Performance of Stainless Steel Reinforced Concrete at High Temperature

不锈钢是一种非常有用的结构材料，自1940年左右以来一直用于建筑行业的承载应用。与碳钢相比，它有几个优点，包括它的耐腐蚀性和良好的延展性，但是它的初始成本要高得多，因此需要谨慎使用。碳钢和不锈钢的主要区别在于合金元素的含量，主要是铬，它至少占不锈钢的12%。有许多不同的不锈钢等级取决于不同合金的百分比。由于其优异的强度、延展性、可焊性和耐久性，奥氏体和双相等级在结构应用中最常见。除了裸露的金属部分外，它们还可以与混凝土一起使用，以创建复合结构部分。对裸不锈钢在正常和极端载荷下的性能进行了大量的研究。这些材料的应力应变响应与碳钢的应力应变响应有很大的不同，因为它是高度非线性的，没有明显的屈服点，并且具有极强的延展性。目前的项目主要关注不锈钢钢筋混凝土的性能。不锈钢在钢筋混凝土中的使用是非常有限的，欧洲规范2等设计指南中并没有对此进行任何规定。因此，有必要对不锈钢混凝土的性能进行进一步的研究，以利用和利用其优良的延性。除了它的非线性行为，不锈钢面临的第二个挑战是确定它在高温下在钢筋混凝土构件中的表现。对不锈钢钢筋的高温材料性能已有一些研究，但对结构构件的高温性能研究较少。这个研究项目将调查这个地区。研究发现，在550℃以上，奥氏体不锈钢通常比碳钢保持更高的室温强度比例，并在所有温度下保持更高的刚度比例。根据上述背景，本研究的主要目的如下：制定不锈钢钢筋在暴露于火中的混凝土中的使用指南。生产具有成本效益和减少维护的不锈钢钢筋混凝土结构。突出高温下混凝土中不锈钢钢筋的性能。探讨在不考虑腐蚀裂缝的情况下，是否可以减少钢筋的混凝土保护层。在这项工作中，将使用ABAQUS软件开发一个有限元模型来表示暴露在标准火灾（ISO 834火灾）中的不锈钢钢筋混凝土梁。我的研究将包括以下里程碑开发一个有限元（FE）模型，能够模拟火灾中钢筋混凝土梁的真实行为。了解不锈钢钢筋在火灾中的行为，包括建立合适的材料模型。将该材料模型结合到有限元模型中，对不锈钢钢筋混凝土梁在火灾条件下进行分析。进行参数研究，以评估最显著参数的影响。在研究结果的基础上制定不锈钢钢筋混凝土的使用指南

Stainless steel is a very useful structural material which has been used for load-carrying applications in the construction industry since around 1940. It has several advantages compared with carbon steel including its corrosion resistance and excellent ductility however it is considerably more expensive in terms of initial cost and therefore needs to be employed carefully. The main difference between the composition of carbon steel and stainless steel is the amount of alloying elements, primarily chromium which makes up at least 12percent of stainless steel. There are a number of different stainless steel grades depending upon the percentage of different alloys. The austenitic and duplex grades are the most common in structural applications owing to their excellent strength, ductility, weldability and durability. In addition to bare metallic sections, they can also be employed together with concrete to create a composite structural section. There has been considerable research done on the behaviour of bare stainless steel under normal and extreme loads. The stress-strain response of these materials is quite different to that of carbon steel in that it is highly nonlinear, does not have a distinct yield point, and is extremely ductile. The current project is focussed on the behaviour of stainless steel reinforced concrete. The use of stainless steel in reinforced concrete is very limited, and the design guidance such as Eurocode 2 does not include any provisions for this. Therefore, it is imperative to undertake further research into the behaviour of stainless steel reinforced concrete with a view to harnessing and exploiting the excellent ductility on offer. In addition to its nonlinear behaviour, the second challenge for stainless steel is to determine how it behaves in reinforced concrete members under high temperatures. There is some research already done on the elevated temperature material properties of stainless steel rebar, but not the structural members. This research project will investigate this area. It has been found that austenitic stainless steel generally retains a higher proportion of its room temperature strength than carbon steel above 550 degrees C, and a higher proportion of its stiffness at all temperatures. Objectives In light of the background provided above, the main aims for this research are as follows: To develop some guidelines for the use of stainless steel reinforcement in concrete exposed to fire. To produce cost-effective and reduced maintenance stainless steel reinforced concrete structures. To highlight the properties of stainless steel reinforcing bar in concrete under high temperatures. To investigate if the concrete cover for the reinforcement can be reduced as corrosion-induced cracks can be ignored. Methodology In this work, a finite element model will be developed to represent of stainless steel reinforced concrete beam which is exposed to a standard fire (the ISO 834 fire) using the ABAQUS software. My research will comprise the following milestones Developing a finite element (FE) model which is capable of simulating the true behaviour of a reinforced concrete beam in fire. Developing an understanding of the behaviour of stainless steel rebar in the fire, including establishing a suitable material model. Incorporating this material model into the FE model to enable analysis of a stainless steel reinforced concrete beam under fire conditions. Conduct a parametric study to assess the influence of the most salient parameters. Develop guidelines for use of stainless steel reinforced concrete on the basis of the results