Impact Resistance of Steel Frames with Different Beam-Column Connections Subject to Falling-Floor Impact on Various Locations

In recent years, falling-floor impact scenarios have been studied because they may generate disproportionate collapse. A series of impact tests was carried out at Nanyang Technological University to investigate the dynamic behavior and impact resistance of steel-framed structures. Ten specimens with five types of beam-column connections - i.e., a welded unreinforced flange-bolted web connection (WUF-B), a reduced beam section connection (RBS), a fin-plate connection (FP), a reverse channel connection with flush end plate (RC-FEP), and a reverse channel connection with extended end plate (RC-EEP) - and two typical impact locations - i.e., at midspan for tensile/bending failure, and at beam end for shear failure - were tested under impact loads. Finite-element models were developed and validated against the experimental results. Numerical and experimental results indicated that the numerical model is capable of predicting the dynamic behavior of steel-framed specimens subjected to impact loading in terms of the impact force, displacement, energy absorption, and failure mode. The results showed that all specimens had greater failure displacement under midspan impact. Except Specimen FP, the specimens had greater impact force under beam-end impact. Only Specimen RC-FEP had greater energy absorption under beam-end impact than under midspan impact. Specimen RC-EEP and Specimen FP had the best and worst impact resistance, respectively, which was attributed to the greatest and lowest energy absorption at both impact locations.