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Wind turbines are conceived, designed and operated to interact with the environment, including through extreme events. However, engineering malpractices combined with human or mechanical errors and defects of constituent members and materials, still result in hundreds of structural collapse cases annually. It seems, therefore, necessary to reflect on factual wind turbine performance against the target performance. The present paper summarises the most severe tubular wind tower collapse incidents recorded over the past four decades, provides an account of the damage and discusses the respective potential causes. The investigation indicates that, although accidental load induced by typhoons and storms is the most usual reason of failure, fatal events concentrate at either early or late stage of the designed service life. Unexpected load conditions seemed to derive from defective blade positioning or braking, which in turn over-stress areas of transition such as joints and openings. However, a critical examination of design standards suggests that, in general, wind turbine towers as designed and built nowadays are stable and reliable. Hence, the chain relationship determined by the design, manufacturing, construction, operation and maintenance, needs enhancement and further cohesion, at the time that our understanding of and adaptation to extreme events continues to develop.

The need for embedding sustainability in construction development contributed to the introduction of Building information Modelling (BIM) to be adopted into the Life Cycle Cost (LCC) process. Through BIM, project information used during design can be shared to estimate the project’s end of life costs. LCC enables to assess the overall cost of an asset (building) through its life cycle via functionalities including the original investment costs, maintenance expenses, operating expenses, and the remaining value of the asset at the end of its life. The objective of this paper is to discuss the merging of BIM into LCC through four prevalent aspects; methodology, design software used, benefits, and challenges. A total of 20 studies were reviewed upon filtering process using PRISMA method. These studies discussed at least one of the aspects mentioned and contributed to the information regarding BIM and LCC. This paper thus aims to expanding studies on BIM adoption on LCC through the collected information sourced from peer-reviewed publications.

Strength reduction factors (SRFs) are typically estimated for seismic events ignoring the influence of wind. However, considering that strong earthquakes are commonly followed by a number of moderate to strong aftershocks and that wind is constantly flowing, often with low to medium intensity but occasionally reaching high speeds, then the assumption of using only earthquake ground records to determine SRFs seems questionable. In this paper it is shown that the combined action of strong winds and earthquakes, however low its probability of occurrence, would considerably increase the ductility demand of buildings and cause a decrease in SRFs calculated by ignoring wind. The paper examines the non-linear performance of single-degree-of-freedom systems subject to various levels of winds and earthquake load and deals with the estimation of SRFs associated with those multi-hazard scenarios.

This research examines the effect of plan irregularities on the progressive collapse of four steel structures located in regions with different seismic activity. The plans of the first and second structure are irregular, whilst those of the third and fourth structures are regular. The collapse patterns of the four buildings are examined and compared under seven loading scenarios using non-linear dynamic and static analyses. In the non-linear dynamic analyses, node displacements above the removed columns and the additional force on the columns adjacent to them are discussed. Furthermore, the strength and capacities of the columns are compared to determine their susceptibility to collapse. In the non-linear static analyses, the pushdown curve and yield load factor of the structures are obtained after column removal. The results indicate that an irregular structure designed in site class C seismic zone, collapses in most of the column-removal scenarios. Moreover, when comparing regular and irregular ...

This investigation deals with numerical solution of complex aerodynamic interactions induced by a high-speed train (HST) entering and passing through tunnels with a closely adjacent gap and without in between. We present evidences that included pressure transient on the train surface and tunnel wall and comparisons between slipstreams and aerodynamic loads. The results show that two closely adjacent tunnels with a gap does not induce pressure differences on the tunnel wall, in relation to pressures otherwise observed on the single long tunnel, but slightly affects the friction component of the initial pressure rise on the train surface. In addition, the peak values of the slipstreams on the side nearest to the train inside the second tunnel are larger than those recorded when the train passed the first tunnel, suggesting that the existence of a gap between tunnels affect the airflow within the second tunnel. Peak drag coefficients for the train travelling through the first and second tunnel match while being 9.8% lower than the corresponding value observed within a single yet longer tunnel. The study highlights the differences on train aerodynamics when in transit through closely adjacent tunnels and a long tunnel to conclude that improved aerodynamic performances should be considered as the train circulates through closely adjacent tunnels as opposed to through a single passage. The study provides an aerodynamic guideline and reference for the tunnel engineering.

Traditionally, a quasi steady response concerning the aerodynamic force and moment coefficients acting on a flat plate while \'flying\' through the air has been assumed. Such an assumption has enabled the flight paths of windborne debris to be predicted and an indication of its potential damage to be inferred. In order to investigate this assumption in detail, a series of physical and numerical simulations relating to flat plates subject to autorotation has been undertaken. The physical experiments have been carried out using a novel pressure acquisition technique which provides a description of the pressure distribution on a square plate which was allowed to auto-rotate at different speeds by modifying the velocity of the incoming flow. The current work has for the first time, enabled characteristic pressure signals on the surface of an auto-rotating flat plate to be attributed to vortex shedding.

This paper describes the use of coupled Computational Fluid Dynamics (CFD) and Rigid Body Dynamics (RBD) in modelling the aerodynamic behaviour of wind-borne plate type objects. Unsteady 2D and 3D Reynolds Averaged Navier-Stokes (RANS) CFD models are used to simulate the unsteady and non-uniform flow field surrounding static, forced rotating, auto-rotating and free-flying plates. The auto-rotation phenomenon itself is strongly influenced by vortex shedding, and the realisable k-epsilon turbulence modelling approach is used, with a second order implicit time advancement scheme and equal or higher order advection schemes for the flow variables. Sequentially coupling the CFD code with a RBD solver allows a more detailed modelling of the Fluid-Structure Interaction (FSI) behaviour of the plate and how this influences plate motion. The results are compared against wind tunnel experiments on auto-rotating plates and an existing 3D analytical model.

In earthquake-prone areas, wind and earthquake loads are assumed to be statistically uncorrelated and therefore their interaction is ignored in existing design guidelines. However, the facts that strong earthquake events are commonly followed by aftershocks and that wind is constantly flowing at high speeds around wind farms increase the probability of their joint occurrence, thus making current design assumptions questionable. This investigation shows that multi-hazard scenarios magnify the strength demands of wind turbine towers designed against isolated load conditions, hence modifying their performance level. It is also shown that, under certain conditions, the probabilities associated with the joint occurrence of earthquake and low to strong wind events match or exceed those related to the original design, thus rendering wind energy infrastructure susceptible to unforeseen damage.

This paper presents the results of measurements relating to the aerodynamic forces on flat square plates which were allowed to rotate at different speeds about their horizontal axis, by modifying the velocity of the incoming flow. A 1 m square test-sheet and a 0.3 m square test-sheet were fitted with a number of pressure sensors in order to obtain information relating to the instantaneous pressure distribution acting on the test-sheet; a compact gyroscope to record the angular velocity during the rotational motion was also implemented. Previous work on autorotation has illustrated that the angular velocity varies with respect to the torque induced by the wind, the thickness and aspect ratio of the testsheet,any frictional effects present at the bearings, and the vorticity generated through the interaction between the plate and the wind flow. The current paper sets out a method based on the solution of the equation of motion of a rotating plate which enables the determination of angular velocities on autorotating elements to be predicted. This approach is then used in conjunction with the experimental data in order to evaluate the damping introduced by the frictional effects at the bearings during steady autorotation.