Results 1 - 3 of 3
Results 1 - 3 of 3. Search took: 0.015 seconds
|Sort by: date | relevance|
[en] In recent decades, the seismic assessment of existing buildings has developed significantly from traditional objectives that focused on ensuring life safety of the building. The economic impact of the 1994 Northridge earthquake in the US due to the extensive damage suffered by buildings, in addition to the overall disruption, highlighted the need for a paradigm shift in the way in which the performance of buildings ought to be defined. This paper considers the assessment of existing Italian reinforced concrete (RC) frame buildings with masonry infill, which were typically gravity load designed (GLD) prior to the introduction of seismic design provisions in the 1970s. The assessment of GLD RC frames with masonry infill is discussed within a setting similar to that of the FEMA P58 guidelines that aim to provide practising engineers with the tools and procedures; both advanced and simplified, to quantify the performance of existing buildings in a more meaningful way that can be easily conveyed to decision makers. In this study, extensive numerical analysis was carried out on a variety of case study buildings to quantify and benchmark the performance; both in terms of expected demand and overall collapse capacity, where the impact of incorporating the potential shear failure in column members was shown to result in a reduction of up to 10% of the median collapse intensity due to the interaction with the masonry infill. Furthermore, loss estimation studies were carried out on these case study buildings to not only quantify the expected losses but also investigate ways in which shrewd retrofitting of both structural and non-structural elements can have maximum impact on the overall performance. On the contrary, it was shown that by adopting structural retrofitting schemes involving strengthening and/or stiffening of the structure in compliance with NTC 2008 requirements in these situations may actually lead to a worsening of the building performance defined in terms of expected annual loss. Overall, this paper provides insight into the probabilistic seismic assessment and retrofit considerations for existing GLD RC frames in Italy.
[en] Highlights: • The quality of air and fresh water across much of the U.S. has improved markedly. • Air pollution decreased in response to policy informed by monitoring and research. • Pollution reductions have included lead, tropospheric ozone, haze, acids, and mercury. • Pollution reductions provide environmental, social, and economic benefits. • Long-term data are critical to fact-based decision-making in setting policy. - Abstract: We summarize past examples of the use of science to document the effectiveness of policy in air quality management. Our goal is to inform public discourse amidst attempts to negate the relevance and value of scientific data and fact-based analysis in favor of partisan opinion and ideology. Although air quality is fundamental to environmental and human health, air pollution has degraded natural systems and reduced economic and cultural benefits and services. The quality of air and fresh water across much of the United States vastly improved in recent decades in response to the Clean Air and Clean Water Acts and other rules and policies. We point to recently observed decreases in air pollution and its effects attributable to policy that have been informed by environmental monitoring and research. Examples include decreased environmental lead contamination due to the elimination of tetraethyl lead from gasoline, decreases in tropospheric ozone, improved visibility from reduced airborne particulate matter, declines in atmospheric sulfur and nitrogen deposition that acidify the environment and declines in atmospheric mercury and subsequent bioaccumulation of toxic methyl mercury. Pollutant reductions have provided environmental, social, and economic benefits, highlighting the urgency to apply these lessons to address current critical environmental issues such as emissions of greenhouse gases. These examples underscore the important role of data from long-term research and monitoring as part of fact-based decision-making in environmental policy.
[en] Concern regarding the impacts of continued nitrogen and sulfur deposition on ecosystem health has prompted the development of critical acid load assessments for forest soils. A critical acid load is a quantitative estimate of exposure to one or more pollutants at or above which harmful acidification-related effects on sensitive elements of the environment occur. A pollutant load in excess of a critical acid load is termed exceedance. This study combined a simple mass balance equation with national-scale databases to estimate critical acid load and exceedance for forest soils at a 1-km2 spatial resolution across the conterminous US. This study estimated that about 15% of US forest soils are in exceedance of their critical acid load by more than 250 eq ha-1 yr-1, including much of New England and West Virginia. Very few areas of exceedance were predicted in the western US. - This simple mass balance equation estimated that 17% of US forest soils exceed their critical acid load by more than 250 eq ha-1 yr-1, and these areas are predominantly located in the northeastern US