Design and Research of Main Weld of Track Beam of Suspension Monorail

The track beam of suspension monorail is a combination of beam and rail structured by a thin-walled box with an opening at lower location and deck layout lower than the load-bearing structure. The main weld of flange and web on track beam is critical weld with force transferred by structure. The main weld has a complex load-carrying status which is difficult to design and check by conventional design method. Therefore, on the basis of the existing international design of track beam of suspension monorail and with reference to the Zhong Tang New Resource Sky Train Test Line Project participated by our company, the method combining finite element and theoretical calculation was used to analyze and calculated the load-carrying status of the main weld of track beam of suspension monorail. The transferring force rule of main weld seam of top/bottom flange of the track beam, main weld seam in region 1 and main weld seam along the beam length direction were studied. By the transferring force calculation of weld seam, track beam the main weld seam design of was carried out, in accordance with the Code for Design on Steel Structure of Railway Bridge (TB 10091-2017), and the weld seam strength and fatigue have been checkup. By this design method, the main weld of track beam of suspension monorail could be analyzed quantitatively, so as to avoid the main weld from being designed with overlarge size or exceed the actual need to reduce investment cost. The relevant conclusions were as follows:
1) A stress analysis for the main weld (connecting web and top/bottom flange) of the track beam of suspension monorail was comlished. The top/bottom flange and web were connected by main welds and stiffeners. The bottom flange, as the vehicle travelling surface, was subjected to the local load effect given by the wheel, thus its weld seam bore the most stress.
2) The main weld seam connecting the top/bottom flange and web were subjected to the shear effect, with the basically same shear force magnitude and the opposite shear force direction on the same section, with the calculation results concurring with the simply supported beam main weld seam capability of shear force; main weld seam of the bottom flange in the middle of the two stiffeners showed a definitely better capability of bearing vertical stress compared to the main weld seam of the top flange; bottom flange weld seam at stiffeners presented a slightly better capability of bearing vertical stress compared with top flange weld seam at stiffeners, with both of which better than the bottom flange weld in the middle of the two stiffeners in terms of bearing vertical stress; M_x moment of force of bottom flange weld seam in the middle of two stiffeners was significantly larger than any other positions.
3) The vertical force in the stiffener was much larger than any other positions; the closer the longitudinal F_x to the stiffener, the quickly the F_x at stiffeners reduced under the effect of the stiffener; M_x distributed as a "V" shape, in which the least moment of force at stiffener, and it gradually increased to both sides. M_y distributed as a "M" shape.
4) The transferring force rule of F_x gradually growed from the middle of the span to the support position, F_x in Q 1 position close to hanging suspension frame position reduced because the hanging suspension frame bore the shear force exerted by the track beam. F_x in the middle of each stiffener gradually growed from the middle of the span to the support position. The vertical force Fz was mainly caused by vehicle wheel, with the basically same magnitude at each location. From the middle of the span to support location, M_x reduced at first and then increased, M_y increased gradually.