Research On Flexural Resistance Of New Rectangular Hollow Flange I-Beam

To improve the weak global stability of conventional I-girder, a new rectangular hollow flange beam(NRHFB) is presented in this study. In the NRHFB, a cold formed retangular tube is used as the top flange and flat steel plate is still used as the bottom flange and the web. Compared to conventional I-girder, the hollow flange has a closed section, which can improve the torsional stiffness of the beam. The cross section of the hollow flange has a wide side size to increase the inert moment. Due to a large torsional stiffness of the hollow flange, the resistance to global instability of an NRHFB is greatly improved, and its failure mode is flexural strength failure. As the plastic deformation of a beam due to flexural strength failure is very large, a remarkable failure symbol can be observed, and more energy can be absorbed by the new beam. Compared to the present hollow flange beam(LHFB) investigated by researchers in the world, the web of the NRHFB is inserted directly into the hollow flange, and it can sustain concentrated force located locally at the beam. Such sopport can reduce local deformation of the holllow flange as well as resist the local buckling of the thin-walled tube.The following work has been studied:(1) Experimental study on flexural behavior of NRHFB under concentrated load at the mid-span. Through the tested load-strain curves, load-displacement curves and the observed failure mode, the flexural performance of the new beam is analyzed.(2) Finite element software ABAQUS is used to simulate and analyze the NRHFBs. The simulated results are evaluated through comparison with experimental results.(3) Finite element models of conventional hollow flange beam(LHFB), the presented NRHFB and the conventional I-girder are built. The failure mode, the load carrying capacity and the resistance to deformation of the three types of beams are compared, and local deformation of LHFB and NRHFB is also compared.(4) Parametric study has been conducted to investigate the flexural behavior of LHFB and NRHFB. The effect of the loading type(concentrated load at the mid-span, uniformly distributely load and pure bending moment) and the span(3m, 4m, 6m and 8m) on the flexural behavior of NRHFB and LHFB is analyzed. The advantages of the presented NRHFB are assessed through the discussion on the ultimate strength and on the local deformation of the two beams with different parameters respectively.