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


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


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


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


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







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


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)


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)


1 ft. snow adds 5413 lb to overall weight1 ft. snow adds 5413 lb to overall weightLLAJ AJ = 6168 lb (tension)= 6168 lb (tension)



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


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

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ENGR 20 Statics Raymond Great Hall Ceiling Trusses Stephen Morse Steven Granados