Introduction to Structural Member Properties

Structural Member Properties Moment of Inertia (I) In general, a higher moment of inertia produces a greater resistance to deformation. Stiffness of an object related to its shape ©iStockphoto.com

BeamMaterialLengthWidthHeightArea ADouglas Fir8 ft1 ½ in.5 ½ in.8 ¼ in. 2 BDouglas Fir8 ft5 ½ in.1 ½ in.8 ¼ in. 2 Moment of Inertia Principles Joist Plank

Calculating Moment of Inertia – Rectangles Moment of Inertia Principles h

Modulus of Elasticity (E) This defines the stiffness of an object related to material chemical properties. In general, a higher modulus of elasticity produces a greater resistance to deformation. Structural Member Properties Chemical Makeup

Modulus of Elasticity Principles BeamMaterialLengthWidthHeightAreaI ADouglas Fir8 ft1 ½ in.5 ½ in.8 ¼ in in. 4 BABS plastic8 ft1 ½ in.5 ½ in.8 ¼ in in. 4

Modulus of Elasticity Principles Applied force or load Length of span between supports Modulus of elasticity Moment of inertia Characteristics of objects that affect deflection (Δ MAX )

Force Vectors The next few slides deal with Force Vectors This is to calculate how a force and its angle affect resultant magnitude

Sense +x (right) -x (left) +y (up) -y (down) (0,0)

Trigonometry Review Hypotenuse (hyp) 90° Opposite Side (opp) Adjacent Side (adj) Right Triangle A triangle with a 90° angle Sum of all interior angles = 180° Pythagorean Theorem: c 2 = a 2 + b 2

Trigonometry Review sin θ° = opp / hyp cos θ° = adj / hyp tan θ° = opp / adj Trigonometric Functions soh cah toa

Resultant Force Two people are pulling a boat to shore. They are pulling with the same magnitude.