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PDG: Post Design Graph Copyright Prof Schierle 2012 1 PDG: Post Design Graph - tutorial PDG is an Excel program to design and visualize posts in wood,

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Presentation on theme: "PDG: Post Design Graph Copyright Prof Schierle 2012 1 PDG: Post Design Graph - tutorial PDG is an Excel program to design and visualize posts in wood,"— Presentation transcript:

1 PDG: Post Design Graph Copyright Prof Schierle 2012 1 PDG: Post Design Graph - tutorial PDG is an Excel program to design and visualize posts in wood, steel, concrete, and masonry PDG requires some knowledge of post design PDG requires a PC with MS Excel macros Enabled Press > for next step, < for previous step Press Esc to end PDG wood steel concrete masonry

2 PDG: Post Design Graph Copyright Prof Schierle 2012 2 PDG: Post Design Graph - tutorial Stress output C = concrete M = masonry S = steel W = wood fb = bending stress fa = axial stress Input data info Visualization graph Bending (k)

3 PDG: Post Design Graph Copyright Prof Schierle 2012 3 PDG: Post Design Graph - tutorial Select post material (5 to clear screen) Prior to running PDG Enter design data or use pre-defined data Optionally, copy default data from TU to AB Press Ctr-Shift-R to run PDG

4 PDG: Post Design Graph Copyright Prof Schierle 2012 4 PDG: Post Design Graph - tutorial Wood buckling Allowable buckling stress F c F c = F * c (C P ) F * c = F c (C D ) (C M ) (C t ) X …… F c = Allowable compressive stress parallel to grain C D = Duration factor (1=normal, 1.6=wind & seismic load) C M = Moisture factor (1 for dry lumber) C t = Temperature factor (1for normal temperature) X = Other adjustment factors for size, etc. per NDS C P = Buckling stability defined by Ylinen formula: c = 0.80 for sawn lumber 0.85 for round timber 0.90 for glulam posts F cE = K cE E/(L/d) 2 (Euler buckling stress) K cE = 0.300 for visually graded lumber 0.384 for MEL (Machine Evaluated Lumber) 0.418 for glulam & MSR (Machine Stress Rated) E = Elastic modulus Wood buckling Allowable buckling graph Horizontal axis: slenderness L/d Vertical axis: allowable stress Fc Allowable buckling load: P = A Fc A = cross section area

5 PDG: Post Design Graph Copyright Prof Schierle 2012 5 PDG: Post Design Graph - tutorial Elastic buckling: Allowable buckling stress: Inelastic buckling: K-factors theoretical - defined by support types K-factors recommended at Steel buckling Based on empirical tests steel has 2 buckling modes: Inelastic buckling (KL/r < C c ) Elastic buckling (KL/r > C c ) C c at ~ Fy/2 is derived using Eulers formula: For F y = 50 ksi C c = 107 For F y = 36 ksi C c = 126 F.S. = factor of safety, computed as: 1.2 - 1.5 InelasticElastic

6 PDG: Post Design Graph Copyright Prof Schierle 2012 6 PDG: Post Design Graph - tutorial Concrete buckling Note: PDG uses approximate masonry slenderness reduction Fc = InputBox("Input concrete compressive strength (3-12 ksi)") Cpercent = InputBox("Input percent reinforcing (1-8%)") Fy = InputBox("Select steel rebar strength Fy (50 ksi, 60 ksi)") Fsc = 0.4 * Fy Cfx = Cpercent / 100 Cf = 0.7 * 0.8 * 0.85 * (1 - Cfx) + Fsc * (Cfx) If post = round Then Cf = 0.75*0.85*0.85*(1-Cfx)+Fsc*(Cfx) D = concreteYdepth If Cshape = 1 Then D = concreteXdepth r = Sqr(D ^ 2 / 12) If post = round Then D = concrete diameter: r = D / 2 Lrratio = (k * 12 * concretelength) / r Aconc = concreteXdepth * concreteYdepth If post = round Then Aconc = Pi*(concretediameter / 2)^2 For I = 1 To concretelength h = I * 12 HRratio = h / r Fa = Cf * Fc * (1 - (h / (140 * r)) ^ 2) If HRratio > 99 Then Fa = Cf * Fc * (70 * r / h) ^ 2 P = Fa * Aconc Next I Masonry buckling Mpercent = InputBox("Input percent reinforcing (0.5-4%)") Fy = InputBox("Select rebar strength Fy (50, 60 ksi)") Fsm = 0.4 * Fy D = masonryYdepth If Mbuckling = 1 Then D = masonryXdepth r = Sqr(D ^ 2 / 12) HRratio = (k * 12 * masonrylength) / r Agm = masonryXdepth * masonryYdepth Asm = Agm * Mpercent / 100 Anm = Agm - Asm Fmt = (0.25 * Fm * Anm + 0.65 * Asm * Fsm) / Agm For I = 1 To masonrylength h = I * 12 HRratio = h / r Fa = Fmt * (1 - (h / (140 * r)) ^ 2) If HRratio > 99 Then Fa = Fmt * (70 * r / h) ^ 2 P = Fa * Agm Next I

7 PDG: Post Design Graph Copyright Prof Schierle 2012 7 PDG: Post Design Graph - tutorial Copy any or all columns to paste into a new Excel sheet to make graphs, or make graphs on this Excel sheet

8 PDG: Post Design Graph Copyright Prof Schierle 2012 8 PDG: Post Design Graph - tutorial Paste (Ctrl V) selections to a new Excel sheet Select Insert mode

9 PDG: Post Design Graph Copyright Prof Schierle 2012 9 PDG: Post Design Graph - tutorial Select graph type Select a column To make graphs

10 PDG: Post Design Graph Copyright Prof Schierle 2012 10 PDG: Post Design Graph - tutorial Load graphs: wood steel concrete masonry X-axis Y-axis

11 PDG: Post Design Graph Copyright Prof Schierle 2012 11 PDG: Post Design Graph - tutorial Select number sequence for proper density Optionally move chart to separate sheet Optionally scale chart Format axis numbers without decimals

12 PDG: Post Design Graph Copyright Prof Schierle 2012 12 PDG: Post Design Graph - tutorial Optional color chart Length (feet) Capacity (kip)


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