All-glass structures have become increasingly popular with architects and builders in recent years. Glass surfaces are getting larger and more impressive to obtain maximum transparency for buildings. The supporting structure of glass facades, glass roofs or walk-on glazing is usually made of metal, justified in the fire protection requirements. To increase the transparency of the whole structure, load-bearing glass structures are getting more and more important. However, their use is currently still limited regarding concerns about its performance in case of fire. Fire tests need to be carried out to examine the load-bearing behaviour of glass beams exposed to fire. Due to the high costs and the high environment pollution caused by fire tests, preliminary examinations in form of simulations could be a solution. This paper describes the design of a numerical model to calculate the heat flow through glass beams under fire load. The model was validated using the results of experimental examinations. By means of the validated model, a parametric study was carried out to vary the parameters of the glass beam such as glass thickness, glass composition and interlayer thickness. This creates the opportunity to pre-select variations before the experimental examinations.