I. Design Standard and Parameters

For the design criteria and standards of the structural timber design, the designers refer to the

National Structural Code of the Philippines (NSCP 2010) Chapter 6 Wood works. The

methodology used as recommended by the code is Allowable Stress Design (ASD). Here are

the some of the data from the NSCP 2010 used in considering the design standards and

parameters.

Wind Directional Factor (Section 207.5.4.4, NSCP 2010 c 2)

Exposure Surface Roughness Category (Section 207.5.6.2, NSCP 2010 c 2)

Exposure (Section 207.5.6, NSCP 2010 c 2)

Velocity Pressure Exposure Coefficient (Section 207.5.6.6, NCSP 2010 c 2)

Terrain Exposure Constant, Table 207-5 (NSCP 2010 c 6)

Consensus Standards and Other Referenced Documents (Section 207.9, NSCP 2010 c 6)

Internal Pressure Coefficient

Roof Pressure Coefficient

Occupancy Categories (Section 208.4.2, NSCP 2010 c 2)

II. Design Process

Note: design ng rafter di ko na sinama kasi wala nman ako nun haha sareh :3

Design of Purlins:

1) Compute all the necessary loads that the purlins will carry.

Wind Load = (Pn)(Spacing of Purlins)(Length of Purlins)

Live Load = (Roof Live Load)(Tributary Area of Purlins)

Dead Load = RD [ ρwood

ρwater]

Roof Dead Load = (Roof Dead Load)(Length of Purlins)

Purlins Dead Load = (Unit Weight of Wood)(Cross-setional Area)(Spacing of Truss)

Total Dead Load = Roof Dead Loaf + Purlins Dead Load

2) Check For Bending

FbN(act .)=6 M

b d2

FbN(act .)<Fb (allow) (ok)

If not ok, increase the dimension of Purlins

3) Check for Slenderness Factor

C s<10 ; F ' b=Fb (Assumption is correct)

If not ok,F ' b≠ Fb, increase the dimension of Purlins

4) Check For Shearing

FV (act .)=3V2bd

FV (act .)<FV (allow) (ok)

If not ok, increase the dimension of Purlins

5) Check For Deflection

δ ALLOW= L240

δ ACTUAL=5W L2

384 EIδ ACTUAL<δALLOW=¿(ok)

If not ok, increase the dimension of Purlins

Load Combination:

1) Compute for Windward and Leeward- Bending Stress- Shear Stress- Deflection

Using the mentioned processes

Analysis of Truss:

1) Design SpecificationDead Loads (NSCP 2010 c 2)

2) Transfer the governing load to the truss and solve each fore member

3) Identify the wood specie and its visually stress grades (Table 6.1, NSCP 2010 c 6)

f c=PA

4) Assume base and depthFcACTUAL<FcALLOW=¿(ok)

If not ok, adjust assumed dimensions

Design of Flooring:1) Identify the wood specie and its visually stress grades (Table 6.1, NSCP 2010 c 6)

- Type of Flooring- Spacing of Joist

2) Assume base size of flooring

3) Test the allowable stresses

Design of Floor Joist:

1) Identify the wood specie and its visually stress grades (Table 6.1, NSCP 2010 c 2)- Bending and Tension Parallel to Grain- Shear Parallel to Grain- Modulus of Elasticity Bending- Allowable Compressive Stress Parallel to Grain- Length of Floor Joist- Wood Density (Table 6.2, NSCP2010 c 6)

2) Assume base size of floor joist(Test for the allowable stresses)

3) Determine total weight carried by the floor joist (flooring, DD, LL, Other Loads)

4) Test for allowable stresses

Design of Beams:

1) Identify the wood specie and its visually stress grades (Table 6.1, NSCP 2010 c 2)- Bending and Tension Parallel to Grain- Shear Parallel to Grain- Modulus of Elasticity Bending- Allowable Compressive Stress Parallel to Grain- Wood Density (Table 6.2, NSCP2010 c 6)- Effective Length or Buckling(Refer to Section 617.3)

2) Check for slenderness factor

C s=√ Led

b2 (Refer to Section 615.3.6)

3) Determine the weight of floor joist (from density of wood)

4) Determine the total weight

5) Test for allowable stresses

Design of Column:

1) Identify the wood specie and its visually stress grades (Table 6.1, NSCP 2010 c 2)- Bending and Tension Parallel to Grain- Shear Parallel to Grain- Modulus of Elasticity Bending- Allowable Compressive Stress Parallel to Grain- Wood Density (Table 6.2, NSCP2010 c 6)- Effective Length or Buckling(Refer to Section 617.3)

2) Get the dimension of truss

3) Test for type of column

4) Assume size of column

5) Test for allowable stresses