Multi-story, old reinforced concrete (RC) structures with a “soft-story” on the ground floor, sustain considerable damage to the soft story during earthquakes due to the presence of masonry infills in the upper stories. Aspects of such masonry infill–RC frame interaction are briefly discussed and a particular retrofitting scheme for the soft story is studied. It consists of RC infills, added within the bays of the ground floor frames and combined with RC jacketing of the surrounding frame, aiming to avert such soft-story deficiency. The impact of such a retrofit is studied through the measured response of 1/3 scaled single-story, one-bay frames subjected to cyclic seismic-type horizontal loads. It is shown that this retrofit results in a considerable beneficial increase in stiffness, strength, and plastic energy consumption. The importance of the presence of effective steel ties connecting this RC infill with the surrounding frame is also demonstrated. In order to achieve these desired beneficial effects to such vulnerable buildings, additional design objectives are established with the aim of avoiding premature failure of the RC infill panel and/or fracture of the steel ties and to protect the surrounding RC frame from undesired local damage. A numerical methodology, which is validated by using the obtained experimental results, is shown to be capable of predicting reasonably well these important response mechanisms and can therefore be utilized for design purposes.

The total water needs of the city of Athens are supplied through the Mornos aqueduct. The Mornos aqueduct includes series of tunnels, siphons, and open R/C (reinforced concrete) canal segments. On the 29th of March 2011, sudden failure of the Mornos aqueduct took place causing interruption of the water supply. The failure has occurred in the Taxiarches canal of the Mornos aqueduct. It resulted in failure and displacement of the segmental parts of the aqueduct in a region spanning 80 m. The failure of the canal occurred in a zone of sharp morphology, at the front of an overthrust, vulnerable to erosion. A numerical investigation was carried in an effort to interpret the mechanism that caused the failure. The soil–structure interaction of the foundation conditions in respect to the segmental superstructure of the aqueduct is studied utilizing numerical simulation tools. The finite-element numerical analysis that was carried out includes two research fields. Initially, the role of the joint interface between articulated segments was investigated. Subsequently, the behavior of the whole numerical simulation of the aqueduct including the joint interfaces between segments were studied. Different numerical analysis was carried out to evaluate numerically the failure scenario. It was numerically established that the high water level in the surveillance road next to the aqueduct and the nonuniform subsoil condition of the foundation of the aqueduct raised the vulnerability of the structure. The numerical simulation proposed in the current study could be a useful tool for the inspection of articulated open channels for the avoidance of activation of similar failure mechanisms.