Research and Test Verification of Dynamic Characteristics of Deck V-Arch Bridge

Abstract

To solve the problem that the natural frequency of deck arch bridges would decrease rapidly when the span increases, a novel arch bridge structure named deck V-arch bridge is proposed. The V-shaped members are added between the main girders and the arch ribs to increase the stiffness of the arch bridge, thereby increasing the natural frequency of the structure. Through the timely conversion of the structural system, the first-phase dead load is carried by the arch ribs, while the second-phase dead load and live load are carried by the variable height truss with main girders as upper chords, arch ribs as lower chords, and V-shaped members as webs, with multi-point elastic constraints. The entire structure has the advantages of arch and truss. In order to verify the correctness of the research and calculation of the dynamic characteristics of the deck V-arch bridge, a test bridge with a span of 10 m is built. The first natural frequency of the vertical bending in the plane of the bridge is tested by utilzing the pulsation test. The stiffness and dynamic characteristics are calculated by utilizing the finite element software. The influence of V-shaped member stiffness on the natural frequency and that of the number of V-shaped members on the temperature stress of the structure are analyzed. The necessity of system transformation is studied. The results show that the difference between test value and calculated value of the first natural frequency of vertical bending in the plane is small. The mode shape is in good agreement with the finite element analysis. With little or no additional material, the natural frequency of the structure is significantly increased, especially the in-plane frequency. The stiffness of the V-shaped members has a reasonable setting range. When the inner angles of the triangle formed by the main girders or the arch ribs are between 45 ℃ and 60 ℃,the number of V-shaped web members is suitable. The structural stiffness of deck arch bridge with V-shaped members is greatly improved, and at the position of L/4 (L is the span of the bridge), the upward deflection generated by the static live load of the train is approximately zero. After the transformation of the structural system, the deck V-arch bridge can fully exert the superiority of the arch force.

Keywords

• deck arch bridge
• dynamic characteristics
• test
• finite element
• stiffness
• high-speed railway bridge