Comparative analysis of the seismic performance of unreinforced masonry buildings using globigerina limestone and hollow concrete blockwork

Abstract

This dissertation investigates the seismic performance of unreinforced masonry (URM) buildings with soft-storey basements, comparing structures constructed using Globigerina limestone and Hollow Concrete Blockwork (HCB). The research problem addresses the disparity in seismic resilience between these two construction materials. The methodology involves numerical modelling and comparative analysis using non-linear static pushover analysis with 3D Macro. Virtual models of masonry structures built with HCB bonded with M5 mortar and Globigerina limestone bound with M2 mortar were developed to simulate seismic forces and assess structural performance. Key findings reveal that HCB structures consistently outperform Globigerina limestone structures in terms of resilience and safety factors across various seismic conditions and ground types. Comparative analysis of pushover curves indicates that, for the same horizontal sway displacement at the top storey, Globigerina limestone structures experience higher horizontal base shear forces compared to HCB structures. Despite this, safety factors suggest that HCB aggregates enable structures to achieve greater building heights than Globigerina limestone aggregates. This seemingly counterintuitive result is due to HCB aggregates attracting less horizontal base shear force, which reduces seismic force demand on the structure. Consequently, structures with HCB aggregates undergo lower stress and strain, allowing for increased height without compromising safety. Additionally, HCB structures exhibit better ductility and energy dissipation, maintaining steadier performance post-peak. The critical impact of structural configuration on seismic performance was also highlighted, emphasizing the importance of symmetrical design in enhancing structural resilience.