钢-混凝土组合梁考虑界面滑移的振动模态试验研究

Experimental investigation on dynamic properties of steel-concrete composite beams considering effect of interfacial slip

为研究钢与混凝土的界面滑移效应对钢一混凝土组合梁基本动力性能的影响程度和规律，进行了5根跨度3．8133的简支钢一混凝土组合梁的静载和振动模态试验，其中4根采用抗剪栓钉，剪力连接度分别为0．6、0．7、1．0和1．4，另1根采用能提供刚性抗剪连接的开孔钢板连接件。试验结果表明：在静载作用下，随剪力连接度的提高，组合梁的界面滑移减小，抗弯刚度显著增加。竖弯模态试验中，剪力连接度小于等于1．0的3根梁，其前4阶竖向弯曲模态频率与采用开孔钢板抗剪连接件的试验梁相比均有减小，最小减幅为9．8％，最大减幅达26％；剪力连接度为1，4的梁较开孔钢板连接件的试验梁，基频减小了6．1％，第2～4阶自振频率减小幅度均在10％以上，与连接度为0．6的梁相比，其基频增大了13．2％；试验梁的模态阻尼比随着剪力连接度的增大而减小。扭转模态试验中，各阶扭转模态频率差异程度在7％以内，变化规律不明显。由此可见，钢与混凝土板的界面滑移效应对组合梁竖向弯曲自振频率的影响不容忽视，在设计计算中须予以考虑。试验结果可为工程动力分析榀供参考。

Static and dynamic experiments were conducted on five simply supported steel-concrete composite beams with the span of 3.8 m, in order to study the influence of interracial slip on dynamic properties of composite beams. Four composite beam specimens used steel studs as shear connectors with shear connection levels of 0.6, 0.7, 1.0 and 1.4. Another composite beam specimen use perforated steel slats as shear connectors, which could be considered as rigid connection. The results of static tests show that the interfacial slip of the composite beam decreases, while the bending stiffness increases significantly with the increase of the shear connection level. The vertical bending modal tests show that natural frequencies of the first four modes decrease significantly by the minimum of 9.8% and the maximum of 26% for specimens with the shear connection level 7/~〈 1.0 compared with the beam with perforated slats. The fundamental frequency of the specimen with the shear connection level 1.4 decreases by 6.1% compared with the specimen with perforated slats, while increases by 13.2% compared with the specimen with the shear connection level 0.6. The modal damping ratio of the test specimens decreases with the increase of the shear connection level. In the torsion modal tests, the difference of torsional frequency among each other is less than 7%, showing insignificant variation. The effect of interfacial slip on natural frequencies of the vertical bending mode of composite beams can not be ignored and it should be taken into account in the calculation of frequencies.