Manfred Korzen

Protecting the structural integrity of composites in fire: Intumescent coatings in the intermediate scale

The fire behaviour of light-weight material used in structural applications is regarded as the main challenge to be solved for mass transportation. The task is to perform realistic experiments, including a mechanical test scenario under fully developed fires, to improve the material’s reliability in structural applications. Our approach utilises an intermediate-scale test set-up (specimen size 500 × 500 mm) to apply realistic compressive loads and fully developed fires directly to one side of a carbon-fibre-reinforced sandwich composite. Three different intumescent coatings were applied to sandwich structures and compared to a bench-scale study. The results emphasise intumescent coatings as a promising method to sustain fire resistance, multiplying the time to failure. Nevertheless, the realistic intermediate-scale test using severe direct flame application underlines the extremely short failure times when the actual composite components are tested without any additional insulation.

Structural integrity of sandwich structures in fire: an intermediate-scale approach

A test set-up in intermediate scale was conceived to investigate the structural integrity of materials under fire. The task was to develop a realistic test scenario targeting component-like behaviour. Carbon-fibre-reinforced sandwich specimens (500 × 500 × 20 mm) were used to examine failure mechanisms, times to failure and critical failure loads under compression. Fire tests were performed with fully developed fire applied to one side of the specimen by an oil burner. In a first test series, the applied load was varied, but the fully developed fire remained unchanged. In general, times to failure were short. Decreased load levels resulted in prolonged times to failure and led to a different failure mechanism. Results obtained in the test series were compared with a bench-scale study (150 × 150 × 20 mm) investigating identical material. The comparison clearly revealed the influence of size on the time to failure and the load-bearing capacity.

Experimental Research on the Load-Bearing Capacity of Partially Encased Steel Columns Under Fire Conditions

The composite steel and concrete columns are known to have enhanced fire behaviour when compared with bare steel columns. However there are still aspects that must be clarified, as the influence of the building surrounding structure on the fire resistance of the columns. In this paper, the results of fire resistance tests on partially encased steel columns carried out with two different experimental systems are compared. In one of the experimental systems, the building surrounding structure is materialised by a steel restraining frame, and in the other is performed by the so-called substructuring method. Due to the concept of hybrid substructuring, the entire building is decomposed in two parts: one is represented by the building element under test, whereas the remaining building is simulated numerically in a computer. The main conclusion drawn from this work was that the surrounding structure has a major influence in the development of axial forces in the test columns. Moreover, it was observed that the higher the non-dimensional axial restraint ratio the lower the critical time of the columns.

REAL-TIME 3-D VISUALIZATION OF SURFACE TEMPERATURE FIELDS MEASURED BY THERMOCOUPLES ON STEEL STRUCTURES IN FIRE ENGINEERING

Abstract The aim of this paper is to present some advanced techniques for monitoring thermocouples in the field of fire engineering. In a fire test structural elements like columns, beams or slabs are subjected to mechanical as well as thermal loadings. Whereas the mechanical loading is constant, the mean temperature in the furnace varies nearly monotonically as a function of time within 90 minutes between room temperature and 1000 °C. New technical standards as well as research purposes require the monitoring of 30 to 60 thermocouples and more. Although versatile data acquisition systems exist, there is a lack in representing these data during the test in their geometrical context. The method, which is proposed by the authors, uses some recent developments in computer graphics and numerical mathematics. By this method, the monitoring of the thermocouples is understood as a representation of a time-dependent 1-dimensional field, which is based on discrete measured values on a curved surface in 3-D space. Quantitative results of a column fire test are presented with a comparison of the classical and the new method.