ENGR 20 Statics Raymond Great Hall Ceiling Trusses Stephen Morse Steven Granados.
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Transcript of ENGR 20 Statics Raymond Great Hall Ceiling Trusses Stephen Morse Steven Granados.
ENGR 20 StaticsENGR 20 Statics
Raymond Great Hall Ceiling Raymond Great Hall Ceiling TrussesTrusses
Stephen Morse
Steven Granados
Table of ContentsTable of Contents
BackgroundBackground
HistoryHistory
Materials and MethodsMaterials and Methods
CalculationsCalculations
ConclusionConclusion
DiscussionDiscussion
ReferencesReferences
BackgroundBackground
PurposePurpose Discover the forces Discover the forces
present in the present in the members of the truss members of the truss under normal under normal conditionsconditions
Free body diagram of roof truss
Labeling convention
Determine the Determine the maximum tensile and maximum tensile and compressive forces in compressive forces in the truss membersthe truss members
Normal conditionsNormal conditions
Extreme conditionsExtreme conditions
BackgroundBackground
AssumptionsAssumptions Roof modeled two waysRoof modeled two ways
Uniformly distributed loadUniformly distributed load
Discrete forces acting at the jointsDiscrete forces acting at the joints One truss supports 15 linear ft. of roofOne truss supports 15 linear ft. of roof Weight of roof and hanging lights left as Weight of roof and hanging lights left as
variablesvariables Weights of beams in trusses were ignoredWeights of beams in trusses were ignored Length of beams were estimated from groundLength of beams were estimated from ground
HistoryHistoryBuilt in 1962Built in 1962
Dedicated on October 13, 1962Dedicated on October 13, 1962
Part of Raymond “Cluster” CollegePart of Raymond “Cluster” College
Built over Baxter StadiumBuilt over Baxter Stadium
Materials and MethodsMaterials and Methods
MaterialsMaterials WoodWood Wood sealantWood sealant Steel gusset platesSteel gusset plates Steel boltsSteel bolts
Construction StyleConstruction Style Modernistic English Modernistic English
Georgian ArchitectureGeorgian Architecture Unfinished wood Unfinished wood
beamsbeams
Materials and MethodsMaterials and Methods
Material SelectionMaterial Selection CostCost
Wood was cheaper than steelWood was cheaper than steel Aesthetic virtuesAesthetic virtues
CalculationsCalculationsAssumptions RestatedAssumptions Restated Roof modeled two waysRoof modeled two ways
Uniformly distributed loadUniformly distributed loadDiscrete forces acting at the jointsDiscrete forces acting at the joints
Weight of roof and hanging lights left as variablesWeight of roof and hanging lights left as variables Weights of beams in trusses were ignoredWeights of beams in trusses were ignored Length of beams were estimated from groundLength of beams were estimated from ground
Calculation MethodsCalculation Methods Method of JointsMethod of Joints Method of SectionsMethod of Sections
CalculationsCalculations
CalculationsCalculations
CalculationsCalculations
CalculationsCalculations
CalculationsCalculations
ConclusionConclusion
AB = -41.500R – 3.607LAB = -41.500R – 3.607L BC = -37.865R – 0.698LBC = -37.865R – 0.698L CD = -51.440R – 3.487LCD = -51.440R – 3.487L AJ = 27.033R + 3.113LAJ = 27.033R + 3.113L JI = 16.703R + 1.908LJI = 16.703R + 1.908L
CI = 24.090R + 1.908LCI = 24.090R + 1.908L BJ = -10.005R – 1.185LBJ = -10.005R – 1.185L JC = 7.948R + 1.942LJC = 7.948R + 1.942L DI = -6RDI = -6R
*Note: positive forces denote *Note: positive forces denote tension, negative denote tension, negative denote compressioncompression
Calculated Forces
ConclusionConclusion
There are no zero force membersThere are no zero force members
Under normal conditionsUnder normal conditions Member AJ bears the maximum load in Member AJ bears the maximum load in
tensiontensionLLAJ AJ = 3637 lb (tension)= 3637 lb (tension)
Member CD bears the maximum load in Member CD bears the maximum load in compressioncompression
LLCDCD = 6751 lb (compression) = 6751 lb (compression)
ConclusionConclusion
Maximum loads under special conditionsMaximum loads under special conditions ¼ in. rain adds 1128 lb to overall weight¼ in. rain adds 1128 lb to overall weight
LLAJ AJ = 4165 lb (tension)= 4165 lb (tension)
LLCDCD = 7754 lb (compression) = 7754 lb (compression)
1 ft. snow adds 5413 lb to overall weight1 ft. snow adds 5413 lb to overall weightLLAJ AJ = 6168 lb (tension)= 6168 lb (tension)
LLCDCD = 11566 lb (compression) = 11566 lb (compression)
DiscussionDiscussion
Pros and Cons of DesignPros and Cons of Design Adequate structural integrity to support roofAdequate structural integrity to support roof Aesthetically pleasingAesthetically pleasing Not as strong as steelNot as strong as steel Weight (solid beams are heavy)Weight (solid beams are heavy)
Anticipated Failure PointsAnticipated Failure Points These will be based on the material properties of These will be based on the material properties of
wood, which will be covered in materials sciencewood, which will be covered in materials science
Life ExpectancyLife Expectancy Sealed wood structures can last for hundreds of years Sealed wood structures can last for hundreds of years
under good conditionsunder good conditions
DiscussionDiscussion
Design ImprovementsDesign Improvements Addition of zero-force members for redundancyAddition of zero-force members for redundancy Use of steel “I-beams” instead of solid woodUse of steel “I-beams” instead of solid wood
ReferencesReferences
Professor Jeff BurmeisterProfessor Jeff BurmeisterDon Walker, UOP library archivist and historianDon Walker, UOP library archivist and historianUOP physical plantUOP physical plantPacific Weekly newspaper (library archives)Pacific Weekly newspaper (library archives)Photo file on Raymond College (library archives)Photo file on Raymond College (library archives)CSAC CSAC http://http://www.csac.org/Education/glossary/density.htmlwww.csac.org/Education/glossary/density.htmlPSC Roofing Tiles PSC Roofing Tiles http://http://www.pragatisales.com/roofing_tiles.htmwww.pragatisales.com/roofing_tiles.htm Bob Vila Home Improvement Website Bob Vila Home Improvement Website http://www.bobvila.com/HowTo/TipLibrary/Subjehttp://www.bobvila.com/HowTo/TipLibrary/Subject/Carpentry/Engineered_Wood/0389-Plywood_ct/Carpentry/Engineered_Wood/0389-Plywood_Weight.htmlWeight.html