Testing and analysis has been performed on square steel thin-walled tubes fabricated using symmetrically-overlapping U-channels and foam. This research analyzes flange-to-flange attachment, effect of foam in the columns, effect of adhesive stiffness, and influence of steel thickness, as related to the local buckling loads, global buckling loads, and crippling loads. Four 14-foot (4.27 m) foam-filled, thin-walled, galvanized steel columns were manufactured by Novatek, Inc. and tested in axial compression with pinned boundary conditions. For three of the four configurations, the two-piece 4-in. (10.2-cm) square shell surrounded prefabricated polystyrene foam inserts; the fourth column had no foam insert. The column outer shells were composed of two 16-gauge galvanized steel channels with overlapping flanges and the webs on opposite sides of the column. The two adjacent flanges on each side of the columns were adhesively bonded together in all cases. In addition to the adhesive, two columns had either periodic screws or short welds spaced evenly along the length of the columns to delay the onset of flange buckling of the outer channel, and potentially increase the compression strength. The other two columns had adhesive only bonding the flanges, one of which had no foam filler. The various configurations all exhibited similar compression strengths. Failure for all columns initiated with local buckling, followed by global buckling and local crippling, which occurred simultaneously. The method of flange attachment, the effect of the foam in the columns, and flange thicknesses were isolated and analyzed using mechanics-based analysis, parametric studies, and finite element analysis. The results show the ideal spacing of screws or short-welds, if used, is less than or equal to 5 in (12.7 cm) for the given column length. This increases the local buckling load to the Euler buckling load and preserves the original shape of the cross-section. The adhesive needs only a tensile strength of approximately 1 ksi (6.4 kPa) to prevent local buckling for any spacing of screws or short-welds, but needs to be applied uniformly (much of the adhesive in the column tests had been scraped off of the flanges during assembly). The results also show that foam core does not increase the Euler buckling load, but does increase the crippling load by delaying inward buckling of the column webs and flanges. Using foam with the given stiffness and a yield strength of 50 psi (345 kPa), uniform foam-to-steel bonding could increase the crippling strength up to 21% even without adhesive between the flanges. Using adhesive with the given stiffness between the flanges could increase the crippling strength by up to 63% without foam. The crippling strength could increase up to 72% if both adhesive between the flanges and a foam insert are used.

This dissertation focuses on improving the chromatographic efficiency of polymeric organic monoliths by characterizing and optimizing the bed morphology. In-situ characterization techniques such as capillary flow porometry (CFP), 3-dimensional scanning electron microscopy (3D SEM) and conductivity measurements were developed and implemented to quantitatively characterize the morphology of poly(ethylene glycol) diacrylate (PEGDA) monoliths. The CFP measurements for monoliths prepared by the same procedure in capillaries with different diameters (i.e., 75, 150, and 250 μm) clearly showed a change in average through-pore size with capillary diameter, thus, certifying the need for in-situ measurement techniques. Serial sectioning and imaging of PEGDA monoliths using 3D SEM gave quantitative information about the average pore size, porosity, radial heterogeneity and tortuosity of the monolith. Chromatographic efficiency was better for a monolith with smaller average pore size (i.e., 5.23 μm), porosity (i.e., 0.49), radial heterogeneity (i.e., 0.20) and tortuosity (i.e., 1.50) compared to another monolith with values of 5.90 μm, 0.59, 0.50 and 2.34, respectively. Other than providing information about monolith morphology, these techniques also aided in identifying factors governing morphological changes, such as capillary diameter, polymerization method, physical/chemical properties of the pre-polymer constituents and weight proportion of the same. A statistical model was developed for optimizing the weight proportion of pre-polymer constituents from their physical/chemical properties for improved chromatographic efficiency. Fabricated PEGDA columns were used for liquid chromatography of small molecules such as phenols, hydroxyl benzoic acids, and alkyl parabens. The chromatographic retention mechanism was determined to be principally reversed-phase (RP) with additional hydrogen bonding between the polar groups of the analytes and the ethylene oxide groups embedded in the monolith structure. The chromatographic efficiency measured for a non-retained compound (uracil) was 186,000 plates/m when corrected for injector dead volume. High resolution gradient separations of selected pharmaceutical compounds and phenylurea herbicides were achieved in less than 18 min. Column preparation was highly reproducible, with relative standard deviation (RSD) values less than 2.1%, based on retention times of the phenol standards (3 different columns). A further improvement in chromatographic performance was achieved for monoliths fabricated using a different polymerization method, i.e., living free-radical polymerization (LFRP). The columns gave an unprecedented column performance of 238, 000 plates/m for a non-retained compound under RP conditions.

It is possible to reduce residual and maximum drifts in buildings by adding “elastic stories” that engage gravity columns in seismic response. An elastic story is a story wherein the buckling restrained brace frame (BRBF) size is increased to prevent yielding when an earthquake occurs. Buildings ranging from 4–16 stories were designed with various elastic story brace sizes and locations to determine the optimal combination to best reduce drifts. Gravity column stiffnesses were also varied in elastic story buildings to determine the effects on drifts. Computer models were used to analyze these buildings under a suite of earthquakes. Adding elastic stories reduce residual drifts 34% to 65% in 4- to 16-story BRBF buildings. General recommendations are made to achieve optimal reductions in drifts. For buildings with six or more stories, drifts were generally reduced most when an elastic story was added to every 4th story starting at level 1 (the bottom story). The most effective size for the braces in the elastic story appears to be three times the original brace size. For buildings with less than six stories, adding a three times elastic story to the bottom level was observed to reduce drifts the most. Further research is also recommended to confirm the optimal location and size of elastic stories for buildings with differing number of stories. Increasing gravity column stiffnesses in buildings with elastic stories helps to further reduce drifts, however it may not be economical. Residual drifts were observed to decrease significantly more than maximum drifts when elastic stories were added to buildings. Maximum drifts generally decreased at some levels, but also increased at others when elastic stories were used.

Electrostatic charge generation in gas-solid fluidized beds is a significant industrial problem. Associated problems include particle agglomeration and particle wall fouling. In the polymerization industry this may result in "sheets" of fused polymer, due to exothermic reaction causing the melting of the polymer, which can fall off and block the distributor plate disrupting fluidizing gas flow. Additionally, blockage of the catalyst feed or the polymer removal system can take place or the product can become non-uniform. All of these problems require shut-down of the reactor which results in lost production time. While this phenomena has been identified for many years, the mechanisms involved are not well understood, especially wall fouling and the distribution of charge within the bed. Isolation of individual parameters such as hydrodynamics, operating conditions, and material involved is necessary to evaluate how each parameter impacts charge generation during fluidization. In this thesis, the fluidization system consisted of a stainless steel column, two online Faraday cups, and a retractable distributor plate. This system allowed for the simultaneous measurement of charge within different regions of the bed: the entrained fine particles, the particles adhered to the column wall, and the bulk of the bed. Additionally, mass and particle size distributions were measured and images of the layer of particles adhered to the column wall were taken for comparison. This allowed for a charge distribution comparison and evaluation of wall fouling. Three different parameters were investigated: duration of fluidization, column wall material, and relative humidity of fluidizing gas. Fluidization time was studied for 15, 30, 60, 120, 180, and 360 min; relative humidity was investigated for 0%, 20%, 40%, 60%, and 80% relative humidity. Both fluidization time and relative humidity were evaluated at four different fluidization gas velocities, two each in the bubbling and slugging flow regimes. Column wall material was evaluated for a stainless steel and carbon steel column at two gas velocities, one each in the bubbling and slugging flow regimes. Fluidization time was found to influence wall fouling in the bubbling flow regime as the particle layer continued to build as fluidization progressed. In the slugging flow regime, the particle layer developed within 15 minutes of the onset of fluidization. The bubbling flow regime was shown to have a greater capacity for charge generation than the slugging flow regime. This was due to the vigorous mixing in the bubbling flow regime resulting in more particle-particle interactions. Column wall material was shown to influence wall fouling in the slugging flow regime due to the differences in surface roughness of the columns. This was due to the particle-wall contacts resulting in frictional charging which is the predominant charging mechanism in this flow regime. Charge was also impacted in the bubbling flow regime in those particles that were adhered to the column wall. Relative humidity was found to influence wall fouling at the lowest gas velocity tested. However, variations in generation of charge occurred at all fluidization gas velocities tested; the charge-to-mass ratios for the particles adhered to the column wall in the slugging flow regime decreased with high relative humidities. This was due to either the formation of a water film layer on the column wall or instantaneous surface water films on the particles throughout fluidization.

They seek to embrace and understand the complexity of the man-made. They live alongside one another in a cluster - reflecting, synthesizing, producing and celebrating. They created their spaces and hierarchies through the basic principles of the wall and the column. The Sanctuary of the Man-made is an exploration of elements through a narrative that aims for a deeper understanding of human built complexity.

[pt] Compreensão de dados, codificação digital da fala, telecomunicações via celular, correção de erros de transmissão, são algumas das aplicações práticas do estudo dos códigos de cobertura, um importante ramo da área da matemática denominada teoria dos códigos. Neste trabalho são abordados dois problemas de códigos de cobertura: o problema clássico de códigos de cobertura e o recente problema denominado de códigos curtos de cobertura. Apresenta-se uma aplicação da metaeurística Busca Tabu Reativa, uma importante variação da Busca Tabu clássica, para os problemas citados. Além disto, apresenta-se uma nova técnica heurística para resolução de problemas de otimização combinatória denominada Heurística de Melhoria via Geração de Colunas (HMGC), juntamente com uma aplicação da mesma aos problemas em questão. A HMGC combina a geração atrasada de colunas, técnica usada na resolução de problemas com um grande número de variáveis de decisão (colunas), e heurísticas de busca local. É feita uma comparação dos resultados obtidos pela Busca Tabu Reativa, a Busca Tabu sem o mecanismo de reação e a HMGC, de forma a avaliar a qualidade das heurísticas apresentadas. / [en] Data compression, speech coding, móbile telecommunications and error-corretion are some of the practical apllications of the covering codes study, an important field of coding theory. This work addresses two problems of covering codes: the classic code covering problem and the recent short code covering problem. It presents an application of Reactive Tabu Search (RTS) metaheuristic for the problems cited, the RTS is an important variation of the classic Tabu Search. Moreover, it presents a new heuristic technique for solving combinatorial optimization problems named Column Generation Improbement Heuristic (CGIH). It also presents an application of CGIH for the covering codes problems. The CGIH combines the delayed column generation, technique used to solve problems with a large number of decision variables (columns), and local search heuristics. A comparison of results obtained by the Reactive Tabu Search, the Tabu Search without the reaction mechanism and the CGIH is also presented in order to assess the effectivenss of the presented heuristics.

It is fundamental to investigate the biodegradability of chemicals and their potential (eco)toxicological effects under near-environmental conditions in order to identify and thereby avoid potential risks to humans, animals and the environment in the event of their release. Established as a policy object at the European level, the risks, which are posed by anthropogenic pollution, ideally need to be reduced to a minimum, if not eliminated completely, in the near future. To achieve this goal, an assessment of chemicals, based on international consensus, is required, which builds on the results of standardized experiments and is constantly supplemented by computer-based approaches. Establishing structure-property relationships is one way to immediately classify organic trace substances as ‘degradable’, or ‘potentially persistent’, as well as as hormonally ‘active’ or ‘inactive’. The extent to which these relationships are applicable to the substance group of benzophenone-type UV filters was investigated in this work. Some derivatives, which only differ in the type and position of their substituents on the aromatic rings, are suspected of acting as endocrine disruptors. Despite the high probability of them being released into the environment, and the toxicologically relevant properties, there are no mechanistic degradation studies so far that take enough derivatives into consideration to discuss the substitution pattern as a possible influential factor. To close the identified gaps, experiments on primary as well as ultimate degradation were carried out with up to ten different benzophenones, changing various parameters and adapting the experimental setup. Studies on the complete mineralizability, compliant with the standardized OECD Guideline No. 301F, showed that the respective substitution pattern is a decisive factor, while the mere presence of certain functional groups plays a minor role. To yield additional information on the time-dependent formation of primary degradation products, an LC-MS/MS method was developed that served to quantify benzophenones in various environmental matrices during a monitoring campaign, in addition to tracking primary degradation at the laboratory scale. The detection of 4-hydroxybenzophenone, which meets the structural criteria for multi-hormonal effects and was identified as a microbial degradation product of benzophenone, confirmed that the formation of transformation products needs to be given greater consideration in relation to toxicological issues. On this evidence, the structure-dependent endocrine effects of benzophenone-type UV filters, the transformation product 4-hydroxybenzophenone, and three other degradation products were determined using recombinant yeast-based reporter gene assays. Hydroxyl groups are the prevalent substituents of benzophenone-type UV filters, and the ruling structural elements, which influence microbial biodegradation and endocrine activity. Their investigation revealed a new fundamental but unexpected relationship: Primary degradation can slow down further degradation through the incorporation of hydroxyl groups. This simultaneously increases the risk of a formation of estrogen-active transformation products. This aspect underlines the need to include the occurrence of transformation products, especially under realistic conditions, in the overall risk assessment of chemicals. In this context, the application of quantitative structure-activity relationships (QSAR) plays a crucial role and, the suitability thereof was verified in this work – focusing on benzophenones. The empirically proven relationship between substitution pattern and degradability helps to improve the reliability of QSAR models for benzophenones as well as for structurally similar compounds, and forms the basis for further studies of this specific relationship at the enzymatic level.:DECLARATION OF CONFORMITY DECLARATION OF INDEPENDENT WORK PREFACE ACKNOWLEDGMENT KURZFASSUNG ABSTRACT LIST OF ABBREVIATIONS AND ACRONYMS 1 CONTEXTUAL FRAMEWORK AND OBJECTIVES 2 STATE OF KNOWLEDGE ABOUT THE BIODEGRADATION OF BENZOPHENONES 2.1 INTRODUCTION 2.2 ENTRY PATHS INTO THE ENVIRONMENT AND HAZARDOUS EFFECTS 2.2.1 Environmental occurrence and possible routes of discharge 2.2.2 (Eco)toxicity and endocrine disrupting properties 2.3 BIODEGRADATION 2.3.1 Aerobic biotransformation 2.3.2 Anoxic/anaerobic biotransformation 2.3.3 Transformation mediated through fungi and higher organisms 2.4 PHOTOLYTIC TRANSFORMATION 2.5 CONCLUSIONS 3 TRACE ANALYSIS IN ENVIRONMENTAL SAMPLES AND THE ENDOCRINE EFFECTS 3.1 INTRODUCTION 3.2 MATERIAL AND METHODS 3.2.1 Chemicals and materials 3.2.2 LC-MS/MS method development 3.2.2.1 MS parameters 3.2.2.2 LC parameters 3.2.2.3 Sample preparation 3.2.2.4 Validation 3.2.2.5 Application of the method to environmental monitoring 3.2.3 Biodegradation 3.2.4 Yeast-based reporter gene assays 3.3 RESULTS AND DISCUSSION 3.3.1 LC-MS/MS method development 3.3.1.1 Sample preparation 3.3.1.2 Validation 3.3.1.3 Application of the method for environmental samples 3.3.2 Biodegradation 3.3.3 Endocrine activity 3.3.3.1 Estrogenic and antiestrogenic activities 3.3.3.2 Estrogenic activity during biotransformation 3.3.3.3 Androgenic and antiandrogenic activities 3.4 CONCLUSION 4 PRIMARY AND ULTIMATE DEGRADATION 4.1 INTRODUCTION 4.2 MATERIAL AND METHODS 4.2.1 Chemicals and materials 4.2.2 Primary degradation 4.2.2.1 Abiotic river water 4.2.2.2 Biotic river water 4.2.2.3 Suboxic river water 4.2.2.4 River water amended with mineral solution 4.2.3 Ready biodegradability 4.2.4 Column experiments 4.2.5 Docking studies 4.2.6 LC-MS/MS Analysis 4.3 RESULTS AND DISCUSSION 4.3.1 Primary degradation 4.3.1.1 Abiotic river water 4.3.1.2 Biotic river water 4.3.1.3 Suboxic river water 4.3.1.4 River water amended with mineral solution 4.3.2 Ready biodegradability 4.3.3 Column experiments 4.3.3.1 Breakthrough curves and pretests 4.3.3.2 Removal tests 4.3.4 Structure-biodegradability relationships 4.4 CONCLUSIONS 5 SYNTHESIS 5.1 SUMMARIZING DISCUSSION 5.2 COMPARISON TO IN SILICO RESULTS 5.2.1 Biodegradability 5.2.2 Estrogenicity 5.3 CONCLUSION 6 APPENDIX 6.1 APPENDIX A 6.2 APPENDIX B 6.3 APPENDIX C 6.4 APPENDIX D 7 REFERENCES

This paper is concerned with the behaviour of beam ¿ column connections of steel ¿ concrete composite beams with precast hollow core slabs. Experiments were carried out to investigate the joint rotation characteristics and ultimate moment capacity of these connections. Details of the test specimens, instrumentation, test set-up and test procedures are described. Results obtained for the connection moment capacity, rotation capacity and failure modes are presented. It is found that through proper design and detailing, these simple steel connections display the characteristics of a semi-rigid connection with very little extra cost.

Yes / Elliptical Hollow Sections (EHSs) have been utilized in construction recently because of their visual appearance as well as the potential structural efficiency owing to the presence of the two principle axes. However, little information currently exists for the design of beam to elliptical column connections, which is an essential part of a building structure. Thus, to ensure the safe and economic application of EHSs, a new research project has been initiated. Rotation behaviour of simply bolted beam to concrete-filled elliptical steel column connections was investigated experimentally. Various joint types were considered and the benefits of adopting core concrete and stiffeners were highlighted. This paper covers the experimental studies and simulation of the connections using the ABAQUS standard solver. Comparisons of failure modes and moment vs. rotation relationships of the connections between numerical and experimental results were given. Good agreement has been obtained and the developed finite element model was therefore adopted to conduct a preliminary parametric study to explore the effect of critical parameters on the structural behaviour of beam to concrete-filled elliptical column connections.

Yes / This paper investigated the rotation behaviour of simply bolted I-beam to concrete-filled elliptical steel tubular (CFEST) column connections experimentally. Ten different joint assemblies were tested to failure, with a constant axial compressive load applied to the column and upwards concentrated loads at the beam ends. All of the steel tubes were hot-finished and had a cross-sectional aspect ratio of 2. The orientation of the column and the arrangement of the stiffening plates were taken into consideration. Moment versus rotation relationships and failure modes were compared for each joint, highlighting the benefits of using core concrete and stiffeners in these connections.