To estimate the extreme load effects on a bridge towerbasement system under the joint actions of wind and wave precisely, an improved approach based on statistical extrapolation aiming to calculate the extreme load effects under the joint actions of several environmental variables was proposed. In this approach, the distribution function of peak load effects was extrapolated by the joint distribution property of environmental variables and dynamic properties of structures, and the extreme load effect was taken as the peak load effect associated with a given exceedance probability. The extreme load effects on a bridge towerbasement system due to the joint actions of wind and wave were computed by the proposed method, and the coupling effects of wind and wave were studied numerically. It is demonstrated that the proposed method is effective and adequate to predict the extreme load effects on structures under the joint stochastic actions of wind and wave for structural design purpose．
TU Zhi bin, HUANG Ming feng,LOU Wen juan. Extreme load effects on bridge towerbasement system due to joint actions of wind and wave. JOURNAL OF ZHEJIANG UNIVERSITY (ENGINEERING SCIENCE), 2016, 50(5): 813-821.
［1］ DNYOSJ101. Design of offshore wind turbine structure ［S］\[S.l\]： DET NORSKE VERITAS, 2010: 9-22．
［2］ IEC 614001 Ed.3. Wind turbinesPart 1: Design requirements ［S］. Intl. Electrotechnical Commission: Geneva Switzerland, 2005: 19-32．
［3］ IEC 614003. Wind turbinesPart 3: Design requirements for offshore wind turbines ［S］. Intl. Electrotechnical Commission: TC88 WG3 Committee Draft, 2005: 18-21．
［4］ 李锋. 海洋工程双变量环境条件设计参数估计［D］. 青岛：中国海洋大学, 2005:17-40．
LI Feng. Design parameter estimation of bivariate environmental conditions in ocean engineering ［D］. Qingdao: Ocean University of China, 2005: 17-40．
［5］ 董胜, 翟金金, 陶山山. 基于Archimedean Copula函数的风浪联合统计分析［J］. 中国海洋大学学报, 2014, 44(10): 134-141．
DONG Sheng, ZHAI Jinjin, TAO Shanshan. The joint statistical analysis of wind and wave based on Archimedean Copula functions ［J］. Periodical of Ocean University of China, 2014, 44(10): 134-141．
［6］ 周道成, 段忠东. 耿贝尔逻辑模型在极值风速和有效波高联合概率分布中的应用［J］. 海洋工程, 2003, 21(2): 45-51．
ZHOU Daocheng, DUAN Zhongdong. The Gumbellogistic model for joint probability distribution of extremevalue wind speeds and effective wave heights ［J］. The Ocean Engineering, 2003, 21(2): 45-51．
［7］ LONGO S. Windgenerated water waves in a wind tunnel: Free surface statistics, wind friction and mean air flow properties ［J］. Coastal Engineering, 2012, 61: 27-41．
［8］LONGO S, LIANG D, CHIAPPONI L. Turbulent flow structure in experimental laboratory windgenerated gravity waves ［J］. Coastal Engineering, 2012, 64: 1-15．
［9］ MYRHAUG D, ONG M C. Effect of wave age on wind gust spectra over wind waves［J］. Journal of Offshore Mechanics and Arctic Engineering, 2009, 131(3): 034501．
［10］ ANDERSEN O J, LVSETH J. Stability modifications of the Frya wind spectrum ［J］. Journal of Wind Engineering and Industrial Aerodynamics, 2010, 98(4/5): 236-242．
［11］ 欧进萍, 肖仪清, 段忠东, 等. 基于风浪联合概率模型的海洋平台结构系统可靠度分析［J］. 海洋工程, 2003, 21(4): 17．
OU Jinping, XIAO Yiqing, DUAN Zhongdong, et al. Structual system reliability analysis for offshore platforms based on the joint probabilistic model of wind and wave［J］. The Ocean Engineering, 2003, 21(4): 17．
［12］ YUE S. The Gumbel logistic model for representing a multivariate storm event ［J］. Advance in Water Resources, 2001, 24(2): 179-185．
［13］ 刘伟. 基于最大熵分布的海洋平台环境条件联合重现值推算［D］. 青岛: 中国海洋大学, 2011: 64-87．
LIU Wei. Joint return values calculation of environmental conditions with maximum entropy distribution for offshore platform design ［D］. Qingdao: Ocean University of China, 2011:64-87．
［14］ 韦艳华, 张世英. Copula理论及其在金融分析上的应用［M］. 北京:清华大学出版社, 2008: 140．
［15］ GENES C, FAVRE A C.Everything you wanted to know about Copula Modeling but were afraid to ask ［J］. Journal of Hydrologic Engineering, 2007, 12(4):347-368．
［16］ WIST H T, MYRHAUG D, RUE H. Statistical properties of successive wave heights ans successive wave periods ［J］. Applied Ocean Research, 2005, 26(3/4): 114-136．
［17］ SILVAGONZLEZ F, HEREDIAZAVONI E, MONTESITURRIZAGA R. Development of environmental contours using Nataf distribution model ［J］. Ocean Engineering, 2013, 58:27-34．
［18］ 陶山山. 多维最大熵模型及其在海岸及海洋工程中的应用［D］. 青岛:中国海洋大学, 2013: 76-113．
TAO Shanshan. Study on multivariate maximum entropy models and their application in coastal and ocean engineering ［D］. Qingdao: Ocean University of China, 2013: 76-113．
［19］ 陈子燊. 波高与风速联合概率分布研究［J］. 海洋通报, 2011, 30(2): 158-163．
CHEN Zishen. Study on joint probability distribution of wave height and wind velocity［J］. Marine Science Bulletin, 2011, 30(2): 158-163．
［20］ YANG X C, ZHANG Q H. Joint probability distribution of winds and waves from wave simulation of 20 years (19892008) in Bohai Bay ［J］. Water Science and Engineering, 2013, 6(3): 296-307．
［21］ ZHANG Y, BEER M, QUEK S T. Longterm performance assessment and design of offshore structures ［J］. Computers and Structures, 2015, 154:101-115．
［22］ GHORBEL A, TRABELSI A. Energy portfolio risk management using timevarying extreme value Copula methods［J］. Economic Modelling, 2014, 38: 470-485．
［23］ TRIVEDI P K, ZIMMER D M. Copula modeling: an introduction for practitioners. Foundations and Trends in Econometrics ［M］. Boston: Now Publishers, 2007: 53-70．
［24］ SUNDARESAN A, VARSHNEY P K. Location estimation of a random signal source based on correlated sensor observations［J］. Signal Processing, IEEE Transactions on, 2011, 59(2): 787-799．
［25］ AGARWAL P, MANUEL L. Extreme loads for an offshore wind turbine using statistical extrapolation from limited field data［J］. Wind Energy, 2008, 11(6): 673-684．
［26］ AGARWAL P, MANUEL L. Simulation of offshore wind turbine response for longterm extreme load prediction［J］. Engineering structures, 2009, 31(10): 2236-2246．
［27］ RAGAN P, MANUEL L. Statistical extrapolation methods for estimating wind turbine extreme loads［J］. Journal of Solar Energy Engineering, 2008, 130(3): 119．
［28］ TURKSTRA C J, MADSEN H O. Load combinations in condified structural design ［J］. Journal of the Structural Division, 1980, 106(12): 2527-2543．
［29］ YEO, D. Multiple PointsInTime Estimation of Peak Wind Effects on Structures ［J］. Journal of Structural Engineering, 2013, 139(3): 462-471．
［30］ 黄本才,汪丛军. 结构抗风分析原理及应用 ［M］. 第2版,上海:同济大学出版社, 2008: 49-51．
［31］ 王树青, 梁丙臣. 海洋工程波浪力学［M］. 青岛: 中国海洋大学出版社, 2013: 175-184．
［32］ DNVRPC205. Environmental conditions and environmental loads Recommended Practice ［S］. Norway: DNV, 2012．
