The objectives of this research were to determine the required net lateral restraining force to brace j-webs or j-chords braced by one or more continuous lateral braces (CLB's), and to develop a methodology for permanent bracing design using a combination of lateral and diagonal braces. SAP2000 (CSI, 1995), a finite element analysis program, was used to analyze structural analogs for three sets of truss chords braced by n-CLB's and one or two diagonals, one web braced by one and two CLB's, and j-truss chords braced by n-CLB's. System analogs used to model five eight-foot truss chords braced by three CLB's and one diagonal, six twenty-foot truss chords braced by nine CLB's and two diagonals, and eleven twenty-foot truss chords braced by nine CLB's and two diagonals were analyzed. For each of the three cases analyzed, the chord lumber was assumed to be 2x4 No. 2 Southern Pine (S. Pine) braced by 2x4 STUD Spruce-Pine-Fir (SPF). Chord load levels of 10% to 50% of the allowable compression load parallel-to-grain assuming le/d of 16 were studied. All wood-to-wood brace connections were assumed to be made with 2-16d Common nails. A nonlinear load-displacement function was used to model the behavior of the nail connections. Single member analogs were analyzed that represented web members varying in length from four-feet to twelve-feet braced by one and two CLB's. The web and CLB's were assumed to be 2x4 STUD SPF. The web members were also analyzed assuming 2x6 STUD SPF. Single member analogs were analyzed that represented chord members varying in length from four-feet to forty-feet braced by n-CLB's spaced twenty-four inches on-center. The truss chord was assumed to be No. 2 Southern Pine and the CLB's were assumed to be STUD SPF. The chord size was varied from 2x4 to 2x12 and connections were assumed to consist of 2-16d Common nails. The system analog analysis results were compared to the single member chord analysis results based on the number of truss chords and the diagonal brace configuration. For the three cases studied involving multiple 2x4 chords braced as a unit (and believed to be representative of typical truss construction), the bracing force from the single member analog analysis was a conservative estimate for bracing design purposes. It was concluded that the single member analysis analog yields approximate bracing forces for chords larger than 2x4 and for typical constructions beyond the three cases studied in this research. For analysis and design purposes, a ratio R was defined as the net lateral restraining force per web or chord divided by the axial compressive load in the web or chord. For both 2x4 and 2x6 webs braced with one CLB, the R-value was 2.3% for all web lengths studied. For both 2x4 and 2x6 webs braced with two CLB's, the R-value was 2.8% for all web lengths studied. The web and CLB lumber species did not affect the R-values for the braced webs. Calculated R-values for truss chords, 2x4 up to 2x12, braced by n-CLB's assumed to be spaced two feet on-center for chords four to twelve feet in length ranged from 2.2% to 3.0%, respectively. For chords from sixteen to forty feet in length, R ranged from 3.1% to 2.6%, respectively. The lumber species and grade assumed for the chord and CLB did not affect the R-values for the truss chords. Step-by-step design procedure was developed for determining the net lateral restraining force required for bracing j-chords based on the results of the single member analogs studied. The required total lateral restraining force for j-compression members in a row can be calculated based on the R-value for or the number of CLB's installed at 2 feet on-center, the design axial compression load in the chord, and number of trusses to be braced. / Master of Science

This study examines the relationship between environmental sustainability and green schools, seeking to highlight the benefits and determine the Net Present Value (NPV) installing vegetative roofs on all schools in the Atlanta Public Schools District. This study quantifies the costs and benefits of thin-layer, or extensive, green roof systems as they compare to typical flat roofs on Atlanta Public Schools. Quantifiable benefits are detailed and suggestions are made to create the means by which other social benefits may be quantified. The purpose of this thesis is to establish proof to the Atlanta Public Schools District that over a 40 year period there are more benefits associated with installing vegetative roofs on all of their flat roofs than there are costs. While some may argue that greens roof are more costly than traditional roof systems, this study provides evidence that the cumulative benefits over a 40 year life cycle associated with large scale green roof installations, such as on all Atlanta Public Schools, are greater than the initial costs incurred. Factors included in the analysis of benefits were reductions to energy/utility costs, reduced emissions, and avoided best management practices (BMPs). Other considerations include social benefits resulting from the mitigation of storm water runoff, reductions to the urban heat island, productivity level increases (students and teachers), and avoided regulatory fees.

Thesis (M.S.)--Mississippi State University. Department of Civil Engineering. / Title from title screen. Includes bibliographical references.

Stormwater management is an essential aspect of urban hydrology. Urbanized areas have large amounts of impervious surface cover (ISC) and well developed sewer and drainage networks which rapidly channel water and pollutants off of streets and into local streams. This research evaluates the use of vegetated roofs as mechanisms to reduce ISC and stormwater runoff in downtown Atlanta. A 3-D model of the study site was created so that runoff rates could be measured for various rooftop scenarios under different size storm events. The results revealed a reduction in peak runoff and an increase in both the lag time and duration of response time. The results were most significant for the smallest storm event with 2/3 of the rooftops vegetated. As these experiments use a scale model for a section of downtown Atlanta, results are likely to be applicable to similar urban environments and may provide guidance for stormwater engineers.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Geography." Includes bibliographical references (p. 119-124).

The base tGSt method has been proposed by Carballo, Holzer and Murray [5] as a means of determining the strength of standing seam roof systems under gravity loading. The objective of this thesis is to evaluate the accuracy of the base test method. To do this, eleven sets of tests were performed at Virginia Polytechnic Institute & State University (VPl&SU). Each test set consisted of a single span base test from which a failure load was predicted for the corresponding three span confirming test. Results of two test sets recorded in Reference [5] were also used to evaluate the method. A secondary objective of this thesis is to comment on the effects that system components (purlin orientation, clip type, bracing configuration, panel type, insulation and purlin type) have on the strength of the system. Results from proprietary tests conducted at VPI & SU were used in conjunction with the results from this research to accomplish the secondary objective. / Master of Science

Modernamente os cabos vêm sendo empregados como elemento portante de coberturas de grandes vãos - as coberturas pênseis. É finalidade deste trabalho a apresentação da análise estática de cabos livremente suspensos, visando à sua aplicação nestas coberturas. Realiza-se o estudo de cabos - submetidos a carregamento estático uniformemente distribuído em todo o seu vão, a variações de temperatura e a deslocamentos de seus apoios - através do Processo Analítico (equações diferenciais) e do Processo dos Deslocamentos (rigidez tangente). Considera-se a não linearidade geométrica e admite-se a linearidade física. A comparação e análise dos resultados destes processos de cálculo são feitas através de experimentação numérica. / Nowadays cables have been utilized as a resistant element in roofs of large dimensions, the hanging roofs. The objective of this work is to present the static analysis of suspended cables, aiming their application in roofs. A study of cables subjected to static uniform load distributed on the length, variations of temperature and displacements of the supports is done through Analytical Process (differential equations) and Stiffness Process (tangent stiffness). Geometrical non-linear analysis is allowed and physical linear analysis is admitted. The results are compared and analysed through numerical experimentation.

Modernamente os cabos vêm sendo empregados como elemento portante de coberturas de grandes vãos - as coberturas pênseis. É finalidade deste trabalho a apresentação da análise estática de cabos livremente suspensos, visando à sua aplicação nestas coberturas. Realiza-se o estudo de cabos - submetidos a carregamento estático uniformemente distribuído em todo o seu vão, a variações de temperatura e a deslocamentos de seus apoios - através do Processo Analítico (equações diferenciais) e do Processo dos Deslocamentos (rigidez tangente). Considera-se a não linearidade geométrica e admite-se a linearidade física. A comparação e análise dos resultados destes processos de cálculo são feitas através de experimentação numérica. / Nowadays cables have been utilized as a resistant element in roofs of large dimensions, the hanging roofs. The objective of this work is to present the static analysis of suspended cables, aiming their application in roofs. A study of cables subjected to static uniform load distributed on the length, variations of temperature and displacements of the supports is done through Analytical Process (differential equations) and Stiffness Process (tangent stiffness). Geometrical non-linear analysis is allowed and physical linear analysis is admitted. The results are compared and analysed through numerical experimentation.

Increased urbanization leads to an increasing amount of impervious surfaces and a decrease ofthe natural hydrological function. Urban stormwater does thus risk to create high surface flows which could damage the receiving water bodies (e.g. erosion) or the urban area itself (flooding). Integrating more nature-based systems into the urban area increases the natural hydrological function and the risks for high surface flows are lowered. One way of implementing nature-based systems in the urban environment is to install green roofs. Most of the research and development done on green roofs have been focusing on the conditions of central Europe. Installing green roofs with the same vegetation in the subarctic climate of northern Sweden would expose it to a climate it might not be suited for, and growth would be limited. The vegetation helps increase the retaining and detaining capabilities of the green roofs and therefore the purpose of this thesis was to examine if planting native vegetation would help increase thegreen roofs performance in a subarctic climate. Conventional green roofs vegetated with sedum was hypothesized to have lessened retaining and detaining capabilities when placed in cold climates since the vegetation was exposed to a climate it probably was not suited for. It was examined whether planting more native vegetation could help increase green roofs performance. The vegetation was chosen based on Grime´s “universal adaptive strategy theory”, which describes competitors, stress tolerators and ruderals as three different vegetation groups with different survival strategies. Different species from each strategy were selected and planted on the roofs. There were five roofs per survival strategy and five roofs where all strategies were mixed. Conventional sedum vegetation was planted on five roofs to be able to compare green roofs performance. Five control roofs with substrate only and one reference roof made of steel were installed as well. In total, seven rainfall events were analyzed, and few significant differences could be found between the competitors, stress tolerators, ruderals and the vegetation mix. A conclusion is that stress tolerators may help to increase green roof performance the most, but due to the relatively short study period, continued measurements are recommended to draw further conclusions. The survival strategies did improve retention and detention relatively to using sedum vegetation and substrate only. The extent of vegetation coverage does not affect the retention or detention from the green roofs. The competitors, stress tolerators, ruderals and vegetation mix had larger plant mass than the sedum and the increased plant mass is probably the reason for their improved retention.

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