System-level post-construction structural assessment of 3D printed concrete facilities under seismic action

3D printed concrete (3DPC) is a transformative innovation in the construction industry allowing precision, speed, cost-reduction and sustainability augmented with formwork-less architectural flexibility. The primary focus of existing research and development in this field has been on the material composition, printing process and its robotic system to improve strength and durability of concrete produced using this technology alongside speed and precision. However, this technology finds application within a limited sphere of construction currently owing to its shift from the prevailing practice of conventionally cast concrete (CCC) in addition to the lack of any structural design guidelines or codal provisions. While a significant quantity of published research focuses on material-level and component-level studies on the subject, few studies address structural system-level investigation of structures built using 3Dconcrete printing technology. The current study examines the seismic behaviour of 3DPC structures at a system-level and conducts structural performance evaluation of such structures. Two real 3DPC structures were tested using a non-destructive approach under ambient conditions to extract their dynamic properties such as mode shapes and mode frequencies. Subsequently, the numerical models developed on a finite element analysis platform were calibrated to study the 3DPC structures at system-level, with an absolute maximum error of 11% between the experimentally and numerically obtained mode frequencies. The investigation revealed that despite the absence of specific seismic design guidelines, 3DPC structures can be promising in seismic performance owing to the higher strength-to-weight ratio achieved through shape optimisation. However, a provision of properly optimised structural reinforcement in 3DPC structures is required to ensure adequate ductility as suggested by the calculated Response Modification Factor due to ductility(R-factor) in the range of 1.4–2.3, significantly short of the design R-factor prescribed for ordinary RC structures.