Nonlinear stiffness of narrowtall composite track beam with interlaced notches
Zhou Shuai1 Yu Peng1 Lei Jun1 Deng Lu3 Tan Zhiwen4 Shao Xudong3
1. China Construction Fifth Engineering Division Co., Ltd., Changsha 410004, China;
2. China Railway Eryuan Engineering Group Co., Ltd., Chengdu 610031, China;
3. Hunan University, Changsha 410082, China; 4. China Construction Tunnel Construction Co., Ltd., Chongqing 401320, China
Abstract：The track beam of a straddle monorail is typically a narrow-tall section. To avoid the difficulty of the positional precision control of the concrete track beam, and the noise, vibration, and weather resistance of the all-steel track beam, a model (scale of 1∶3) of the narrow-tall composite track beam with interlaced notches and three corresponding full-scale push-out test models was manufactured. To investigate the longitudinal shear and vertical bending stiffness of this type of structure, the results obtained by the theoretical formula, numerical simulation, and model test were compared. The following conclusions were drawn: ① the shear stiffness of the group nails in the dislocation notches decreased as the load increased. A large difference exists between the existing code and the test results; therefore, it is recommended that the test value is first used for the shear stiffness of this type of structure. The values obtained by the 2013 and 2015 versions of the code can be used as the upper and lower limits, respectively, and these limits can be used for structural calculation and obtaining a envelope result. The proposed formula can also be used to estimate a composite structure with an appropriate amount of rebar and welded nails. ② The equivalent vertical bending stiffness of the composite track beam is nonlinear. As the load increases, the measured equivalent stiffness is first greater and then less than the theoretical value. ③ At the same section, the steel beam and concrete slab deform incongruously along the height direction. The strain value of the concrete slab is considerably larger than that of the steel beam; therefore, it is difficult to apply the plane-section assumption.
