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1.
山东Ⅱ、Ⅲ类场地地震动峰值加速度放大效应分析 总被引：1，自引：0，他引：1
利用山东地区实测的Ⅱ类场地358个钻孔和Ⅲ类场地140个钻孔的地震动峰值加速度,计算了各个钻孔不同超越概率的土层地震动峰值加速度的放大系数ks,结果表明:(1)同类场地土层放大系数ks值总体符合正态分布,既有相对集中性,也有离散性;(2)随着基岩面输入地震动强度的增大,ks值降低,且Ⅲ类场地ks值降低较Ⅱ类的更为明显;(3)Ⅱ类场地随着基岩输入面埋深的增加,ks值呈增加趋势,约达20m深后基本趋于稳定,而Ⅲ类场地基岩输入面埋深的增加对ks值的影响不甚显著;(4)Ⅱ类场地50年超越概率10％的平均ks值(1.47)略高于《中国地震动参数区划图》使用的全国平均ks值.本文尝试讨论了山东地区Ⅱ、Ⅲ类场地不同强度基岩峰值加速度输入的ks调整值. 相似文献
2.
The distribution of nonlinear wave crests is examined on the basis of a theoretical probability density previously given elsewhere (J. Eng. Mech. 120 (1994) 1009). Certain errors contained in the original theoretical density are corrected, and the corresponding exceedance distribution is derived. The resulting theoretical forms of the probability density and exceedance distribution are then slightly simplified and compared with nonlinear wave data gathered under hurricane conditions. The results indicate that the proposed theoretical forms describe the observed distributions of large wave crests better than the Rayleigh law. However, the quantitative accuracy of the predictions is somewhat poor, as is typical of approximate theories based on Gram–Charlier-type expansions. 相似文献
3.
A statistical model is developed to predict wave overtopping volume and rate of extreme waves on a fixed deck. The probability density function for the volume and rate of overtopping water are formulated based on the truncated Weibull distribution with the assumption of local sinusoidal profile for small amplitude waves. Sensitivity to the wave nonlinearity parameter and deck clearance is discussed. The statistical model is compared to laboratory data of the instantaneous free surface elevation measured in front of a fixed deck, and overtopping volume and overtopping rate measured at the leading edge of the deck. The statistical theory compared well with the measured exceedance probability seaward of the deck. The model prediction of the exceedance probability of deck overtopping gave qualitatively good agreement for large overtopping values. 相似文献
4.
A probabilistic framework is presented to select the design significant wave height and design transverse rotation for typical barges used in the Gulf of Mexico for marine transportation of structural elements and/or systems. The selection of design transverse rotation is based on optimization procedure that trade-off between the performance of the barge subjected to a meteorological-oceanographic (metocean) hazard along the route and losses by structural damage. For this purpose probabilistic models to estimate the metocean hazard for marine transportation are shown. Afterwards, the design rotation is linked to the design of significant wave height and to the return period associated with such wave conditions. The formulation is applied to an offshore transportation route in the Gulf of Mexico. 相似文献
5.
Three and four parameter distributions of events and intervals based on the Kummer and Tricomi functions are shown to be
statistically tractable. The Kummer distributions cover events less as well as more clustered than the Poisson while the Tricomi
distributions have two and three parameter negative binomials as special cases. This flexibility and the moment relations
between the parameters make them attractive in cases where the Poisson distribution proves inadequate. 相似文献
6.
攀西地区不同风险水平下基岩地震动参数之间的关系 总被引：4，自引：0，他引：4
基于攀西地区基岩有效峰值加速度（EPA）区划图，本文统计得出50年超越概率63％，5％，3％，2％，1％下EPA与50年超越概率10％下EPA的比值分别为0.302,1.30,1.55,1.76,2.14,若以攀西地区地震动参数区划图作为抗震设防标准，同时仍按照89建筑规范中的有关规定进行地震作用计算，所考虑的地震作用是偏于保守，安全的，进一步研究比值A10/A63,发现其主要影响因素依次为地震动衰减关系，地震区带与潜在震溱区划分方案，地震活动性参数。本文研究成果将有助于地震参数区划图的推广和应用。 相似文献
7.
Influence of weak trends on exceedance probability 总被引：1，自引：0，他引：1
Studying the hypothetical case of a trend superimposed on a random stationary variable, we highlight the strong influence
of possible non-stationarities on exceedance probability. After a general outline, the subject is analytically developed using
the Gumbel distribution, emphasizing the quick increase of the exceedance probability over time in the presence of weak rising
trends, and its sensitive underestimation where the non-stationarity goes unnoticed or is considered negligible. Finally the
work is applied to hydrological series of rainfall and river flow.
Received: March 27, 1997 相似文献
8.
Detailed laboratory measurements were made of the instantaneous free surface elevation in front of a fixed deck and the instantaneous free surface elevation, velocity, and overtopping rate at the leading edge of the deck. The study showed that the exceedance probabilities for the normalized maximum instantaneous overtopping rate and the normalized overtopping volume were predicted by a simple exponential curve. The measured exceedance probability seaward of the deck compared well with the nonlinear theory of Kriebel and Dawson (Kriebel D.L., Dawson T.H., 1993. Nonlinearity in wave crest statistics. In: Proceedings Ocean Wave Measurement and Analysis. American Society of Civil Engineers, pp. 61–75). Conditional sampling of the crest heights seaward of the deck gave a normalized probability distribution similar to that of the maximum water level measured on the deck for each overtopping event. However, the values used to normalize each distribution were not the same. 相似文献
9.
土的动剪切模量比和阻尼比是土层地震反应分析、工程场地地震安全性评价和地震小区划工作中的必备参数,但其不确定性显著,对地震动和抗震设计影响很大。本文以我国常规土类动剪切模量比和阻尼比与剪应变非线性关系试验为基础,研究考虑这两个动力参数变异性下其超越概率的计算方法。方法包括了试验数据的整理、超越概率的计算以及两个动力参数和超越概率关系模拟等几个步骤,最后给出了我国常规土类动剪切模量比和阻尼比超越概率的计算公式,为我国基于概率和可靠度思想的工程地震安全风险评估提供了一定基础。 相似文献
10.
This paper presents a procedure to calculate the design pressure distributions on the hull of a wave energy converter (WEC). Design pressures are the maximum pressure values that the device is expected to experience during its operational life time. The procedure is applied to the prototype under development by Martifer Energy (FLOW—Future Life in Ocean Waves).A boundary integral method is used to solve the hydrodynamic problem. The hydrodynamic pressures are combined with the hydrostatic ones and the internal pressures of the large ballast tanks. The first step consists of validating the numerical results of motions by comparison with measured experimental data obtained with a scaled model of the WEC. The numerical model is tuned by adjusting the damping of the device rotational motions and the equivalent damping and stiffness of the power take-off system. The pressure distributions are calculated for all irregular sea states representative of the Portuguese Pilot Zone where the prototype will be installed and a long term distribution method is used to calculate the expected maximum pressures on the hull corresponding to the 100-year return period. 相似文献