Masonry Infilling of RC Building Against Progressive Collapse in case of Loss of Column
Nikos Stathas1, Ioannis Karakasis2, Elias Strepelias1, Xenofontas Palios1,
Micheal Fardis3, Stathis Bousias3
1 PhD, Post-doctoral researcher, Structures Laboratory, Department of Civil Engineering,
University of Patras, Greece
stathas@upatras.gr
ilstrepelias@upatras.gr
xenpal@upatras.gr
2 MSc, Post-graduate Researcher, Structures Laboratory, Department of Civil Engineering,
University of Patras, Greece
ikarakasis@upatras.gr
3 Professor, Structures Laboratory, Department of Civil Engineering, University of Patras, Greece
fardis@upatras.gr
sbousias@upatras.gr
Abstract. Progressive collapse due to loss of key load-bearing elements can be prevented if the structural system is characterized by robustness and redundancy. Field evidence shows that, despite contributing to the increase in the vertical load, non-load-bearing masonry infilling also increases the resistance to vertical loads as in the case of complete loss of one or more columns due to earthquake or blast. This anti-progressive collapse scheme may play a decisive role against building collapse and is experimentally investigated in the present paper. A two-storey, 2-by-3 bay reinforced concrete buiding was constructed at 1:1.25 scale; the ground storey was left open and masonry infills were added along the perimeter of the upper floor, with openings of different dimensions at specific bays. Extensive instrumentation was installed throughout the structure. Additional floor loads simulated the weight of finishings and the quasi-permanent live loads, as well as the effect of scale on density. The building was tested for loss of an intermediate exterior, a corner, or a central column (in that sequence) by a purpose-built, instant-release mechanism. The tests yielded that removal of an internal column (bearing the largest axial force among the three columns removed) had the most marked impact on the rest of the building, albeit that impact being minor: no visible cracking of the infills or the concrete, let alone yielding of the reinforcement. In a final testing phase the additional load was increased to a weight-equivalent of one more storey and the intermediate outer column was removed, after knocking down the infills of the entire side above. Hairline cracks which appeared in the parapets and the concrete were closed after removing the additional load.
Keywords: Progressive collapse, accidental action, loss of column, masonry infills.
