Comparative experimental investigation on steel staggered-truss constructed with different joints in fire

A total of three fire tests have been conducted to compare the mechanical performance of the steel staggered-truss (SST) exposed to pool fire constructed with welded joints and gusset plate connections. The data of temperatures and deflections of typical members were recorded during the three tests. The experimental results showed that the performance of the connections had a significant influence on the mechanical behavior of the structure under elevated temperatures. The truss constructed with gusset plate connections (TRG) possesses better fire performance than the truss adapted with welded joints (TRW) because the gusset plate connection has better resistance capacity in fire than the welded joint does. Particularly, a chain of destruction might be aroused in the TRW due to local buckling and joint fracture, and then the progressive collapse of the whole structure might be induced. However, better coordination of the truss members is shown in the TRG because the gusset plate connections possess better hinged performance in fire, and the instantaneous damage of the structure was not induced; though the failure of some specific members was observed. The difference in the manifestation of the local buckling between the TRW and TRG was also found through the tests. That is, in-plane local buckling was observed in the TRW, while either in-plane or out-plane local buckling might be induced in the TRG.

► Three fire tests of steel staggered-truss (SST) system were conducted.
► Welded joint and gusset plate connection are adopted respectively.
► The data of temperatures and displacements of typical members were obtained.
► The influence of two types of joint on the fire performance of SST was compared.
► The different buckling manifestation was discussed.