Designing a steel threshold for fire doors : Identification of important aspects

The purpose of this study is to identify important aspects to consider when designing a threshold for fire doors. At the time of writing the authors found limited published research regarding thresholds for fire doors, most research in the area had the door in focus. The threshold does however serve an important function for the fire protection system and therefore additional research is required. This study was made to contribute to improving the future designs of fire door thresholds. The goal is to give insights that can help improve the fire protection system of buildings, increasing the chance of survival for the people in the building if a fire would occur while also making sure that the threshold is viable for the manufacturer to produce. Sustainability and the useability of the threshold during normal use is also investigated. What design choices that are affecting each aspect is discussed. This is done by answering the question: What are important aspects to consider for manufacturability, environmental sustainability and usability when designing a steel threshold for fire doors? The work was carried out as a case study at the company CH Industry working with their section for fire and security doors production. A qualitative approach was used where data was gathered by analysing previous articles and other websites. Empirical data was gathered through observations at a guided factory tour of the case company along with an interview of the designer of the company’s current thresholds. Insight was gathered through designing a new threshold for the company, taking their wants into consideration. The new threshold was developed up to and including the detail design phase. This included thermal and static simulations to get an idea of the threshold’s performance. The study’s conclusion includes insights into important aspects that should be taken into considerations when designing a threshold for fire doors. It was found that standards, certifications and classifications should be considered during the design phase, how is the threshold going to fulfil these. It was found that the seal between the door leaf and threshold was the most important to fulfil them. What considerations when deciding on what material to use was also discussed, depending on the use case and what is the most important to the user. What design decisions that affect useability during normal use was also discussed, how design choices such as the threshold height and bevelled sides can make it easier for people with reduced mobility to get over the threshold and reduce the risk of tripping. What impacts the manufacturability of the threshold was also found, such as how the threshold design can be limited by the available machines in the factory and the order of the machines in the production line can be considered to make the manufacturing process more efficient. How the thickness of the material can allow for alternate manufacturing methods was also found. How fire tests need to be made to confirm the performance of the threshold is also discussed. It was found that simulations can be used instead of physical testing during the design phase to reduce the number of physical prototypes needing to be made. Finally, the environmental impact of design choices is explored. Adhesives can be avoided to reduce the environmental impact. The material choice also has a major impact as well as the manufacturing process. The design of the threshold decides if adhesives can be avoided, what material is used and what manufacturing process that can be used.