<p>Transit Oriented Developments’ (TOD) smooth integration with existing metro networks is a key aspect of their design, as they are located above, very close or even directly connected to existing underground metro structures. This poses a significant challenge to their structural and geotechnical design, which needs to consider and address a number of different issues, e.g. current condition of the existing metro stations &amp; tunnels, station structural system, metro-to- TOD connection, use of transfer systems, induced displacements to stations, tunnels &amp; movement joints, impact to the tracks, etc., as well as induced vibrations in the TOD buildings because of the metro operation. In this paper, the most significant aspects of these issues are shortly presented and discussed. The most common and effective ways to address them are also reviewed.</p>

Contemporary metro transport systems present unrivaled efficiency for the commuting population. The development of the urban environment is interwoven with the metro transit systems. The transit-oriented development (TOD) is an upcoming topic in the design of the contemporary and of the future city and metro system alike. It entails the development of a microcell of the city centered around the metro station. Typically, bulky TOD buildings rise over and around the station and tunnel. The structural engineering aspect of these mega projects is highly complex. Major part of the complexity is due to complicated interactions between the oversite building and the underlying tunnel or station with its track-rail system. A significant number of issues arise, like methods to bridge over the tunnel or station, structural isolation, induced displacements to the track-rail system, tunnel movements and impact to tracks, vibration induction to the TOD building, and a plenitude of similar problems. It is highly important to design a structural monitoring system that will provide a validation tool of the structural-dynamic performance of the closed system TOD-tunnel/station. The distilled experience from international projects is presented.

<p>The seismic performance of RC elements can be significantly impaired by inadequate lap-splicing of their reinforcing bars. In this paper the main findings of an experimental investigation of this influence are presented. Two rehabilitation techniques by means of external confinement of lap- splices are also examined. Cyclic tests on twelve (12) column-like specimens were performed. Four</p><p>(4) types of specimens were tested, one (1) with no reinforcement lap-splicing and three (3) with lap-splicing of their longitudinal reinforcement inside their critical regions (plastic hinges). For each type different lap-lengths were used. All specimens had the same geometry and reinforcement detailing. The tests were fully instrumented and monitored. The experimental results of this study are presented hereafter. Conclusions regarding the shear response, the hysteretic energy dissipation and the effectiveness of the strengthening techniques used are made.</p>