Wie heiß wurde der Spannstahl der Brücke über die BAB 2 während des Brandes am 16. 07. 2004?

What was the maximum Temperature of the prestressing Steel of the Bridge over the BAB 2 during the Fire at July 16, 2004? At July 16, 2004 a bridge over the BAB 2 was damaged by fire. The practicability to repair the brigde was mainly determined by the maximum temperature of the prestressing steels during the fire. By computer simulations and chemical analysis it could be determined, that the prestressing steel has not reached a temperature of 200 °C. Plastic deformations and a permanent loss of strength could therefore be excluded with great certainty. The bridge can be repaired with relative low expense.     

Nachhaltiges Sanieren? Zur ökologischen Effektivität und ökonomischen Effizienz energetischer Sanierungsmaßnahmen im Altbau am Beispiel von Dachsanierungen

Sustainable Restoration? About the ecological effectiveness and economical efficiency of restoration measures on old buildings, using roof restoration as an example. Of all CO₂ emissions caused by private housing, 90 % are from old buildings. This makes progress mandatory to leverage the emission reduction potential of this part of the building sector. However, in order to truly achieve CO₂ emission reduction, it is advisable to assume a holistic perspective when comparing renovation measures. This paper compares variants of renovation measures with respect to their ecological effectiveness and economical efficiency. Examples will be taken from roof renovation to demonstrate the proposed procedure.     

ThermoShield – ein Beitrag zur Wärmedämmung?

ThermoShield – a contribution to thermal insulation? For some time now, so called thermal coatings are being introduced onto the market. Advertisement to these products announce that these coatings reduce heating energy requirement in buildings considerably. These coatings are facade paintings, e.g the product “ThermoShield”, to which microscopic small ceramic bubbles are added. In the product data to these coatings, a heating energy saving up to 30% are mentioned. The manufacturer impute these saving to different effects of the “ThermoShield” coating. To check the upper mentioned promising product properties, the thermal behaviour of test specimens coated with “ThermoShield – Exterieur” are being studied within the scope of a research work at the University of Hannover. The evaluation of the measurement results showed, that the specimens coated with “ThermoShield” did not have the thermal properties expected and that this coating do not show any of the promised thermal insulating properties.     

Untersuchung des Wärmeschutzes von Außenecken über unbeheizten Kellern in Wohngebäuden – die Achillesferse von massiven Außenwänden mit äußerer Wärmedämmung?

Examination of the thermal insulation characteristics of external corners above unheated basements in dwellings – the Achilles' heel of heavy‐weight external walls with thermal insulation on the outside? External walls in dwellings consist often of a heavy‐weight wall and a thermal insulation fixed outside. With this construction the insulation of the external wall is separated by the plinth of the external wall from the thermal insulation incorporated in the slab above an unheated basement. This results in a thermal bridge along the edge of the basement slab. The most critical point of the construction with regard to thermal protection occurs at the exterior corner at ground floor level, where two linear thermal bridges overlay. For this reason the minimum inner surface temperature of the corner is used to estimate the heat protection of the construction. A number of calculations of the minimum temperature at the interior surface of this three dimensional thermal bridge is performed to evaluate the parameters of the adjacent construction details which affect the minimum temperature at the inner surface of the corner. To reach the minimum temperature at he inner surface of the corner of 12.6 °C demanded by the German standard DIN 4108‐2 as the minimum requirement of heat protection for thermal bridges, thermal resistances of the whole wall construction much higher than 1.2 m²K/W are necessary. For this construction type of exterior walls a thermal resistance of 1.2 m²K/W as demanded in table 3 of the German standard DIN 4108‐2 as a minimum heat insulation for exterior walls can be shown to be insufficient to assure a minimum temperature of 12.6 °C at the inner surface of the corner at ground floor level. Thus it is proposed to add additional notes concerning this construction type in this standard.     

Dachentwässerungen im Zuge geänderter normativer Anforderungen und sich ändernder klimatischer Einwirkungen – eine Planungsaufgabe?

Roof drainage in the course of changed regulation require‐ments and changed climatic influences – a planning task? The roof and building drainage is supposed to take over the flaw‐less drain of rain water. Still, the roof drainage as planned is “only” designed for a rain of medium intensity. In order to prevent damages through rain of stronger intensity the possibility of an emergency drainage will be planned. The emergency drainage and the ensured roof drainage by regular maintenance are the main drainage requirements. With the new regulation generation, planning and structural design of gutters and fall pipes are first done using basis for assessment of hydraulic nature and statistically backed up rain fall data. Nevertheless, case studies show that there is not enough attention given to the planning and design of roof and building drainage. Not uncommon, the result is water damage to the structure. An analysis of the design method shows that even in this sensitive field of building construction – in opposition to static dimensioning of components – there are usually no safeties planned. However, on the tide of the evolving climatic changes, this would make sense inter alia to prevent overloading and damages.