Assessment of cantilevered concrete balconies by means of practically oriented evaluation tools

Abstract

Facing the aging building stock, challenging times can be expected with a sharp increase of reinforced concrete buildings requiring maintenance, repair and/or replacement. For the condition assessment of existing reinforced concrete structures an in-depth and reliable inspection strategy and evaluation is essential to come to a durable and service-life extending repair strategy. A stepwise protocol to evaluate the condition and remaining bearing capacity of cantilevered reinforced concrete (RC) balconies is presented in this paper. Corrosion causing the reduction of the steel section, incorrect positioning of the reinforcement and/or higher loads are the main reasons service life might not be reached or the failure of the balcony can occur. As mentioned in EN 1504-9 and NEN 8700, an adequate diagnosis prior to repair showing the cause and extent of the damage is important (i) to determine the actual bearing capacity, (ii) to make an estimation of the residual lifespan and (iii) to select a durable repair technique and/or define maintenance requirements. In this paper a newly developed protocol for the assessment of the condition and the bearing capacity of the cantilevered RC balconies of a high-rise residential building is demonstrated. A semi-probabilistic method is used by applying partial safety factors based on Eurocode guidelines and fib Bulletin 80. The condition of the structure is determined based on NEN2767 regulations. As corrosion is the main contributor to the degradation of existing concrete structures, a chloride contaminated building with damaged reinforced concrete balconies is selected as case study in order to demonstrate the applicability of the developed protocol and tools.