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Triax dome modeling with I-DEAS 4.1Broyles, Donald L. 03 March 2009 (has links)
With the increasing need for large columnless structures in today's society, glued-laminated Triax domes are being designed and built. Even though many have already been constructed, no methods have been established to accurately determine the ultimate load capacity or the factor of safety.
Several ABAQUS finite element analyses have been conducted at Virginia Polytechnic Institute and State University to determine these values (Davalos, 1989). The work in this area has been slowed due to the absence of a preprocessor for the creation of the input data file. The use of a preprocessor could greatly accelerate the analysis process and prove to be more efficient.
The primary objective of this thesis is to present a clear detailed procedure for the creation of the input data file using the Integrated Design Engineering Analysis
Software package (I-DEAS) version 4.1. In addition to meeting this objective, several other topics concerning I-DEAS modeling guidelines and post processing features are discussed. The results oT a linear finite element analysis is also presented.
The use of a preprocessor is essential for the creation of the triax input data fiIe. I-DEAS can not only meet this challenge, but can provide assistance in all facets of finite element modeling. / Master of Science
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Geometrically nonlinear finite element analysis of a glulam timber domeDavalos, Julio F. January 1989 (has links)
A finite element modeling and geometrically nonlinear static analysis of glued-laminated timber domes is presented. The modeling and analysis guidelines include: the generation of the geometry, the selection of finite elements to model the components of a dome (beams, purlins, connections, and tension ring), the specification of boundary conditions, the specification of material properties, the determination of a sufficiently accurate mesh, the determination of design loads and the specification of load combinations, the application of analysis procedures to trace the complete response of the structure, and the evaluation of the response. The modeling assumptions and analysis procedures are applied to a dome model whose geometry is based on an existing glulam timber dome of 133 ft span and 18 ft rise above the tension ring. This dome consists of triangulated networks of curved southern pine glulam members connected by steel hubs. The members lie on great circles of a spherical surface of 133.3 ft radius. The dome is covered with a tongue-and-groove wood decking, which is not considered in this study. Therefore, the surface pressures are converted into member loads and then discretized into nodal concentrated loads.
A geometrically nonlinear, 3-d, 3-node, isoparametric beam element for glulam beams is formulated, and a program is developed for the analysis of rigid-jointed space frames that can trace the response of the structure by the modified Newton-Ralphson and the modified Risk-Wempner methods. The material is assumed to be continuous, homogeneous, and transversely isotropic. The material properties are assumed to be constant through the volume of the element. The transverse isotropy assumption is validated for southern pine by testing small samples in torsion. The accuracy of the modeling assumptions for southern pine glulam beams is experimentally verified by testing full-size, curved and straight, glulam beams under combined loads. The results show that the isobeam element can accurately represent the overall linear response of the beams. However, to analyze glulam domes with the program, connector elements to model the joints and a truss element to model the tension ring must be added. Therefore, the finite element program ABAQUS is used for the analysis of the dome model.
Three dead-load/snow-load combinations are considered in the analysis of the dome model. The space frame joints and the purlin-to-beam connections are modeled with 2-node isobeam elements. A 3-d, 2-node, truss element is used to model the tension ring. Three distinct analyses are considered for rigid and flexible joints: a linear analysis to check the design adequacy of the members. A linearized eigenvalue buckling prediction analysis to estimate the buckling load, which provided accurate estimates of the critical loads when rigid joints were specified. Finally, an incremental, iterative, geometrically nonlinear analysis to trace the complete response of the structure up to failure. It is shown that elastic instability, which is governed by geometric nonlinearities, is the dominant failure mode of the test dome. At the critical load, the induced element stresses remained below the proportional limit of the material. A discussion of the results is presented, and recommendations for future extensions are included. / Ph. D.
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Exhumation of the Orlica-Snieznik Dome, northeastern Bohemian massif (Poland and Czech Republic) /Glascock, Jacob M. January 2004 (has links)
Thesis (M.S.)--Ohio University, November, 2004. / Includes bibliographical references (p. 67-72)
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Exhumation of the Orlica-Snieznik Dome, northeastern Bohemian massif (Poland and Czech Republic)Glascock, Jacob M. January 2004 (has links)
Thesis (M.S.)--Ohio University, November, 2004. / Title from PDF t.p. Includes bibliographical references (p. 67-72)
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Stability analysis of the Church of the Nazarene Varax domeTissaoui, Jacem 24 October 2009 (has links)
The object of this study is to investigate the stability of the Church of the Nazarene Varax dome under various load distributions. A model of the dome constructed using I-DEAS is presented and results of linear and nonlinear analyses are discussed. A comparison between the critical load obtained using nonlinear analysis and combined linear and nonlinear analysis is made. The model is modified to include flexible joints and bracing to model the decking. The effect of these modifications on the critical load is discussed. / Master of Science
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Origin and evolution of the Santiaguito lava dome complex, GuatemalaScott, Jeannie A. J. January 2013 (has links)
Subduction zone volcanoes are a major natural hazard, frequently endangering lives and livelihoods. The eruptive history of many subduction zone volcanoes includes the extrusion of blocky, silicic lava that forms domes or flows, but we do not yet understand what determines the duration of dome-forming behaviour, what path magma may take to the surface, or how these systems may change over time. This thesis presents an investigation of the Santiaguito complex of lava domes and flows in Guatemala, which has been erupting continuously since its inception in 1922. The Santiaguito lavas are predominantly dacitic to andesitic, with a gradual reduction in SiO2 content from ~66 wt% in the 1920s, to ~62 wt% in 2002. This is consistent with a ~15% decrease in the extent of fractional crystallization over that time. The compositions of plagioclase phenocryst cores indicate a diminished role for magma mixing after the 1940s. I model the Santiaguito system as progressively extracting magma from an extensive, chemically-stratified storage zone. Petrological data are consistent with a storage zone extending from ~25 to ~12 km depth, and magma storage temperatures of ~940 to ~980°C. Phenocryst-hosted apatites suggest melt in this storage zone contained 401 to 1199 ppm S, 600 to 1300 ppm F, and 4100 to 6200 ppm Cl. Ascending magma may pass slowly through a conduit bottleneck, or plug, at shallow depths; groundmass texture suggests that melt rigidifies at or near the base this plug. Pre-eruptive melt volatile concentrations suggest time-averaged fluxes of 40 to 263 Mg d-1 SO2, 32 to 145 Mg d-1 HF, and 247 to 708 Mg d-1 HCl, giving ratios of 0.6 to 0.8 HF/SO2, and 2.7 to 6.2 HCl/SO2. These results are consistent with the few direct measurements of SO2 at Santiaguito, and with measured halogen emissions from other silicic dome-forming systems.
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Structural geology of the Usakos Dome in the Damara Belt, NamibiaJohnson, Shannon D. 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: The northeast-trending south Central Zone (sCZ) of the Pan-African Damara belt in
central Namibia is structurally characterized by kilometer-scale, northeast-trending dome
structures developed in Neoproterozoic rocks of the Damara Sequence. A number of
different structural models have been proposed for the formation of these domes in the
literature. This study describes the structural geology of the Usakos dome. The study
discusses the structural evolution of the dome within the regional framework of the cSZ
that represents the high-grade metamorphic axis of the Damara Belt, characterized by
voluminous Pan-African granitoids.
The northeastern part of the Usakos dome is developed as an upright- to northwestverging
anticlinorium containing a steep southeasterly-dipping axial planar foliation. The
northeast fold trend persists into the southwestern parts of the Usakos dome. However,
this southwestern core of the dome is inundated by synkinematic granitic sheets. Distinct
marker horizons of the Damara Sequence outcrop as screens within the granite,
preserving a ghost stratigraphy. These screens illustrate the position and orientation of
second-order folds. Significantly, most of the stratigraphy of the Damara Sequence is
overturned in these folds. For example, some second-order anticlines developed in the
northeastern parts of the Usakos dome can be followed along their axial traces into the
southwestern hinge of the dome, where they appear as synformal anticlines, i.e.
synformal structures cored by older strata, plunging towards the northeast. The inverted
stratigraphy and northeasterly fold plunges suggest the northeast-trending folds are
refolded by second-generation, northwest-trending folds, thus, forming kilometer-scale
Type-2 interference folds. The resulting fold geometries are strongly non-cylindrical,
approaching southwest-closing sheath folds indicating a top-to-the-southwest material
transport. Lower-order folds in this overturned domain show radial fold plunges,
plunging away from the centre of the dome core, as well as a shallowly-dipping
schistosity. The close spatial and temporal relationship between granite intrusion and the formation
of the southwest-vergent, sheath-type folds, radial distribution of fold plunges and the
subhorizontal foliation confined to the southwestern hinge of the Usakos dome are
interpreted to signify the rheological weakening and ensuing collapse of the developing
first-order Usakos dome immediately above the synkinematic granite intrusions. Orogenparallel,
southwest-vergent sheath folds and top-to-the southwest extrusion of the
southwestern parts of the Usakos dome and northwest-vergent folding and thrusting
characterizing the northeastern extent of the Usakos dome are both responses to the
northwest-southeast- directed contractional tectonics recorded during the main collisional
phase in the Damara belt. On a regional scale, the Usakos dome represents the link
between the foreland-vergent northeastern part of the sCZ and the southwest-vergent,
high-grade southwestern parts of the sCZ.
The results of this study illustrate how dramatic variations in structural styles may be
caused by the localized and transient rheological weakening of the crust during plutonic
activity. / AFRIKAANSE OPSOMMING: Die noordoos-strekkende, suidelike Sentrale Sone (sSS) van die Pan-Afrikaanse Damara
gordel in sentraal Namibië word karakteriseer deur kilometer-skaal, noordoosstrekkende
koepel strukture, ontwikkel in die Neoproterozoïkum gesteentes van die
Damara Opeenvolging. 'n Aantal verskillende struktuur modelle is voorgestel in die
literatuur vir die vorming van hierdie koepels. Hierdie ondersoek beskryf die struktuur
geologie van die Usakos koepel. Die ondersoek bespreek die strukturele ontwikkeling van
die koepel in die regionale konteks van die sSS, wat die hoë graadse metamorfe
magmatiese as van die Damara Gordel verteenwoordig, en karakteriseer word deur
omvangryke Pan-Afrikaanse granitoïede.
Die noordoostelike gedeelte van die Usakos koepel is ontwikkel as 'n antiklinorium met
'n vertikale- tot noordwestelike kantelrigting. wat 'n steil hellende, suidoostelike asvlak
planêre foliasie bevat. Die noordoos-strekkende plooiing kom voor tot in die
suidwestelike kern van die Usakos wat ingedring is deur sinkinematiese granitiese plate.
Die posisie en oriëntasie van tweede-orde plooie is afgebeeld in die graniete deur 'n
skimstratigrafie wat preserveer is deur duidelike merker horisonne van die Damara
Opeenvolging. Die stratigrafie van die Damara Opeenvolging is opmerklik meestal
omgekeer in hierdie plooie. Byvoorbeeld, tweede-orde antikliene ontwikkel in die
noordoostelike gedeelte van die Usakos koepel kan gevolg word langs hul asvlakspore tot
in die suidwestelike skarnier van die koepel, waar dit voorkom as sinforme antikliene,
d.w.s. sinforme strukture met ouer strata in die kern wat na die noordooste duik. Die
omgekeerde stratigrafie en noordoostelike plooi duiking impliseer dat die noordoosstrekkende
plooie weer geplooi is deur tweede-generasie, noordwes-strekkende plooie,
wat dus aanleiding gegee het tot die vorming van kilometer-skaal, tipe-2 interferensie
plooie. Die gevolglike plooi geometrieë is uitdruklik nie-silindries, en toon 'n oorgang na
skede plooie met 'n sluiting na die suidweste, wat dui op 'n bokant-na-die-suidweste
materiaal vervoer. Laer-orde plooie in die omgekeerde domein vertoon radiale duiking
van die plooie, weg van die middelpunt van die koepel kern, sowel as 'n vlak hellende
skistositeit. Die noue ruimtelike en temporele verwantskap tussen graniet intrusie en die vorming van
skede-tipe plooie met 'n kantelrigting na die suidweste, die radiale verspreiding van
plooi duiking, en die subhorisontale foliasie wat beperk is tot die suidwestelike skarnier
van die Usakos koepel, word interpreteer as 'n aanduiding van die reologiese
verswakking en die gevolglike ineenstorting van die ontwikkelende eerste-orde Usakos
koepel, onmiddellik aan die bokant van die sinkinematiese graniet intrusies. Die orogeenparalleie
skede plooie met kantelrigting na die suidweste en bokant-na-die-suidweste
ekstrusie van die suidwestelike gedeelte van die Usakos koepel, en plooiing met
kantelrigting na die noordweste en stootverskuiwing wat kenmerkend is van die
noordoostelike gedeelte van die Usakos koepel, is beide 'n reaksie op die noordwessuidoos-
gerigte vernouings tektoniek opgeteken gedurende die hoof botsings fase in die
Damara gordel. Op 'n regionale skaal verteenwoordig die Usakos koepel die verbinding
tussen die noordoostelike gedeelte van die sSS met 'n voorland kantelrigting. en die hoë
graad suidwestelike gedeelte van die sSS met 'n kantelrigting na die suidweste.
Die resultate van hierdie ondersoek toon aan hoe dramatiese variasies in struktuur style
veroorsaak kan word deur die gelokaliseerde en kortstondige reologiese verswakking van
die kors gedurende plutoniese aktiwiteit.
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Conception d'un dôme géodésique pour des réservoirs à lisierDupéré, Richard January 1994 (has links)
A roof over a manure reservoir eliminates the entry of precipitations, reduces odour and volatile gas emissions, lowers the storage and handling costs and alleviates environmental impacts. / Structural analysis and testing were carried out to establish the feasibility of geodesic domes as manure reservoir roofting. A stress analysis, conducted by computer was used to determine maximum compression loads on roof members. Compression tests were carried out in the laboratory to test two laminated designs and to evaluate the performance of a member joint. / Structural analysis showed that the Lamella type dome, with a diameter/height ratio of 4, offers the best geometry considering design criteria for manure roofs. Compression tests confirmed that laminated members, made of 38 x 89 mm and 38 x 140 mm pieces, can resist the design stress developed in a 22 meter diameter dome. / Loading tests revealed that non laminated wood members failed at 80% of the design load. However, the joints (formed by two 3,1 mm thick steel plates bolted to the members) were still able to resist an increase in loading. / Data obtained from the tests were used for a preliminary design of a geodesic roof taking into account specific conditions such as humidity and manure gas. However further study is required to adapt this concept to real conditions over a manure reservoir. / The cost of a 22 meter diameter dome, for covering manure reservoirs, is estimated at 79$/m$ sp2$ which is more expensive than the cost of the currently used, least expensive manure pit roof (wood truss design).
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Wind flow over inflated spherical domesGanguli, Udeepta. January 1982 (has links)
No description available.
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Geology, geochemistry and petrology of the Pizarro and Pinto domes and the Tepeyahualco flows to the Los Humeros caldera complex, Puebla, MexicoGarcía-Banda, Rosalba January 1984 (has links)
No description available.
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