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我们曾对坐落在加利福尼亚州的金门桥,作过广泛的实验性研究.利用外界振动数据来确定关于风和地震这两个问题的诸如有效阻尼,三维振型以及桥梁振动的有关频率的参数。本文讨论包含悬式结构的竖向,横向和纵向振动同时性测量的试验;随后一文,则叙述桥塔振动的测量。我们在加劲结构不同横截面的经过选择的点上曾作过测量:主跨上12次,边跨上6次。由于对运动敏感的一些加速度计的特殊运用和定向,又由于用加减记录的办法来鉴定和增益竖向,扭转,横向和纵向的振动模态,我们完成了良好的模态识别工作。总计起来,悬式桥跨的91个模态频率和模态位移形状,都已重新获得:20个竖向的、18个扭转的,33个横向的和20个纵向的,全都在频率范围0.0—1.5Hz之内。这些数字,包括对称和反对称振型。最后,把以前计算过的二维和三维振型与频率,跟实验结果相比较,显示它们很好地吻合。这就进一步证明实验测定的准确性和计算方法的可靠性。
We conducted a wide range of experimental studies of the Golden Gate Bridge, located in California, using external vibration data to determine parameters such as effective damping, 3D shape, and bridge vibration related frequencies for both wind and earthquake problems. This article discusses the tests for vertical, lateral and longitudinal vibrational simultaneous measurements involving suspended structures; the following article describes the measurement of the tower vibration. We measured the cross-section of stiffened structures at selected points: 12 times on the main span and 6 on the sides. Due to the special use and orientation of some accelerometers that are sensitive to motion, we have also completed good modal identification by identifying and gaining vertical, torsional, lateral and longitudinal modes of vibration with additions and subtractions of records. Taken together, 91 modal frequencies and modal displacements of the suspension bridge have been regained: 20 vertical, 18 twisted, 33 horizontal and 20 vertical, all in the frequency range of 0.0 -1.5Hz. These figures, including symmetrical and antisymmetric modes. Finally, comparing the two-dimensional and three-dimensional shapes and frequencies previously calculated with the experimental results show that they fit well. This further proves the accuracy of the experimental determination and the reliability of the calculation method.