Successful development of the offshore wind energy resource depends upon the reliability of the structures that support the electricity-generating rotor-nacelle assemblies that form the core of a wind turbine system. The risk posed to offshore wind turbines (OWTs) by extreme environmental events such as Atlantic hurricanes requires a more detailed examination of post-elastic structural performa...

Lateral tower vibrations of offshore wind turbines are normally lightly damped, and large amplitude vibrations induced by wind and wave loads in this direction may significantly shorten the fatigue life of the tower. This paper proposes the modeling and control of lateral tower vibrations in offshore wind turbines using active generator torque. To implement the active control algorithm, both th...

Wind turbine reliability is an important issue for wind energy cost minimization, especially by reduction of operation and maintenance costs for critical components and by increasing wind turbine availability. To develop an optimal operation and maintenance plan for critical components, it is necessary to understand the physics of their failure and be able to develop reliability prediction mode...

In this paper, an optimum design of concrete-steel mixed frames under time-history loadings was formulated as optimization problem. The behavior a structure is different from the steel and reinforced concrete structures because vertically irregular in their mass, stiffness damping each part. Moreover, current codes available commercial software packages do not present solutions for such structu...

Title of dissertation: MULTIPLE ENERGY DISSIPATION STRATEGIES OF BASE ISOLATED STRUCTURES UNDER BLAST AND EARTHQUAKE Ruiyang Zhang, Master of Science, 2014 Dissertation directed by: Assistant Professor, Brian M. Phillips Department of Civil and Environmental Engineering Terrorist attacks have become a growing threat worldwide in recent years. Explosive devices, the weapon of choice for a majori...

The diurnal variations in soil-gas helium concentration have been monitored at depths of 0.5-2.0 m in three localities in Colorado, Wyoming, and C•lifornia.'Bar•metric p e•su TM, air temperature, wind speed, soil temperature and moisture, relative humidity, and precipitation were also measured. The helium variation below a 1-m sampling depth usually did not exceed the analytical sensitivity of ...

The term "natural disaster" is used to refer to catastrophes that arise from acts of nature such as flood, wind, drought and earthquake. However, many people have challenged this terminology as misleading. As long ago as 1976,1 Frederick Krimgold defined a disaster as an event that outstrips the capacity of a society to cope with it. This definition highlights the fact that not every natural cr...

in the current engineering practices, buildings are commonly designed for an effective lifetime of 50 years. this lifetime can increase the cost of buildings with short lifetimes and can reduce the safety level of buildings with large lifetimes. in this paper, a “service-life factor” has been defined. applying this factor into the nominal values of live, earthquake, wind, and snow loads, the ef...

This paper presented an overview on the dynamic analysis and control of the transmission tower-line system in the past forty years. The challenges and future developing trends in the dynamic analysis and mitigation of the transmission tower-line system under dynamic excitations are also put forward. It also reviews the analytical models and approaches of the transmission tower, transmission lin...