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实际工程的地震危险性概率分析结果表明,即使潜在震源参数和衰减规律等输入参数完全相同,仅因震级积分步长和地震危险性曲线控制点取值不同,就可导致计算结果的显著差异。对于根据衰减规律累加潜源dxdy子源面积计算地震危险性的软件,震级积分步长建议不大于0.05级。危险性曲线控制点的范围应足够大,控制点应该适当增加密度且按对数均匀取值,以保证跨几个数量级的不同周期、不同超越概率反应谱的相对精度。上述积分步长和控制点取值的差异属于主观不确定性,在工程问题的数值计算中普遍存在。此类不确定性影响的敏感性与软件编制的技巧有关,通过减小积分步长、加密控制点可将其影响减小乃至消除。对于特定软件,改变积分步长和控制点密度,对比试算结果,不难确定兼顾计算速度和精度的合理取值。
Probabilistic seismic hazard analysis results show that even if the input parameters such as potential source parameters and attenuation law are exactly the same, the differences of calculation results can be significant only because of the difference between the magnitude of the integral points of the magnitude and the control points of the seismic hazard curve. For the software that calculates the seismic hazard according to the law of attenuation of cumulative dxdy source area, it is recommended that the magnitude integral step is not greater than 0.05. The scope of the control point of the dangerous curve should be large enough. The control point should increase the density appropriately and logarithmically to ensure the relative accuracy of different transcendental probability response spectra across different orders of magnitude. The differences between the above integral steps and the control points are subjective uncertainties, which are ubiquitous in the numerical calculation of engineering problems. The sensitivity of such uncertainties is related to the skill of software preparation. By reducing the integration step, the effect of the cryptographic control points can be reduced or even eliminated. For a specific software, change the integral step and control point density, comparing the trial results, it is not difficult to determine the reasonable value of taking into account the calculation speed and accuracy.