Relation between frequencies and impact coefficients ofcontinuous beam bridges(PDF)
长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]
- Issue:
- 2020年2期
- Page:
- 56-65
- Research Field:
- 桥梁与隧道工程
- Publishing date:
Info
- Title:
- Relation between frequencies and impact coefficients ofcontinuous beam bridges
- Author(s):
- FENG Wei1; 2; ZHU Weiqing1; HU Qiang1
- (1. School of Highway, Changan University, Xian 710064, Shaanxi, China;2. Xian Highway Research Institute, Xian 710065, Shaanxi, China)
- Keywords:
- bridge engineering; impact coefficient; theoretical analysis; continuous beam bridge; vibration mode; frequency
- PACS:
- -
- DOI:
- -
- Abstract:
- In order to clarify which order frequency was more reasonable when calculating the impact coefficients of different load effects (displacement, positive and negative bending moment and shear force) of the girder of a continuous beam bridge, the prestressed concrete (PC) continuous beam bridges with spansunite length of r×30 m (span number r=3, 4, 5, 6) were taken as the research object. By using the theoretical analysis and finite element numerical simulation simultaneously, the relation between displacement impact coefficient, positive and negative moment impact coefficient and shear impact coefficient and the first three order frequencies were studied. Firstly, the relationship between displacement impact coefficient, positive and negative moment impact coefficient, shear impact coefficient and models of each order were obtained by using dynamics and curvature modal theory. Then the beam grid method was used to establish the MIDAS Civil finite element modes of r×30 m PC continuous beam bridges. And the Fourier series were used to fit the first three order vertical bending modes obtained from the finite element analysis. Finally, the fitting mode function was substituted into the relationship between the impact coefficients of different effects and the modes of each order, so that the contributing percentages of the first three orders of vibration modes to the impact coefficients of different effects were obtained. The theoretical analysis conclusions were verified by comparing with the existing research results. The research results show that the displacement impact coefficient, positive bending moment impact coefficient, and shear impact coefficient can be calculated more reasonably according to the first order vertical bending frequency. Among the first three order vertical bending modes, the first order mode contributes 84.4% to 99.5% of the largest dynamic displacement in the midspan section, 77.2% to 98.7% of the maximum dynamic positive bending moment in the midspan section, and 84.1% to 99.1% of the maximum dynamic shear force of the bearing section. The negative moment impact coefficient is calculated more reasonably according to the second order vertical bending frequency. Among the first three order vertical bending modes, the second order mode contributes 70.0% to 98.2% of the maximum negative dynamic bending moment of the support section.
Last Update: 2020-04-09