筋之间的滑动可以确定粘合应力分布并评估接触的承载能力。参数研究表明，混凝土截面和开口之间的热交换对板中温度的发展有重大影响，特别是在冷却阶段，因此也会对板位移的发展产生影响。此外，还确定考虑混凝土和筋之间的滑动可以确定粘合应力分布并评估接触的承载能力。参数研究表明，混凝土截面和开口之间的热交换对板中温度的发展有重大影响，特别是在冷却阶段，因此也会对板位移的发展产生影响。此外，还确定考虑混凝土和筋之间的滑动可以确定粘合应力分布并评估接触的承载能力。