ABSTRACT
ABSTRACT In 2011 one of the cantilevered galleries of a high rise residential building in Leeuwarden, the Netherlands (constructed in 1965), fell down. In the late 60s and the mid-70s, a significant amount of reinforced concrete structures were built and nowadays suffer severely from varying concrete damaging mechanisms. In more than 50% of the cases, corrosion is the main deteriorating mechanism. Furthermore, the cause of the failure of the balcony lies in a combination of (i) inaccurate execution and inappropriate positioning of the reinforcement rebars, (ii) a higher load on the structural element and (iii) partial corrosion (pitting) of the concrete steel. In this present case study three reinforced concrete high rise buildings, situated near Brussels and whose design dates from 1963, are being investigated thoroughly by means of a protocol based on CUR Publication 248. These buildings consists of 17 floors, and have a different orientation. The prefabricated balconies of the building, who are the solely entrance path to the apartment units, have a length of 33 m per floor and represent a total area of approximately 2500 m2. By means of the four-step inspection protocol, the structural safety of the balconies is being evaluated and the residual bearing bending capacity is determined according to the Eurocode and fib Model Code regulations. It has to be determined whether the structural integrity of these reinforced concrete elements is endangered. The influence of concrete strength class, steel quality and rebar position is being identified for this particular case by means of a sensitivity analysis. By combining several non-destructive (rebar locator, rebound hammer, corrosion potential meter) and destructive techniques (core drilling and determination of chloride profile and carbonation depth) the risk of failure of the cantilevered balconies is estimated and potential danger zones are identified, in order to come to an appropriate building repair strategy.
