Numerical analysis on global serviceability behaviours of tall Glulam frame buildings to the Eurocodes and UK National Annexes

Glued-laminated timber (Glulam) is an innovative engineered timber product and has been widely used for constructing spatial grand timber structures and tall timber buildings due to its exceptional natural attraction, easy processing, decent fire resistance and outstanding structural performance. However, global serviceability performances of tall timber buildings constructed from Glulam products for beams, columns and bracings and CLT products for lift core and floors under wind load are not well known yet though they are crucial in structural design and global analysis. In this study, finite element software SAP2000 is used to numerically simulate the global static and dynamic serviceability behaviours of a 105 m high 30-storey tall Glulam building with CLT lift core and floors assumed in Glasgow, Scotland, UK. The maximum horizontal storey displacement due to wind is 58.5% of the design limit and the maximum global horizontal displacement is 49.7% of the limit set to the Eurocodes. The first three lowest vibrational frequencies, modes and shapes of the building are obtained, with the fundamental frequency being 33.3% smaller than the code recommended value due to its low mass and stiffness. The peak acceleration of the building due to wind is determined to the Eurocodes and ISO 10137. The results show that the global serviceability behaviours of the building satisfy the requirements of the Eurocodes and other design standards. Parametric studies on the peak accelerations of the tall Glulam building are also conducted by varying timber material properties and building masses. Increasing the timber grade for CLT members, the generalised building mass and the generalised building stiffness can all be adopted to lower the peak accelerations at the top level of the building so as to reduce the human perceptions to the wind induced vibrations with respect to the peak acceleration

A Comparative Analysis of the Use of Different Zone Models to Predict the Mass Smoke Flow for Axisymetric and Spill Plumes

Peer-reviewed article published in the Proceedings of the 9th International Symposium on Fire Safety Science, Karlsruhe, 2008.Sanderson (2007) examined the theoretical basis for and the experimentation supporting the predictive smoke zone models currently being used in fire engineering design that are cited, in nationally and internationally accepted guidance documents, to support the increasing use of performance-based building codes/regulations throughout the world. This critical examination identified anomalies: 1) between different researcher’s results, when considering the same fire environment, and 2) areas where the models used in guidance documents have limited empirical support. The variance between models was examined by the parametric variation of critical data input parameters the impact of which indicated that the most recent research produced models that predict a lower level of mass smoke flow than the earlier models. It may be suggested that the more recent research, building on previous work, produces models that can be used with a greater level of confidence however there is no robust evidence to support this. This paper illustrates the variances between the model outputs by means of a case study. Currently there is a move towards the use of Computational Fluid Dynamic modelling of fire. However, given the limited validation of these models in the area of smoke movement and the computer time and power required to run these models, there is still a place in fire engineering design for the zone model. As an increasing number of countries adopt performance building and fire codes/regulations and given the consequent need for predictive mass smoke flow models in which regulators, fire engineers and society can have confidence, it is concluded that the research supporting zone modelling of fire should be extended. This research should be robust and transparent in order to either produce models that are substantially more acceptable than those currently being used or to provide more confidence in models

Predicting 30-day mortality in patients with sepsis: an exploratory analysis of process of care and patient characteristics

Background Sepsis represents a significant public health burden, costing the NHS £2.5 billion annually, with 35% mortality in 2006. The aim of this exploratory study was to investigate risk factors predictive of 30-day mortality amongst patients with sepsis in Nottingham. Methods Data were collected prospectively from adult patients with sepsis in Nottingham University Hospitals NHS Trust as part of an on-going quality improvement project between November 2011 and March 2014. Patients admitted to critical care with the diagnosis of sepsis were included in the study. In all, 97 separate variables were investigated for their association with 30-day mortality. Variables included patient demographics, symptoms of systemic inflammatory response syndrome, organ dysfunction or tissue hypoperfusion, locations of early care, source of sepsis and time to interventions. Results A total of 455 patients were included in the study. Increased age (adjOR = 1.05 95%CI = 1.03–1.07 p < 0.001), thrombocytopenia (adjOR = 3.10 95%CI = 1.23–7.82 p = 0.016), hospital-acquired sepsis (adjOR = 3.34 95%CI = 1.78–6.27 p < 0.001), increased lactate concentration (adjOR = 1.16 95%CI = 1.06–1.27 p = 0.001), remaining hypotensive after vasopressors (adjOR = 3.89 95%CI = 1.26–11.95 p = 0.02) and mottling (adjOR = 3.80 95%CI = 1.06–13.55 p = 0.04) increased 30-day mortality odds. Conversely, fever (adjOR = 0.46 95%CI = 0.28-0.75 p = 0.002), fluid refractory hypotension (adjOR = 0.29 95%CI = 0.10–0.87 p = 0.027) and being diagnosed in surgical wards (adjOR = 0.35 95%CI = 0.15–0.81 p = 0.015) were protective. Treatment timeliness were not significant factors. Conclusion Several important predictors of 30-day mortality were found by this research. Retrospective analysis of our sepsis data has revealed mortality predictors that appear to be more patient-related than intervention-specific. With this information, care can be improved for those identified most at risk of death

Soil functions and ecosystem services research in the Chinese karst Critical Zone

Covering extensive parts of China, karst is a critically important landscape that has experienced rapid and intensive land use change and associated ecosystem degradation within only the last 50 years. In the natural state, key ecosystem services delivered by these landscapes include regulation of the hydrological cycle, nutrient cycling and supply, carbon storage in soils and biomass, biodiversity and food production. Intensification of agriculture since the late-20th century has led to a rapid deterioration in Critical Zone (CZ) state, evidenced by reduced crop production and rapid loss of soil. In many areas, an ecological ‘tipping point’ appears to have been passed as basement rock is exposed and ‘rocky desertification’ dominates. This paper reviews contemporary research of soil processes and ecosystems service delivery in Chinese karst ecosystems, with an emphasis on soil degradation and the potential for ecosystem recovery through sustainable management. It is clear that currently there is limited understanding of the geological, hydrological and ecological processes that control soil functions in these landscapes, which is critical for developing management strategies to optimise ecosystem service delivery. This knowledge gap presents a classic CZ scientific challenge because an integrated multi-disciplinary approach is essential to quantify the responses of soils in the Chinese karst CZ to extreme anthropogenic perturbation, to develop a mechanistic understanding of their resilience to environmental stressors, and thereby to inform strategies to recover and maintain sustainable soil function. © 2019 Elsevier B.V

Roadless wilderness area determines forest elephant movements in the Congo Basin

A dramatic expansion of road building is underway in the Congo Basin fuelled by private enterprise, international aid, and government aspirations. Among the great wilderness areas on earth, the Congo Basin is outstanding for its high biodiversity, particularly mobile megafauna including forest elephants (Loxodonta africana cyclotis). The abundance of many mammal species in the Basin increases with distance from roads due to hunting pressure, but the impacts of road proliferation on the movements of individuals are unknown. We investigated the ranging behaviour of forest elephants in relation to roads and roadless wilderness by fitting GPS telemetry collars onto a sample of 28 forest elephants living in six priority conservation areas. We show that the size of roadless wilderness is a strong determinant of home range size in this species. Though our study sites included the largest wilderness areas in central African forests, none of 4 home range metrics we calculated, including core area, tended toward an asymptote with increasing wilderness size, suggesting that uninhibited ranging in forest elephants no longer exists. Furthermore we show that roads outside protected areas which are not protected from hunting are a formidable barrier to movement while roads inside protected areas are not. Only 1 elephant from our sample crossed an unprotected road. During crossings her mean speed increased 14-fold compared to normal movements. Forest elephants are increasingly confined and constrained by roads across the Congo Basin which is reducing effective habitat availability and isolating populations, significantly threatening long term conservation efforts. If the current road development trajectory continues, forest wildernesses and the forest elephants they contain will collapse