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年以来一直用于建筑行业的承载应用。与碳钢相比，它具有几个优点，包括其耐腐蚀性和优异的延展性，但就初始成本而言，它要昂贵得多，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%。根据不同合金的百分比，有许多不同的不锈钢等级。奥氏体和双相钢由于其优异的强度、延展性、可焊性和耐久性，在结构应用中最为常见。除了裸露的金属型材外，它们还可以与混凝土一起使用，以创建复合结构型材。已经有相当多的研究做了在正常和极端负荷下的裸不锈钢的行为。这些材料的应力-应变响应与碳钢的应力-应变响应完全不同，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。目前的项目是集中在不锈钢钢筋混凝土的行为。不锈钢在钢筋混凝土中的使用非常有限，欧洲规范2等设计指南对此没有任何规定。因此，必须对不锈钢钢筋混凝土的性能进行进一步研究，以利用和开发所提供的优异延性。除了其非线性行为外，不锈钢的第二个挑战是确定其在高温下在钢筋混凝土构件中的行为。有一些研究已经做了高温材料性能的不锈钢钢筋，但没有结构构件。本研究项目将调查这一领域。已经发现，奥氏体不锈钢通常在高于550摄氏度时比碳钢保持更高比例的其室温强度，并且在所有温度下保持更高比例的其刚度。目的基于上述背景，本研究的主要目的如下：为火灾下混凝土中不锈钢钢筋的使用提供指导。生产具有成本效益和减少维护的不锈钢钢筋混凝土结构。重点介绍了高温下混凝土中不锈钢钢筋的性能。调查钢筋混凝土保护层是否可以减少，因为腐蚀引起的裂缝可以忽略不计。 方法在这项工作中，将开发一个有限元模型来表示不锈钢钢筋混凝土梁暴露在一个标准的火灾（ISO 834火灾）使用ABAQUS软件。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。将此材料模型转换为有限元模型，以分析火灾条件下的不锈钢钢筋混凝土梁。进行参数研究，以评估最显著参数的影响。根据结果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