It is founded that the size of curvature difference envelop curve can detect that of pre-stress losses.

发现可以通过模态曲率差的包络图面积，较好的反映出预应力损失程度的大小。

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HHT has not been put forward for long time, so it contains some theoretical problems, such as envelop and mean curve fit, boundary effect, modes mix and so on.

HHT刚提出不久，其理论本身还存在不少问题，如包络线和均值曲线的拟合、边界效应和模态混叠等问题。

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This model contains a series of governing variables to envelop the complicated hysteretic curve of steel braces and the governing variables can be calibrated by available test results.

该模型通过一系列控制参数来包络钢支撑复杂的滞回曲线，并根据已有的同类型支撑试验结果标定控制参数。

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