Natural Hazards - The central USA has experienced an increase in the frequency and magnitude of human-induced earthquakes. The earthquakes are caused by the deep-well injection of water produced... 相似文献
An understanding of the fracture mechanics of geomaterials is important for the solution of many problems in geomechanics. One of the most important material properties involved in fracture mechanics is the fracture toughness, KIc. The short-rod test configuration proposed by Barker1 has significant potential for becoming a standard test for fracture toughness determination in geomechanics. The purpose of this brief is to examine the application potential of the short-rod test for geomechanics problems. 相似文献
This study assesses the wind performance of various housing typologies representing informal construction practices in Puerto Rico to suggest modifications to enhance housing resilience in hurricanes. Based on fieldwork and interviews, the study defined four base housing typologies and possible variations in design and construction details. Each house was assessed using performance-based static wind analysis of potentially critical components. The results show that the initial governing failure mode in all base house typologies considered is roof panel loss due to tear-through at the fasteners, with subsequent governing failures being panel loss due to failures at the purlin-to-truss connections and failures of the truss-to-wall connections. In-plane wall failures and masonry uplift failures were both found to occur at much higher wind speeds than roof failures. To improve the hurricane performance, several feasible modifications are suggested, including installing hurricane straps at both the truss-to-wall and the purlin-to-truss connections, as well as improving the panel-fastener interface. In the construction of new roofs, this study found that using reduced spacing between roof members, hip roofs instead of gable roofs, and higher roof slopes leads to improved performance. These recommendations can make houses built through informal construction processes safer and more resilient to hurricanes as a form of climate adaptation.
Activities related to oil and gas production, especially deep disposal of wastewater, have led to sequences of induced earthquakes in the central United States. This study aims to quantify damage to and seismic losses for light-frame wood buildings when subjected to sequences of induced, small to moderate magnitude, events. To conduct this investigation, one- and two-story multifamily wood frame buildings are designed, and their seismic response dynamically simulated using three-dimensional nonlinear models, subjected to ground motion sequences recorded in induced events. Damage is quantified through seismic losses, which are estimated using the FEMA P-58 methodology. Results show that at levels of shaking experienced in recent earthquakes, minor damage, consisting of cracking of interior finishes and nonstructural damage to plumbing and heating, ventilation, and air conditioning systems, is expected, which is consistent with observed damage in these events. The study also examines how expected losses and building fragility will accumulate and/or change over a sequence of earthquakes. Results indicate that damage quantified in terms of absorbed hysteretic energy tended to accumulate over the sequences; this damage corresponds to elongation or widening of cracks. However, fragility is not significantly altered by damage in a preceding event, meaning structures are not becoming more vulnerable due to existing damage. In addition, sequences of events do not change losses if the building is only repaired once at the end of the sequence, as the worsening of damage does not alter repair actions. If repairs are conducted after each event, though, total seismic losses can increase greatly from the sequence. 相似文献
The anomalous weather patterns observed world-wide associated with El Niño are often accompanied by changes in local sea levels. Sea level anomalies are transmitted through various oceanic and atmospheric pathways and data suggest that this effect is currently on the order of tens of centimetres in some areas both within and outside of the equatorial Pacific. Positive sea level anomalies either generated or enhanced by El Niño have been linked to powerful storm waves and coastal flooding. 相似文献