designe project

User Generated

Zbenq

Engineering

Description

I upload all the requirement

Unformatted Attachment Preview

Widener University Department of Civil Engineering CE 342 – Truss Design Project Objective: The Fun City Picnic Park has put out an RFP (Request for Proposals) on the design of a large open air pavilion. Your portion of the project is to design the wooden trusswork to support the roof, including layout of the truss geometry and selection of individual member sizes. You have to analyze and compare alternate designs by varying the truss geometry before selecting a final design. Geometry: Building dimensions are 30 ft by 100 ft, with the roof trusses to span the 30 ft dimension. Bays are spaced 25 ft apart, so the building will have 4 bays requiring a total of 5 identical roof trusses. Roof pitch (rise: run) is to be a minimum of 1:5 (3 ft high) and a maximum of 1:2 (7.5 ft high). To adequately support the selected roofing, roof purlins will be spaced no more than 8 feet apart. See sketch below. Individual member lengths are restricted to no more than 10 feet. Alternate your design by either (1) changing the roof pitch; or by (2) changing the purlin spacing. The direction of your diagonal members should be reversed in each of the alternate designs for a total of 3 truss geometries to be analyzed. Roofing material 3 ft min. 7.5 ft max. 8 ft max. 25 ft 30 ft Loads: Dead load (DL): Weight of roofing and supporting purlins is estimated to be 6 psf. Snow load (SL): Ground snow load = 30 psf for the Fun City area. You can conservatively calculate the snow load on the horizontal projection of the roof using the equations given in Section 2.5 of your textbook. Assume the pavilion is located in a sheltered area and that the roof slope coefficient Cs =1. Wind load (WL): Uplift (tension) perpendicular to roof = 22 psf on windward side and 12 psf on leeward side of roof (wind may come from either side of roof). Load Combinations and Load Duration Factors: For each load combination provided below, the NDS design specification provides a load duration factor that is applied to the base design stress value of the lumber. To simply your calculations, you can divide the loads calculated for each load combination by the load duration factor shown. DL Only DL + SL DL + WL DL + WL + 0.5 SL CD = 0.9 (long term loading CD = 1.15 (2 month load duration) CD = 1.6 (10 minute load duration) CD = 1.6 (10 minute load duration) Materials: Trusses will be fabricated from sawn lumber (see table for nominal sizes and section properties) Select Structural Douglas Fir-South (see Table 1 for base values of allowable strengths and modulus of elasticity E, assume density = 30 pcf). Keep in mind that although it is possible to have different sizes for every member, it will be less confusing during fabrication if you limit the number of different sizes in your design; thus use no more than 4 different nominal sizes. Maximum member length is 10 feet. Allowable Stresses: Compression members will be fabricated with compressive stress parallel to the wood grain (use Fc as base value for allowable stress in compression). Members in tension MUST be fabricated with tension stress parallel to the grain (use Ft as base value for allowable stress in tension). As the pavilion is open-air, the moisture content of the wood may exceed 19% in use, which requires a wet-use adjustment factor Cm = 0.9 applied to the base value for modulus of elasticity (multiply base value for E from the table by Cm = 0.9) and Cm = 0.8 applied to the base value for allowable compression stress (multiply Fc base value from the table by Cm = 0.8). Allowable tension stress has a wet-use adjustment factor Cm = 1. In addition to the wet-use adjustment factor, the base values for tension and compression stresses must also be multiplied by appropriate modification factors for member size CF. Values of CF vary depending on member size and whether the member is in tension or compression. See Table A for values of CF. Buckling of Compression Members: Compression members must also be checked for the possibility of member buckling. The allowable buckling stress Fcr, which is based on the Euler buckling equation, is calculated from Fcr = 0.3E/(l/d)2 where Fcr = allowable buckling stress for compression members, E = modulus of elasticity (remember to adjust by the 0.9 wet-use factor) l = unsupported member length d = critical (smaller) net cross sectional dimension. In addition, no compression member is permitted to have an l/d ratio larger than 50. Design Tools: RISA 2D structural analysis software will be helpful in analyzing your designs under the various load combinations. The RISA 2D software can be downloaded from the textbook website at www.mhhe.com/leet. Note that this version of the RISA software limits you to a maximum of 50 members and 50 joints. Deliverables: Provide a report that includes the following items. 1. Fully dimensioned CAD drawing of your 3 alternate truss designs, with purlin locations indicated. 2. Load calculations, include figures showing all load cases you consider in your analysis. 3. Results of structural analysis for each load case. Printout from your RISA analysis, including data and results. 4. A table comparing your alternate designs that shows, for each member, the member length and maximum member force in tension and compression. 5. A discussion of the pros and cons of each design, and your recommendation for which design should be selected to be built. Keep in mind that cost will depend on a number of factors including total truss weight, selected member sizes (deeper or thicker members can be harder to come by than narrower or thinner members so a 2 x 8 or a 4 x 4 may be more than twice as expensive as a 2 x 4), and number of joints (the labor that goes into framing the joints is time intensive so minimizing the number of connections is a good idea, provided that doesn’t lead to unrealistically large member sizes). 6. A table for your final design that shows, for each member, member length, maximum member force in tension, maximum member force in compression, and chosen member size. Deadline: In class Tuesday November 14th, 2017 Framing Lumber ADJUSTMENT FACTORS FOR BASE VALUES DURATION OF LOAD ADJUSTMENT (CD ) Table C Apply to size-adjusted values Wood has the property of carrying substantially greater maximum loads for short durations than for long durations of loading. Tabulated design values apply to normal load duration. (Factors do not apply to MOE or Fc⊥) Table A SIZE FACTORS (CF) Apply to Dimension lumber BASE VALUES Load Duration Fb Nominal Width (depth) Grades 2 & 3 4 thick thick nominal nominal Ft Fc Other Properties 2″, 3″, & 4″ 5″ 6″ 8″ 10″ 12″ 14″ & wider 1.5 1.4 1.3 1.2 1.1 1.0 0.9 1.5 1.4 1.3 1.3 1.2 1.1 1.0 1.5 1.4 1.3 1.2 1.1 1.0 0.9 1.15 1.1 1.1 1.05 1.0 1.0 0.9 1.0 1.0 1.0 1.0 1.0 1.0 1.0 CONSTRUCTION 2″, 3″, & 4″ & STANDARD 1.0 1.0 1.0 1.0 1.0 2″ & 3″ 4″ 0.4 1.0 — 1.0 0.4 1.0 0.6 1.0 1.0 1.0 2″, 3″, & 4″ 5″ & 6″ 1.1 1.0 1.1 1.0 1.1 1.0 1.05 1.0 1.0 1.0 8″ & wider Use No.3 grade Base Values and Size Factors SELECT STRUCTURAL, NO.1 & BTR., NO.1, NO.2 & NO.3 UTILITY STUD 1 UBC recognizes a factor of 1.33 for ten minute load duration. HORIZONTAL SHEAR DESIGN VALUES Horizontal shear values published in Tables 1, 3, 4 and 5 are based upon the maximum degree of shake, check or split that might develop in a piece. Shear design values for lumber have recently been revised and approved by the American Lumber Standard Committee, Inc., in accordance with changes in ASTM D245, Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber. These new lumber shear values are higher than earlier assigned values and no longer subject to the horizontal shear adjustment factor CH. Design provisions, including requirements for shear design of lumber, are published by the American Forest & Paper Association (AF&PA) in the National Design Specification ® for Wood Construction (NDS), an ANSI national consensus standard. The new shear values can be used in conjunction with 1997 NDS, except for shear design at notches and connections. Under these exceptions only design values listed in the 1997 NDS Supplement: Design Values for Wood Construction, or similar values apply. Shear provisions for tension-side notches, and shear design for bending members at connections, have been revised in the 2001 NDS in order to fully utilize the new lumber shear values. For further information on the new shear design value provisions, contact the American Wood Council Help Desk at 202-463-4713 or by e-mail at awcinfo@afandpa.org. Apply to size-adjusted Fb Where lumber is used repetitively, such as for joists, studs, rafters, and decking, the pieces side by side share the load and the strength of the entire assembly is enhanced. Therefore, where three or more members are adjacent or are not more than 24″ on center and are joined by floor, roof, or other load distributing elements, the Fb value can be increased 1.15 for repetitive member use. 0.9 1.0 1.15 1.25 1.61 2.0 Confirm load requirements with local codes. Table B REPETITIVE MEMBER FACTOR (Cr ) Factor Permanent Ten Years (Normal Load) Two Months (Snow Load) Seven Day Ten Minutes (Wind and Earthquake Loads) Impact Repetitive Member Use Fb  1.15 Checklist 1 ADJUSTMENTS FOR DIMENSION LUMBER The boxes in the checklist below indicate when and how to apply adjustments (Tables A–G) to the BASE VALUES in Table 1. Base Values Base Value Fb Ft Fv Fc ⊥ Fc E Table 1 page 6 x Adjustment Factors x Repetitive Member Cr Size CF □ □ x □ Special Use Factors x x Duration of Load CD □ □ □ x Flat Use Cfu x Compression Perpendicular Cc⊥ □ □ □ Table A □ Table B page 7 Table C Table D x Incising, Wet Use, Fire-Retardant 1, High-Temperature Ci CM CR C t □ □ □ □ □ □ = Design Values = Design Value F ′b F ′t F ′v F c′ ⊥ F ′c E′ Bending Tension Shear Compression Perpendicular Compression Parallel Stiffness Table E Tables F&G, Ch. 2 of NDS page 9 and the National Design Specification (NDS) 1 Adjustments for fire-retardant treatment shall be provided by the manufacturer providing the treatment. 7 Framing Lumber PROPERTIES OF STANDARD DRESSED SIZES (S4S) SECTION PROPERTIES OF JOISTS AND BEAMS Certain mathematical expressions of the properties or elements of sections are used in computing the values of structural members of various shapes for the various conditions under which they are subjected to stress. The properties or elements of sections of standard sizes of joists, planks, beams, stringers, posts, timbers and decking are given in the following tables. NEUTRAL AXIS, X–X in the diagrams, in the cross section of a beam or column in a state of flexure, is the line on which there is neither tension nor compression. In the following tables, which show the properties of the rectangular and square sections of lumber, the neutral axis has been assumed as perpendicular to the depth of the section at its center, the depth ‘‘h’’ being parallel to and in the direction of the application of the force or load. MOMENT OF INERTIA, I, of the cross section of a beam is the sum of the products of each of its elementary areas by the square of their distance from the neutral axis of the section. SECTION MODULUS, S, is the moment of inertia divided by the distance from the neutral axis to the extreme fiber of the section. CROSS SECTION is a section taken through the member perpendicular to its longitudinal axis. SECTION PROPERTIES OF PLANKS Nominal Size in Inches bh x Section Modulus (S ) Surfaced Size for Design in Inches bh Area (A) A = bh (in2) S = bh 2 6 (in3) h Moment of Board Inertia (I ) Feet per Lineal bh 3 I = Foot of 12 Piece (in4) 3 4 6 8 10 12 × × × × × × 2 2 2 2 2 2 2.5 3.5 5.5 7.25 9.25 11.25 × × × × × × 1.5 1.5 1.5 1.5 1.5 1.5 3.75 5.25 8.25 10.88 13.88 16.88 0.938 1.312 2.062 2.719 3.469 4.219 0.703 0.984 1.547 2.039 2.602 3.164 0.50 0.67 1.00 1.33 1.67 2.00 4 6 8 10 12 14 16 × × × × × × × 3 3 3 3 3 3 3 3.5 5.5 7.25 9.25 11.25 13.25 15.25 × × × × × × × 2.5 2.5 2.5 2.5 2.5 2.5 2.5 8.75 13.75 18.12 23.12 28.12 33.12 38.12 3.646 5.729 7.552 9.635 11.719 13.802 15.885 4.557 7.161 9.440 12.044 14.648 17.253 19.857 1.00 1.50 2.00 2.50 3.00 3.50 4.00 6 8 10 12 14 16 × × × × × × 4 4 4 4 4 4 5.5 7.25 9.25 11.25 13.25 15.25 × × × × × × 3.5 3.5 3.5 3.5 3.5 3.5 19.25 25.38 32.38 39.38 46.38 53.38 11.229 14.802 18.885 22.969 27.052 31.135 19.651 25.904 33.049 40.195 47.341 54.487 2.00 2.67 3.33 4.00 4.67 5.33 SECTION PROPERTIES OF DECKING (per foot of width) Surfaced Nominal Size Size for Design in Inches in Inches h bh 2 3 4 16 Table 11 b x 12 × 1.5 2.5 3.5 x Section Modulus (S) Area (A) A = bh (in2) 18.00 30.00 42.00 Table 12 12'' x h Moment of Inertia (I ) (in3) (in4) Board Feet per Lineal Foot of Piece 4.50 12.50 24.50 3.375 15.625 42.875 2.00 3.00 4.00 S = bh 2 6 I = bh 3 12 x Nominal Size in Inches bh Surfaced Size for Design in Inches bh Table 13 b x h Section Moment of Board Modulus (S) Inertia (I ) Feet per Area (A) Lineal bh 3 bh 2 I = S = A = bh Foot of 12 6 (in2) (in3) (in4) Piece 2 2 2 2 2 2 2 2 × 2 × 3 × 4 × 6 × 8 × 10 × 12 × 14 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 × × × × × × × × 1.5 2.5 3.5 5.5 7.25 9.25 11.25 13.25 2.25 3.75 5.25 8.25 10.88 13.88 16.88 19.88 0.562 1.56 3.06 7.56 13.14 21.39 31.64 43.89 0.422 1.95 5.36 20.80 47.63 98.93 177.98 290.78 0.33 0.50 0.67 1.00 1.33 1.67 2.00 2.33 3 3 3 3 3 3 3 3 × 3 × 4 × 6 × 8 × 10 × 12 × 14 × 16 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 × × × × × × × × 2.5 3.5 5.5 7.25 9.25 11.25 13.25 15.25 6.25 8.75 13.75 18.12 23.12 28.12 33.12 38.12 2.60 5.10 12.60 21.90 35.65 52.73 73.15 96.90 3.26 8.93 34.66 79.39 164.89 296.63 484.63 738.87 0.75 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4 4 4 4 4 4 4 × 4 × 6 × 8 × 10 × 12 × 14 × 16 3.5 3.5 3.5 3.5 3.5 3.5 3.5 × × × × × × × 3.5 5.5 7.25 9.25 11.25 13.25 15.25 12.25 19.25 25.38 32.38 39.38 46.38 53.38 7.15 17.65 30.66 49.91 73.83 102.41 135.66 12.51 48.53 111.15 230.84 415.28 678.48 1034.42 1.33 2.00 2.67 3.33 4.00 4.67 5.33 6 6 6 6 6 6 6 6 × 6 × 8 × 10 × 12 × 14 × 16 × 18 × 20 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 × × × × × × × × 5.5 7.5 9.5 11.5 13.5 15.5 17.5 19.5 30.25 41.25 52.25 63.25 74.25 85.25 96.25 107.25 27.73 51.56 82.73 121.23 167.06 220.23 280.73 348.56 76.26 193.36 392.96 697.07 1127.67 1706.78 2456.38 3398.48 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 8 8 8 8 8 8 8 8 8 × 8 × 10 × 12 × 14 × 16 × 18 × 20 × 22 × 24 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 × × × × × × × × × 7.5 9.5 11.5 13.5 15.5 17.5 19.5 21.5 23.5 56.25 71.25 86.25 101.25 116.25 131.25 146.25 161.25 176.25 70.31 112.81 165.31 227.81 300.31 382.81 475.31 577.81 690.31 263.67 535.86 950.55 1537.73 2327.42 3349.61 4634.30 6211.48 8111.17 5.33 6.67 8.00 9.33 10.67 12.00 13.33 14.67 16.00 10 10 10 10 10 10 10 × 10 × 12 × 14 × 16 × 18 × 20 × 22 9.5 9.5 9.5 9.5 9.5 9.5 9.5 × × × × × × × 9.5 11.5 13.5 15.5 17.5 19.5 21.5 90.25 109.25 128.25 147.25 166.25 185.25 204.25 142.90 209.40 288.56 380.40 484.90 602.06 731.90 678.76 1204.03 1947.80 2948.07 4242.84 5870.11 7867.88 8.33 10.00 11.67 13.33 15.00 16.67 18.33 12 12 12 12 12 12 12 × 12 × 14 × 16 × 18 × 20 × 22 × 24 11.5 11.5 11.5 11.5 11.5 11.5 11.5 × × × × × × × 11.5 13.5 15.5 17.5 19.5 21.5 23.5 132.25 155.25 178.25 201.25 224.25 247.25 270.25 253.48 349.31 460.48 586.98 728.81 885.98 1058.48 1457.51 2357.86 3568.71 5136.07 7105.92 9524.28 12437.13 12.00 14.00 16.00 18.00 20.00 22.00 24.00 Member nominal size 2x2 2x3 2x4 2x6 2x8 2x10 2x12 2x14 3x3 3x4 3x6 3x8 3x10 3x12 3x14 4x4 4x6 4x8 4x10 4x12 4x14 Cross Allowable Actual section Member size area in2 Tension lbs 1.5x1.5 2.25 3122 1.5x2.5 3.75 5203 1.5x3.5 5.25 7284 1.5x5.5 8.25 11447 1.5x7.5 11.25 15609 1.5x9.25 13.875 19252 1.5x11.25 16.875 23414 1.5x13.25 19.875 27577 2.5x2.5 6.25 8672 2.5x3.5 8.75 12141 2.5x5.5 13.75 19078 2.5x7.5 18.75 26016 2.5x9.25 23.125 32086 2.5x11.25 28.125 39023 2.5x13.25 33.125 45961 3.5x3.5 12.25 16997 3.5x5.5 19.25 26709 3.5x7.5 26.25 36422 3.5x9.25 32.375 44920 3.5x11.25 39.375 54633 3.5x13.25 46.375 64345 Allowable Member Compression lbs 3105 5175 7245 11385 15525 19147.5 23287.5 27427.5 8625 12075 18975 25875 31912.5 38812.5 45712.5 16905 26565 36225 44677.5 54337.5 63997.5 Allowable Buckling Load for 10 ft Member, lbs E 152 253 354 557 759 937 1139 1342 1172 1641 2578 3516 4336 5273 6211 4502 7074 9647 11898 14470 17043 1440000 * Remember to compute for the exterior truss & for the interior truss The exteriors are the 2 to the ends of the air pavilion ** Modify the length for the buckling load psi e interior truss
Purchase answer to see full attachment
User generated content is uploaded by users for the purposes of learning and should be used following Studypool's honor code & terms of service.

Explanation & Answer

I want you to send it to my email.. but I am worried that the admin will bond us here. just send those file through and the admin will forward to me..
Attached.

Widener University
Department of Civil Engineering
CE 342 – Truss Design Project

Fully dimensioned CAD drawing

Load calculations and Results of structural analysis for each load case

ΣMD=0ΣMD=0
2xRA=450x2xRA=450x
RA=225NRA=225N

ΣMA=0ΣMA=0
2xVD=450x+(450sin30∘)(2x)2xVD=450x+(450sin⁡30∘)(2x)
VD=450NVD=450N
ΣFH=0ΣFH=0
HD=450cos30∘=389.71NHD=450cos⁡30∘=389.71N
At Joint A
ΣFV=0ΣFV=0

FABsin30∘=225FABsin⁡30∘=225
FAB=450NFAB=450N
ΣFH=0ΣFH=0

FAC=FABcos30∘=450cos30∘FAC=FABcos⁡30∘=450cos⁡30∘
FAC=389.71NFAC=389.71N

At Joint C
ΣFV=0ΣFV=0

FBC=450NFBC=450N
ΣFH=0ΣFH=0
FCD=389.71NFCD=389.71N
At Joint B
ΣFH=0ΣFH=0

FBDcos30∘=45...


Anonymous
Just the thing I needed, saved me a lot of time.

Studypool
4.7
Trustpilot
4.5
Sitejabber
4.4

Related Tags