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

混凝土在火灾下的性能与常温下的性能有很大的不同。因此，人们对混凝土进行了大量的研究，通过研究和实验，对混凝土的理解也取得了很大的进展。但是，混凝土作为建筑材料，一直处于不断改进的状态。这导致了各种各样的产品，可以与越来越多的添加到混凝土中以改变其性能的外加剂一起使用。纤维增强聚合物已成为工程领域最大的突破之一。在过去的几十年里，碳纤维增强聚合物（CFRP）与自固结混凝土（SCC）的使用变得越来越普遍。这主要是由于CFRP的非腐蚀性。这意味着可以显著减少腐蚀保护所需的覆盖量。其他优点包括CFRP的高强度，这将使混凝土元件更坚固。所有这一切使得薄壁预应力混凝土构件可以用作建筑物立面的承重结构。然而，这些构件的使用一直局限于火灾不是一个大问题的区域，例如建筑物立面。这是由于高性能自密实混凝土（HPSCC）在高温下易于爆裂。尽管这是相对众所周知的，对这个问题的研究是稀缺的。此外，研究表明，CFRP筋和混凝土基体之间的粘结在高温下减少/丧失。这也是广为人知的，但没有足够的研究已经进行，以确定为什么是这样，以及如何进行的过程到底展开。因此，这项研究的目的将是了解剥离的剥离机制的剥离HPSCC和开发一种抗剥离形式的HPSCC，可以用作建筑物内部的承重项目。它还将侧重于了解在高温下CFRP和混凝土之间的粘结强度降低，以建立基于降低粘结强度的设计标准。

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.