Performance of Stainless Steel Reinforced Concrete at High Temperature
Lead Research Organisation:
Brunel University London
Department Name: Civil Engineering
Abstract
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
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