Experimental tests of partially encased beams at elevated and room temperature

This work presents the experimental tests developed on partially encased beams (PEB) at elevated temperature and room temperature. PEB were built with IPE100 steel profile. Two beam lengths were tested (2.5 and 4 m) at room, 400 and 600 ºC. Seven series were tested to compare the performance of PEB using two different stirrups shear conditions (welded -W and not welded to web - NW). The behaviour of IPE 100 PEB was also compared with IPE 100 bare steel beam at room temperature. Most of the beams attained the ultimate limit state by lateral torsional buckling (LTB), with exception for those tested at 600 ºC which collapsed by the formation of a plastic hinge (PH). The performance of each PEB was characterized based on some load events. The load value for plastic behaviour (FMpl), the load value for displacement equal to L/30 (FL/30) and the load value for the ultimate load (Fu). The bending strength of the PEB at room temperature is almost two times the bending resistance of bare steel beam. The reduction on bending resistance of PEB is not directly proportional to the increase of temperature. An increase of temperature from room to 400ºC and to 600ºC leads to a reduction of 37 % and 64% on FL/30, respectively. The ultimate load of PEB increased 85% in comparison with bare steel at room temperature. A decrease in the ultimate load of 24% and 22% was verified when temperature increased from room to 400 ºC and from 400 ºC to 600 ºC, respectively. The bending resistance of PEB without welded stirrups slightly decreased in comparison to PEB with welded stirrups