Forensic analysis taken after the collapse of a historical bell

Abstract

This paper describes the analysis performed after the collapse of the historical EL JAUME Bell in the Cathedral of Valencia´s Micalet Bell Tower in Spain (Fig.1). When the bells were being rung during the celebration on Christmas Day 2014, a sudden collapse took place fortunately without any casualties. After several visits to the bell tower, a forensic study was carried out to determine the causes that had originated the collapse of this historical bell, which dates back to 1429. A fractographic and metallographic analysis of the steel shaft was initially carried out. This study allowed us to know the characteristics and mechanical properties. In a second phase, a fatigue damage analysis was carried out. The remaining fatigue life was estimated from the Whöler SN curves for elements subjected to rotational bending. Once this analysis was performed, it was concluded that the bell collapse was caused by fatigue damage in steel shaft, which theoretically should have been reached between 300000 and 400000 cycles. Specifically, damage propagation occurred due to an incorrect design of the steel shaft that caused a cross section with high stress concentration. Finally, the paper shows the remedial measures proposed in all the bells of the Micalet bell tower, whose steel shafts were designed under the same criteria and therefore, there was uncertainty about their remaining fatigue life.