中、下承式钢管混凝土拱桥面内振动模态分析

采用Katayama提出的随机子空间识别法对环境脉动下八座钢管混凝土拱桥实测动力响应进行识别,与采用最大熵谱法获得的计算结果进行的比较验证了采用方法的正确性。建立了实测桥梁的有限元模型,理论模态与试验模态吻合良好,讨论了主拱跨径、截面和桥道系结构等结构参数对钢管混凝土拱桥面内振动模态特性的影响,指出了钢管混凝土拱桥面内一阶基频的统计近似公式的局限性,提出了基于Rayleigh能量法的静力计算方法,可用于预估和校核中、下承式钢管混凝土拱桥面内低阶频率。

MODAL ANALYSIS OF IN-PLANE VIBRATIONS FOR HALF-THROUGH AND THROUGH CONCRETE-FILLED STEEL TUBULAR ARCH BRIDGES

The dynamic responses under an ambient vibration for eight half-through and through concrete-filled steel tubular(CFST) arch bridges are measured.The Stochastic Subspace Identification(SSI) method presented by Katayama is used for experimental modal analyses,and the feasibility of this method is verified by comparing with the results obtained by the Maximum Entropy Method.Compared with the experimental modal analysis by SSI method,the correctness of theoretic modal analysis by the finite element method is confirmed.The influence of some parameters,such as the arch main span,cross section and deck system,is discussed on the in-plane vibration properties of CFST arch bridges.The limitation of the statistical approximate formula for the in-plane first frequencies of CFST arch bridges is pointed out,and the static method based on the Rayleigh energy method is presented,which can predict and check in-plane low frequencies of half-through and through CFST arch bridges.