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Low Impact Development (LID) techniques for site design are increasingly being utilized to mitigate the negative impacts associated with stormwater runoff, and green roofs are one such application. The ability of green roofs to reduce the total and peak volumes of stormwater runoff has been fairly well documented, but performance varies in different climate zones, and there is limited information available regarding green roof effectiveness in New England, a region whose weather patterns are notoriously variable from season to season and often even day-to-day. Additionally, there are questions regarding the impact that green roofs have on water quality, especially regarding phosphorus. While many green roofs have been found to leach phosphorus into stormwater runoff within the first few years after installation, it is assumed that this phenomenon will not continue after the green roof vegetation has been established. However, it is still unclear whether or not this assumption is valid, and very few research projects have focused on providing the necessary insight into the hydrologic and geochemical processes that are contributing to this observed problem. The Nitsch/Magliozzi Green Roof, located atop WPI's newest residence hall, was donated to enhance the sustainability of the building and to foster continued research and education. This roof provided an opportunity to better characterize the relationship between rainfall and runoff volumes, phosphorus sorption/desorption in the growing medium, and plant uptake processes. Comparisons of grab samples of stormwater from both the green and non-green portions of the roof within the first few seasons following installation confirmed that phosphorus was leaching into the runoff, and some seasonal trends were observed. For example, the highest concentrations (3-13 mg/l P-PO4-3) were observed during an especially rainy summer. In order to gain a better understanding into the nature of this occurrence, laboratory experiments on sections of this same green roof were designed and set up in WPI's greenhouse. A series of simulated rainfall events were conducted, a mass balance approach was used to analyze flow, and the phosphorus content of the water, plants, and soil were assessed. For flow attenuation, the green roof panels performed as expected under different rainfall and antecedent moisture conditions. Additionally, the greenhouse experiments provided improved insight into the nature of the relationship of phosphorus between the flow conditions, plant uptake, and soil processes, as well as its distribution throughout a storm. The laboratory data further provides a basis for estimating performance of a green roof and its long-term impact on stormwater quality. In a broader context, the findings also serve to inform future extensive green roof designs and subsequent research efforts.

The Swedish winters 2009/10 and 2010/11 were rich in snow and many roofs collapsed, mainly largespan frames. Investigations were made and the amount of snow was not the primary cause, insteadthere were several other causes. One of these was that in some cases roofs were shoveled in anunfavorable manner which affected the load patterns negatively, so causing the roofs to collapse.Most people lack the knowledge of how shoveling will affect the roof. Had there been an increasedunderstanding regarding shoveling, some roofs could have been prevented from collapsing. Through both qualitative and quantitative research in the form of interviews and calculations thetheoretically best ways to shovel a selection of roof types is presented in the report. The roofstructures covered are 3-compartment, continuous and Gerberspliced metal roof decks. Thecalculations only concern the bending moments in the decks. The results show that differentmethods are required depending on the type of structure. Therefore it is very important to knowwhat kind of a building is to be shoveled. To ensure that this information should be easy to understand and apply, a template has beendesigned with tips and advice for the structural engineer on how to establish a plan for shoveling.The plan for shoveling should then be passed on to the property owner with instructions, tips andadvice on how to attend to his property before, during and after the snow has fallen.

The objective of this research is to develop a flexible design grammar and genetic algorithm representation to be used in a multi-objective optimization method to design efficient steel roof trusses given space dimensions and loading requirements by the user. The goal of implementing the method as a multi-objective problem is to obtain a set of near-optimal trusses for the defined unstructured problem domain, not just a single near-optimal design. The method developed was required to support the exploration of a broad range of conceptual designs before making design decisions. Therefore, a method was developed that could define numerous design variables, support techniques to locate global or near-global optimal designs, and improve the efficiency of the computational procedures implemented. This research effort was motivated by the need to consider structural designs that may be beyond the established conventions of designers in the search for cost-efficient, structurally-sound designs. An effective design grammar that is capable of generating stable trusses is defined in this research. The design grammar supports the optimization of member size, in addition to truss geometry and topology. Multi-objective genetic algorithms were used to evolve sets of Pareto-optimal trusses that had varying topology, geometry, and member sizes. The Pareto-optimal curves provided design engineers with a range of near-optimal design alternatives that showed the tradeoffs that occur in meeting the stated objectives. Designers can select their final design from this set based on their own individual weighting of the design objectives. Trials are performed using a multiobjective genetic algorithm that works with the design grammar to evolve trusses for different span lengths. In addition to evaluate the performance of the developed optimization method further, trials were performed on a benchmark truss problem domain and the results obtained were compared with results obtained by other researchers. The results of the performance evaluation trials for the proposed method, in which the sizing, shape and topology were simultaneously performed, indicated that the method was effective in evolving a variety of truss topologies compared to previous published results, which evolved from a ground structure. The diverse topologies, however, were obtained over several trials instead of being found in a Pareto-optimal set found by a single trial. In addition, the proposed method was not able to locally optimize the member section sizes. Additional trials were performed to determine the benefit of applying local optimization to the member section sizes for a given truss topology or geometry provided by the method. The results indicate that significant weight reduction could be achieved by performing local optimization to the truss designs obtained by the proposed multi-objective optimization method.

Twenty two substrates were developed and tested for two different green roof plant production methodologies. Growth rate analysis of Sedum sp. revealed distinct differences in performance of the mat substrates across a two year time frame with substrate water holding capacity (v/v) being a primary promoter of rapid mat coverage. Tray substrate analysis revealed numerous component options provided similar production speeds, with diverse and beneficial physical properties being described. Zebra and Quagga mussel shells proved to be a sustainable and beneficial component option for both mat and tray substrates. Further substrate component identification resulted in Biochar being investigated for its potential use in green roof media mixtures. The additions of incremental amounts of biochar into control substrates reduced bulk density by up to 20%, while simultaneously increasing volumetric water holding capacity to 54%, 12% greater than that of the control. Sedum plant growth in biochar revealed the lowest shoot dry weights resulting from no biochar additions. Substrate and plant water relationships were explored further with four substrates being planted with four diverse herbaceous and succulent plant communities. Substrate composition and plant community was observed to significantly affect dry down rates. / OMAFRA

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Thesis (Doktor-Ingenieur)--Technische Hochschule, Stuttgart. / Lebenslauf.