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Steel and Composite Structures
  Volume 35, Number 5, June10 2020, pages 641-657

Static performance of a new GFRP–metal string truss bridge subjected to unsymmetrical loads
Dongdong Zhang, Jiaxin Yuan, Qilin Zhao, Feng Li, Yifeng Gao, Ruijie Zhu and Zhiqin Zhao

    A unique lightweight string truss deployable bridge assembled by thin-walled fiber reinforced polymer (FRP) and metal profiles was designed for emergency applications. As a new structure, investigations into the static structural performance under the serviceability limit state are desired for examining the structural integrity of the developed bridge when subjected to unsymmetrical loadings characterized by combined torsion and bending. In this study, a full-scale experimental inspection was conducted on a fabricated bridge, and the combined flexural–torsional behavior was examined in terms of displacement and strains. The experimental structure showed favorable strength and rigidity performances to function as deployable bridge under unsymmetrical loading conditions and should be designed in accordance with the stiffness criterion, the same as that under symmetrical loads. In addition, a finite element model (FEM) with a simple modeling process, which considered the multi segments of the FRP members and realistic nodal stiffness of the complex unique hybrid nodal joints, was constructed and compared against experiments, demonstrating good agreement. A FEM-based numerical analysis was thereafter performed to explore the effect of the change in elastic modulus of different FRP elements on the static deformation of the bridge. The results confirmed that the change in elastic modulus of different types of FRP element members caused remarkable differences on the bending and torsional stiffness of the hybrid bridge. The global stiffness of such a unique bridge can be significantly enhanced by redesigning the critical lower string pull bars using designable FRP profiles with high elastic modulus.
Key Words
    composite structure; string structure; deployable bridge; spatial truss; extrusion-type fiber reinforced polymer (FRP); static loading test; finite element analysis (FEA)
Dongdong Zhang, Jiaxin Yuan, Feng Li,
Yifeng Gao, Ruijie Zhu and Zhiqin Zhao: College of Field Engineering, Army Engineering University of PLA,
No.1 Haifuxiang, Qinhuai District, Nanjing, 210007, P. R. China
Qilin Zhao: College of Mechanical and Power Engineering, Nanjing Tech University,
No.1 Puzhu south road, Pukou District, Nanjing, 211800, P. R. China

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