Fire Behaviour of Self-Prestressed Concrete Slabs Reinforced with Carbon Fibre Rein- forced Polymer Tendons

混凝土在火灾下的行为与在环境温度下的行为有很大的差异。这使得人们对这一课题进行了大量的研究，通过研究和实验对这一课题的认识也取得了很大的进展，但混凝土作为一种建筑材料一直处于不断完善的状态。这导致了各种各样的产品，这些产品可以与越来越多的外加剂一起使用，这些外加剂被添加到混凝土中以改变其性能。纤维增强聚合物已经成为工程界最大的突破之一，在过去的几十年里，碳纤维增强聚合物(CFRP)和自固结混凝土(SCC)的使用变得越来越普遍。这主要是由于CFRP的非腐蚀性造成的。这意味着可以显著减少防腐所需的盖子数量。其他好处包括CFRP的高强度，这将使混凝土构件更加坚固。所有这些都使得薄壁预应力混凝土构件有可能被用作建筑立面的承重结构。然而，这些构件的使用一直保持在火灾不是很大问题的地区，如建筑立面。这是由于高性能自固结混凝土(HPSCC)在高温下容易发生爆炸剥落。尽管这一点相对来说是众所周知的，但对这个主题的研究却很少。此外，研究表明，CFRP筋与混凝土基质之间的粘结在高温下会减少/丢失。这也是众所周知的，但还没有进行足够的研究来确定为什么会发生这种情况，以及这个过程是如何准确展开的。因此，本研究的目的是了解HPSCC剥落的机理，并开发一种可以作为建筑物内部承重物品的HPSCC抗剥落形式。它还将重点了解CFRP与混凝土之间在高温下的粘结强度降低，以便建立基于粘结强度降低的设计标准。

The behavior of concrete under fire varies greatly to that under ambient temperatures. This has led to a vast amount of research being carried on this subject, and a huge amount of progress has been made in terms of understanding the subject through research and experiments.Concrete, however, has been in a constant state of improvement as a building material. This has led to a wide range of variation of products that can be used with an ever growing list of admixtures that are added to concrete to change its properties. Fiber Reinforcing Polymers have emerged as one of the biggest breakthroughs in the world of engineering.The use of carbon fibre reinforcement polymers (CFRP) with self consolidating concrete (SCC) has become more common in the past couple of decades. This is mainly due to non corroding nature of CFRP. This means that the amount of cover that is required for corrosion protection can be significantly reduced. Other benefits include the high strength of CFRP which will make the concrete element much stronger. All of this together has made it possible for thin-walled prestressed concrete elements to be used as load bearing structures in building facades.The use of these elements, though, has been kept to areas where fire is not a big concern such as building facades. This is due to the fact that high performance self consolidating concrete (HPSCC) tends to spall explosively at elevated temperatures. Despite this being relatively well known, research into this subject is scarce. Furthermore, studies have shown that the bond between CFRP tendons and concrete matrix is reduced/lost at elevated temperatures. This is also widely known but not enough research has been carried out to determine why is this and how does the process unfold exactly.The purpose of this research will, therefore, be to understand the spalling mechanism of spalling of HPSCC and to develop a spalling resistant form of HPSCC that could be used as load bearing items within the interiors of buildings. It will also focus on understanding the bond strength reduction between CFRP and concrete at elevated temperatures in order to establish design criteria based on reduced bond strength.