基于CNN-BiLSTM-Attention混合神经网络的结构非线性模型修正

STRUCTURAL NONLINEAR MODEL UPDATING BASED ON CNN-BILSTM-ATTENTION HYBRID NEURAL NETWORK

  • 摘要: 针对结构动力响应数据的非线性和时序性特点,该文基于注意力机制(attention mechanism, AM)提出了一种卷积神经网络(convolutional neural network, CNN)和双向长短期记忆网络(bidirectional long short-term memory, BiLSTM)相结合的结构非线性模型修正方法。首先,在CNN层中利用一维卷积核进行数据非线性局部特征提取,并通过最大池化操作压缩重要特征信息;接着,BiLSTM层将CNN层传递的降维特征信息分别利用前向和后向链式连接的LSTM单元进行时序特征提取,并引入AM机制,对BiLSTM隐藏层所提取到的时间信息通过加权的方式进行重要程度区分,挖掘响应数据深层次的时序特征;最后,将Attention层的输出作为全连接层的输入,预测计算得到修正后结构非线性模型参数。通过对地震荷载作用下的桥塔模型进行数值模拟分析,并对实际缩尺桥塔结构进行振动台试验以验证所提方法的准确性。数值模拟和实验结果表明,该文所提混合神经网络修正方法适用于高维空间参数的非线性模型,相比于传统神经网络方法具有更强的鲁棒性和网络泛化能力。

     

    Abstract: In view of the nonlinear and time-series characteristics of structural dynamic response data, a convolutional neural network (CNN) and a bidirectional long short-term memory (BiLSTM) combined structural nonlinear model updating method are proposed based on attention mechanism (AM). Firstly, the one-dimensional convolutional layer is employed in CNN for the nonlinear local feature extraction, and subsequently compressed by the maximum pooling operation. Then, time-series characteristics of the reduced-dimensional information conveyed by a CNN layer is extracted by forward and backward chain-connected LSTM units in a BiLSTM layer. Meanwhile, the AM mechanism is introduced to distinguish the importance degree of time information extracted from the BiLSTM hidden layer by weightings and mining deep time-series characteristics of dynamic response data. Finally, the outputs of the attention layer are adopted as the inputs of the fully-connection layer to obtain the final model prediction results. Numerical simulation on a bridge tower structure subjected to seismic loading is conducted. Furthermore, the shake table test of an actual scaled bridge tower is applied to verify the accuracy of the method proposed. Both numerical and experimental results have shown that the hybrid neural network method proposed is applicable to update the nonlinear model with high-dimensional spatial parameters. Meanwhile, comparing with conventional neural network approaches, this methodology exhibits stronger robustness and network generalization ability.

     

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