Enhanced seismic resistance of welded steel grid frame with interstorey beams

Experimental and analytical investigations of steel frames have mainly focused on connection design, with little attentive scrutinization paid to their ductility design. This paper presents a steel grid frame featuring the special interstorey beams that provides the same advantages as the ordinary steel frames, but with improved lateral stiffness and seismic performance. Accordingly, two comparative steel frames with the same steel consumption were constructed at a scale of 1:3, one of which consisted of the steel grid frame and the other of which was a standard steel frame. Two sets of frames were pseudo-statically tested under reversal load, their strain sequences and failure modes were investigated, and seismic indicators were compared including hysteresis curves, load-bearing capability, ductility coefficient, and energy dissipation. The experimental results indicate that the failure mode of the steel grid frame was mainly dominated by the interstorey beams. The interstorey beam is the primary component for energy dissipation and effectively realizes the seismic design concept of a strong column and a weak beam, thus achieving the goal of frame protection. The steel grid frame shows an increase of 3.54 % in the initial stiffness and an increase of 18.51 % in the ultimate load-bearing capacity compared to a standard steel frame. Its superior seismic performance is also demonstrated by an increase in the ductility coefficient from 30.5 % to 57.8 %. Consequently, the seismic performance of the weak-axis connected steel grid frame is superior to that of the strong-axis connected conventional steel frame, which is well-behaved in the numerical frame models.